E-Prime USER'S GUIDE Walter Schneider*, Amy Eschman and Anthony Zuccolotto Psychology Software Tools, Inc. *Learning Research and Development Center, University of Pittsburgh With assistance from: Sara Burgess, Brandon Cernicky, Debbie Gilkey, Jennifer Gliptis, Valerie Maciejczyk, Brian MacWhinney, Kimberly Rodgers, and James St. James Copyright 2002 Psychology Software Tools, Inc. All rights reserved.
Preface The goal of developing the E-Prime suite of applications is to provide a common, standardized, precise, computer research language for psychology that can be used on today's technologically advanced computers. The E-Prime suite is designed to allow rapid development of experiments that can be run with precision on computers around the world. A common computer language enables researchers in different universities to communicate and share experimental procedures and data.
E-Prime User’s Guide Table of Contents Table of Contents Chapter 1 : Introduction________________________________________________________________ 1 1.1 E-Prime_____________________________________________________________________ 1 1.2 Installation Instructions _______________________________________________________ 1 1.2.1 Machine Requirements for Intel PCs ___________________________________________ 1 1.2.2 Installing ________________________________________________________________ 1 1.
E-Prime User’s Guide Table of Contents 2.4 Stage 2: Elaborate the Trial Procedure _________________________________________ 2.4.1 Add Get Ready display ____________________________________________________ 2.4.2 Add instructions to Fixation and Probe displays_________________________________ 2.4.3 Add Prime______________________________________________________________ 2.4.4 Add Feedback ___________________________________________________________ 2.4.
E-Prime User’s Guide Table of Contents 3.2 Introduction to Timing Issues__________________________________________________ 72 3.2.1 Problem 1: Computer operating systems can falsely report timing data_______________ 75 3.2.2 Problem 2: Actual durations can deviate from intended durations ___________________ 76 3.2.3 Problem 3: Displays are accomplished via refresh cycles__________________________ 79 3.2.4 Problem 4: Accurately measuring and reporting timing, then debugging an experiment __ 83 3.
E-Prime User’s Guide Table of Contents 4.7.4 4.7.5 Examples _____________________________________________________________ 160 Additional Information ___________________________________________________ 162 4.8 Debugging in E-Prime ______________________________________________________ 162 4.8.1 Tips to help make debugging easier _________________________________________ 164 Chapter 5 : Data Handling ___________________________________________________________ 165 5.
E-Prime User’s Guide Table of Contents The Single-Trial, Reaction-Time Paradigm __________________________________________ A-25 General Considerations___________________________________________________________ A-26 An example experiment __________________________________________________________ A-26 What happens on each trial? ______________________________________________________ A-26 What happens within a block of trials? ______________________________________________ A-28 Blocked versus random presentat
E-Prime User’s Guide Chapter 1: Introduction Chapter 1: Introduction 1.1 E-Prime E-Prime is a comprehensive suite of applications offering audited millisecond-timing precision, enabling researchers to develop a wide variety of paradigms that can be implemented with randomized or fixed presentation of text, pictures and sounds. E-Prime allows the researcher to implement experiments in a fraction of the time required by previous products, or by programming from scratch.
E-Prime User’s Guide Chapter 1: Introduction 1.3 Installation Options 1.3.1 Full Installation The full installation provides the entire suite of E-Prime applications. The table below lists the applications included with the full installation.
E-Prime User’s Guide Chapter 1: Introduction equivalent to a Subject Station or Run-Time Only install, and the E-Prime Analysis and Data File Utilities option is ideal for just merging and analyzing data. During installation, the installation program will prompt the user for the specific applications to be installed. Check all of the applications to be installed, and leave unwanted applications unchecked. The Description field lists the components included with a selected option.
E-Prime User’s Guide Chapter 1: Introduction 1.4.1 Single User / Multi-Pack License A single user license allows the user to develop experiments on one computer at a time. The hardware key must be connected during installation of E-Prime, and while developing experiments within E-Studio. E-Studio will not load if the hardware key is not connected. However, the run-time application (E-Run) is not copy protected.
E-Prime User’s Guide Chapter 1: Introduction accessible. Once E-Prime has been installed, the serial number can also be found in the About E-Studio dialog box located on the Help menu. Users MUST provide the serial number for technical support. 1.6.4 Sharing pre-developed programs E-Prime license owners are free to distribute any files they create through use of the system.
E-Prime User’s Guide Chapter 1: Introduction a great difference in the appearance of the interfaces. By adhering to Windows standards, EPrime has a more familiar look and feel, and will ease the transition from one tool to the other. As an analogy, MEL Professional can be contrasted with E-Prime in the same way that MS-DOS can be contrasted with Windows.
E-Prime User’s Guide Chapter 1: Introduction “Stimulus” attribute rather than {T1}). Other tasks involving the INSERT Category that are very cumbersome in MEL Professional are made much easier by the List object in E-Prime, such as sampling from more than one list on a single trial, sampling multiple times from the same list on a single trial, and setting different randomization schemes for different sets of data.
E-Prime User’s Guide Chapter 1: Introduction the format of the WAV files (e.g., 11,025Hz, 8 Bit, Mono). Most video and audio cards offering DirectX support are compatible with E-Prime. Other restrictions imposed by MEL Professional are alleviated by E-Prime. Reaction times are no longer restricted to a maximum integer value of 32767ms, and experiments are no longer restricted to a maximum of three levels (i.e., Session, Block, Trial). E-Prime allows for up to 10 levels in the experiment structure (e.g.
E-Prime User’s Guide Chapter 1: Introduction Because the two products are fundamentally different, it is strongly recommended that even the most experienced PsyScope user work through the Getting Started Guide as an introduction to EPrime. PsyScope users who have spent a few hours working with Windows programs will quickly realize that many aspects of the E-Prime interface are simply echoes of Windows metaphors.
E-Prime User’s Guide Chapter 1: Introduction modules. These modules replace the methods of PsyDat and PsySquash with the more familiar metaphor of the Excel spreadsheet. Users of PsyDat who also know Excel will simply give up thinking about data analysis through PsyDat and switch to thinking in terms of Excel, as implemented by E-Merge and E-DataAid.
E-Prime User’s Guide Chapter 2: Using E-Studio Chapter 2: Using E-Studio This chapter describes the general methods of implementing an experiment in E-Prime. Note, Appendix B-Considerations in Research provides an overview of experimental research concepts without reference to E-Prime. This chapter assumes the user has worked through the concepts of experimental design and the Getting Started Guides for each of the applications within EPrime.
E-Prime User’s Guide Chapter 2: Using E-Studio 2.2 Stage 1: Conceptualize and Implement the Core Experimental Procedure The goal of this stage is to get the basic procedure implemented to the point where the experiment presents at least two different instances of the trial procedure. Be clear on the trial procedure and what data are to be collected. We will first give an overview of the steps and then give specific instructions for performing the steps.
E-Prime User’s Guide Chapter 2: Using E-Studio 2.2.2 Step 1.2: Create a folder for the experiment and load E-Studio We recommend developing the experiments in the standard directory “My Experiments” on the root directory. We suggest that the experiment be placed in a folder named for the experimental series (e.g., C:\MyExperiments\LexicalDecision) and that the experiment name include a number for the version of the experiment (e.g., LexicalDecision001). 2.2.3 Step 1.
E-Prime User’s Guide Chapter 2: Using E-Studio For example, in the lexical decision experiment, the core experimental procedure was described in the abstract: The subject will be presented with a fixation (+) displayed in the center of the screen for one second. Then a probe display will present a letter string stimulus in the center of the screen for up to 2 seconds.
E-Prime User’s Guide Chapter 2: Using E-Studio For the lexical decision experiment, the fixed and varying properties can be summarized in the following table: Object Fixed Properties Varying Properties Fixation • • • • • • • • • • • • Probe Present “+” in the center of the screen Duration = 1 second (default) Forecolor = black (default) Background color = white (default) Display in center of the screen (default) Duration = 2 seconds Input keys = “1” and “2” Terminate display upon response Forecolor
E-Prime User’s Guide Chapter 2: Using E-Studio keyboard is designated as the Input Mask device, the allowed response keys (Allowable field) are 1 and 2, and the Correct field is set to refer to the CorrectResponse attribute (defined in the DesignList). The End Action is set to the “Terminate” option to terminate the display when the subject responds. These properties are set on the Duration/Input tab of the Probe TextDisplay object (see arrows below). 2.2.6 Step 1.
E-Prime User’s Guide Chapter 2: Using E-Studio Why doesn’t E-Prime simply log everything? Well it could, and technically, if Data Logging is set to Standard on every object in the experiment, it would. However, logging everything greatly expands the data that is stored in an experiment and, more seriously, increases the number of variables to go through when analyzing an experiment.
E-Prime User’s Guide Chapter 2: Using E-Studio Press the “1” or “2” key, the text string will disappear, and the experiment will go to the next trial. Note, each experiment run begins by asking for the subject number and session number (not shown in this example). 2.2.8 Step 1.8: Verify the data logging of the core experiment An experiment is only useful if the critical data are recorded for later analysis. Be clear about what expectations to see as input data for the analysis.
E-Prime User’s Guide Chapter 2: Using E-Studio implementing the specified feature of the lexical decision experiment on a computer using EPrime. We recommend working through the Getting Started Guide for creating an E-Prime experiment prior to performing Stage 1. A completed version of the experiment at each stage described in this chapter is included with the installation (default installation is C:\My Experiments\Tutorials\Using E-Studio Stages).
E-Prime User’s Guide Chapter 2: Using E-Studio 2.3.2.2 Load E-Studio E-Studio is the application in E-Prime that is used to design an experiment. The E-Prime Getting Started Guide shows how to load E-Studio and open a file. Launch E-Studio, and see a screen such as the following: For this example, open a blank experiment and use the File menu Save As option to save the experiment as LexicalDecision001 in the C:\My Experiments\Lexical Decision folder. Most experiments go through many variations.
E-Prime User’s Guide Chapter 2: Using E-Studio 2.3.3 2.3.3.1 Perform Step 1.3: Specify the core experimental design Create and name the List object The independent variables, stimuli, and expected responses are generally specified on a List object. Drag a List object from the Toolbox to the SessionProc timeline. Rename the List1 object to DesignList by clicking on List1, pressing the F2 key (to enter Edit mode) and typing in a new name for the object. The Structure view appears as the following: 2.3.3.
E-Prime User’s Guide Chapter 2: Using E-Studio 2.3.3.4 Create the Procedure The Procedure attribute specifies what procedure to run for the selected condition. In this case, set it to TrialProc as shown in the figure below. After entering “TrialProc” in the Procedure attribute column, E-Studio will indicate that TrialProc has not yet been created and will ask to create TrialProc. Answer “yes” to this prompt. At the end of step 1.
E-Prime User’s Guide Chapter 2: Using E-Studio the Fixation and the Probe display objects, click the TextDisplay object icon in the Toolbox and drag two TextDisplays to the TrialProc. The figure below shows both the Structure view and the TrialProc after putting the TextDisplays on the TrialProc and renaming them appropriately. 2.3.5 Perform Step 1.
E-Prime User’s Guide Chapter 2: Using E-Studio object (in the Structure view) to open it in the Workspace, and click the Property pages tool button (top left corner of the Probe window) to open the Property pages. Select the Duration/Input tab by clicking on it. Then, set the fields as illustrated below. Enter “2000” in the Duration field. To specify the input devices, first click the Add button in the Input Masks list (lower left) to add an input device (e.g., Keyboard or Mouse).
E-Prime User’s Guide Chapter 2: Using E-Studio This includes the OnsetDelay and DurationError properties, which list timing data to check timing precision (see Chapter 3 - Critical Timing). 2.3.6.2 Set specific logging as needed On the Logging tab, set the logging to specific needs. Many of the properties of the object are presented in a list, and are arranged in categories (Dependent Measures, Time Audit, etc.).
E-Prime User’s Guide Chapter 2: Using E-Studio generated during the compiling process, a message indicating the successful generate is displayed in the Output window. If errors occur during generation, an error dialog is displayed, and the error message is sent to the Debug tab in the Output window. The error message will indicate the line in the script at which the error occurred. In addition, the Script window opens to display the line at which the error was encountered.
E-Prime User’s Guide Chapter 2: Using E-Studio However, subjects don’t always follow the instructions, so it is necessary to test the deviant cases as well. For example, what happens when a subject presses a key that is not a valid response key, or perhaps does not respond at all? In the current example, pressing the wrong key or a non-response will not terminate the display, but the stimulus display will terminate when the maximum duration for the stimulus object is reached.
E-Prime User’s Guide Chapter 2: Using E-Studio Until a data file is opened, no data can be displayed. Use the Open tool button, to open the data file for the experiment. The data file name is determined by concatenating the Experiment name, the subject number, and the session number. Following the suggestion for naming the experiment and running as subject #1, session #1, the data file would be named LexicalDecision001-1-1.edat. 2.3.8.
E-Prime User’s Guide Chapter 2: Using E-Studio . Verify that the conditions, stimuli, and correct responses (i.e., independent variables) are logged as expected. 2.3.8.4 Find the dependent variables and verify they are set reasonably Verify the logging of the dependent measures. The RESP property is the actual response entered, and is logged as NULL for a non-response.
E-Prime User’s Guide Chapter 2: Using E-Studio 2.4 Stage 2: Elaborate the Trial Procedure Note: This section builds on the experiment created during the previous section. A finished version of LexicalDecision001.es is located in the C:\My Experiments\Tutorials\Using E-Studio Stages directory. The goal of Stage 2 is to elaborate the basic Fixation-Probe trial procedure.
E-Prime User’s Guide Chapter 2: Using E-Studio 2.4.2 Add instructions to Fixation and Probe displays Add instructions to the Fixation and Probe objects in the form of constant text (i.e., it will not vary from trial to trial). Open the Fixation object, add four blank lines following the fixation character, and type the text, as in the display below, to remind the subject of the response keys. Open the Probe object and set the height of the display area (Frame tab) to 25%.
E-Prime User’s Guide Chapter 2: Using E-Studio Add an independent variable for coding PrimeType. Open the DesignList, add an attribute, and name it PrimeType. Enter the values for PrimeType to be “word” and “non-word” as illustrated below: Finally, set the frame height for the Prime object to 25% so that the instructions from the Fixation are not overwritten.
E-Prime User’s Guide Chapter 2: Using E-Studio 2.4.4 Add Feedback Add a FeedbackDisplay object as the last event in the TrialProc, and rename it to Feedback. Accept the standard feedback text settings for correct, incorrect, and non-responses. From the dropdown box, select the Feedback object, and click the Properties tool button to set the properties for the parent object. Set the Duration for the Feedback object to 2000ms.
E-Prime User’s Guide Chapter 2: Using E-Studio 2.4.5 Run and verify the Get Ready, Prime, and Feedback objects Save the experiment, compile it, and run it to verify that the new additions to the trial procedure work as expected for all possible subject responses. Remember to test deviant as well as expected cases (e.g., correct, incorrect, and invalid key responses). 2.
E-Prime User’s Guide Chapter 2: Using E-Studio 2.5.1.2 Method B – Use of Nested Lists Note: A finished version of Stage3-MethodB-LexicalDecision001.es is located in the C:\My Experiments\Tutorials\Using E-Studio Stages directory. Nested lists provide a method to organize a list of items (e.g., words and non-words) and reference that organized list in the List object used to run the Procedure. This experiment might have lists of words and non-words from which stimuli are sampled.
E-Prime User’s Guide Chapter 2: Using E-Studio of selection (e.g., sequential, random) is determined by the properties of the WordList. Let's assume the second row of the WordList is selected (ID = 2 with Word = dog). The variable [Word] is set to “dog," then the experiment returns to the DesignList to set the other attributes. In the DesignList, the Stimulus attribute refers to the Word attribute using bracket notation (i.e., [Word]).
E-Prime User’s Guide Chapter 2: Using E-Studio This list may then be edited to fill in the appropriate values (i.e., sort the columns in order to use the intelligent fill feature within Excel), reorder levels, or remove certain levels. In the spreadsheet created by the Factor Table Wizard, rearrange the columns, and enter the values for the Stimulus attribute column. Once the list is completed, copy the values in the table (minus the headers) and paste them into a List in the experiment.
E-Prime User’s Guide Chapter 2: Using E-Studio 2.5.2 Set the weights To change the relative frequency of trial types, change the weight of the exemplars. In this example, this is done by setting the values for the Weight attribute in the DesignList. Set the weights for the exemplars in the Word condition to “1,” and the weights for the NonWord exemplars to “2,” making the ratio of non-word to word stimuli 2 to 1. 2.5.
E-Prime User’s Guide Chapter 2: Using E-Studio The table below illustrates how a List with three elements (values A, B, and C) might be sampled using the different methods described above. The last three methods (Counterbalance, Offset, and Permutation) select base modulus of the subject number by number of condition sequences for the subject number.
E-Prime User’s Guide Chapter 2: Using E-Studio 2.5.4 Test Save the experiment, compile, and run to verify that the new additions to the DesignList work as expected. There should now be 24 trials in random order with non-words occurring twice as frequently as words. 2.6 Stage 4: Add Block Conditions Note: This section builds on the experiment created during the previous section. A finished version of Stage3LexicalDecision001.
E-Prime User’s Guide Chapter 2: Using E-Studio 2.6.1.2 Add a block attribute In the BlockList, add an attribute and rename it PrimeDuration. This attribute will be used to vary the duration of the prime across blocks. Click the Add Level tool button to add one level. Complete the BlockList to define the levels of the PrimeDuration attribute as 500 and 1000 milliseconds. 2.6.1.
E-Prime User’s Guide Chapter 2: Using E-Studio 2.6.3 Add block instructions In the Toolbox, click the TextDisplay object icon, and drag a TextDisplay object to the BlockProc as the first event in the procedure. Rename the TextDisplay to BlockInstructions. Type the following as the text for the BlockInstructions object. In the instructions, the [PrimeDuration] attribute reference informs the subject what the delay will be for each block. The subject is instructed to press the spacebar to begin the block.
E-Prime User’s Guide Chapter 2: Using E-Studio Like the BlockInstructions, the Introduction object instructs the subject to press the spacebar to continue. In the properties for the Introduction object, 1) set the Duration equal to “-1” to wait until a response is entered, 2) set the Input Mask to allow keyboard input, 3) set the Allowable field as the spacebar (i.e., {SPACE}), and 4) set the End Action to “Terminate” upon response from the subject.
E-Prime User’s Guide Chapter 2: Using E-Studio 2.6.6 Special notes: Multiple methods to divide a design between levels Multiple methods may be used to execute different procedures during different blocks. The last task illustrated using a block level attribute to set a parameter of an object executed in the trial procedure (the PrimeDuration). Two other common procedures are to pass a nested list, or to pass an experimental procedure. These are advanced features providing a great deal of flexibility.
E-Prime User’s Guide Chapter 2: Using E-Studio The next step is to create the three List objects to which the DesignList refers (i.e., AnimalList, FruitList, NonWordList). Each list would necessarily include the ListStim attribute, which would define the text strings to be used as the stimuli. AnimalList, FruitList, and NonWordList should be created in the Unreferenced E-Objects folder.
E-Prime User’s Guide Chapter 2: Using E-Studio However, because the ListType attribute is being used to vary the selection of words from two List objects, and the value of ListType is resolved only at run-time, E-Studio is unable to place the AnimalList and the FruitList objects in the structure. The ListType attribute is placed in brackets below the DesignList, and is preceded by a to indicate that the nested List is varying.
E-Prime User’s Guide Chapter 2: Using E-Studio Figure 1. Two stimuli assigned to a single attribute value. 2.6.6.2 Figure 2. Two stimuli assigned to separate attributes. Use of block Procedure to pass in the trial Procedure Note: A finished version of Stage4-ChangeTrialProc-LexicalDecision001.es is located in the C:\My Experiments\Tutorials\Using E-Studio Stages directory. Run different trial Procedures during different blocks.
E-Prime User’s Guide Chapter 2: Using E-Studio Notice that the Browser lists MaskTrialProc as being unreferenced. When PrimeTrialProc was copied, the copy was created in the Unreferenced E-Objects folder. Also notice that the renaming of TrialProc to PrimeTrialProc resulted in the updating of all references to TrialProc (e.g., in the Structure view and in the DesignList).
E-Prime User’s Guide Chapter 2: Using E-Studio The results of this modification are displayed in the Structure view below. Since the DesignList refers to the [TrialProcName] attribute as the value in the Procedure column, the Structure view shows a “?” as the procedure called by the DesignList, and the MaskTrialProc and PrimeTrialProc reside in the Unreferenced E-Objects folder. At run-time, the value for the TrialProcName attribute is resolved, and the appropriate Procedure is executed.
E-Prime User’s Guide Chapter 2: Using E-Studio adding a PracticeBlockList, a PracticeMode attribute to track the practice mode, some userentered script to score the accuracy, and repeating the practice block if the accuracy criterion is not met. 2.7.1 Duplicate BlockList in the Browser We want to have a PracticeBlockList very similar to the BlockList. By duplicating the BlockList we have a copy that can be modified without affecting the BlockList.
E-Prime User’s Guide Chapter 2: Using E-Studio 2.7.2.2 Add PracticeMode attribute to block level List objects Open the PracticeBlockList and the BlockList in the Workspace. Add an attribute named PracticeMode to each List object. Set the value for PracticeMode to “practice” for the PracticeBlockList, and to “real” for the BlockList. 2.7.
E-Prime User’s Guide Chapter 2: Using E-Studio The script above examines the value of Feedback.ACCStats.Mean (calculated automatically by the Feedback object) to determine if the subject achieved 80% accuracy. If this value is greater than 80%, the practice trials terminate and the experiment continues with the real trials (i.e., the next object in the SessionProc is the BlockList).
E-Prime User’s Guide Chapter 2: Using E-Studio 2.7.3.3 Add the EndPrac object to the SessionProc It is important to inform the subject whether they have met the accuracy criterion. We do this by adding the EndPrac object to display the text determined by the preceding CheckAccuracy Inline object. Add a TextDisplay object to the SessionProc following the CheckAccuracy object.
E-Prime User’s Guide Chapter 2: Using E-Studio the Duration tab on the Prime object. Note the Data Logging (Time Audit Only), Timing Mode (Event), and PreRelease (0ms) fields. These fields must be checked for each of the critical objects in the trial procedure. The “Time Audit Only” option in the Data Logging field logs the duration information for later analysis (i.e., OnsetTime, OnsetDelay, DurationError).
E-Prime User’s Guide Chapter 2: Using E-Studio To terminate the BlockList, the same procedure would be used with a BlockList.Terminate command. 2.9 Stage 7: Testing the Experiment Note: This section builds on the experiment created during the previous section. A finished version of Stage6LexicalDecision001.es is located in the C:\My Experiments\Tutorials\Using E-Studio Stages directory.
E-Prime User’s Guide Chapter 2: Using E-Studio Ø Verify that the correct number of trials and blocks are being run, and that the session level information is logging correctly (i.e., subject number, session number, etc.). Ø Determine that the data file reflects the correct number of observations for each cell in the design. For example, if a 2x3 design is running 5 repetitions of each cell, the data file should display 30 trials including 5 trials for each of the 6 conditions.
E-Prime User’s Guide Chapter 2: Using E-Studio 2.10 Stage 8: Running the Experiment Once experiment development is completed and you have thoroughly tested the experiment and examined the data file to determine that the necessary information is logging appropriately, data collection is ready to begin. With a subject-ready experiment, E-Studio is no longer needed to launch the E-Run application. 2.10.
E-Prime User’s Guide Chapter 2: Using E-Studio After the run is complete, E-Run will return to the window displaying the EBS file, and will display a dialog indicating the successful termination of the script. 2.10.2 Running on multiple machines E-Prime must be installed locally in some manner on every machine on which its use is intended. However, the entire E-Prime system need not be installed on machines to be used only for data collection.
E-Prime User’s Guide Chapter 2: Using E-Studio E-Prime collects only single subject data files, which include the EDAT extension. Thus, for analysis, the single subject data files must be merged into a master file. The E-Merge application is used for this purpose (refer to Stage 9, this chapter). If data is being collected on multiple machines, the EDAT files must be copied or moved to a common location for merging, unless the data collection machines are networked. 2.
E-Prime User’s Guide Chapter 2: Using E-Studio To merge individual data files, navigate to the folder containing the data files using the Folder Tree, select the files to be merged in the File List view, and click the Merge button. Refer to the E-Prime Getting Started Guide, and Chapter 5 – Data Handling in the User’s Guide for more detailed information. In many circumstances, data files may be saved in different folders.
E-Prime User’s Guide Chapter 2: Using E-Studio 2.11.2 Checking data condition accuracy and data quality Once the data has been merged to a master file, the file should be checked to verify the data it contains, and that the values are within expected ranges. Rather than a checking of the logging of variables (i.e.
E-Prime User’s Guide Chapter 2: Using E-Studio E-DataAid works much like Excel, allowing the addition of columns (i.e., variables) and modification of cell values. For example, to edit the value in a cell, place the cursor in the appropriate cell, delete the current value, and simply type the new value. To select a column, click the column header, and to move that column, click and drag the header to the new location.
E-Prime User’s Guide Chapter 2: Using E-Studio 2.11.3 Analysis and export of data E-DataAid also allows the formatting and exporting of raw data, a subset of the data, and data tables (e.g., Mean RT x Condition). 2.11.3.1 Exporting raw data To export the raw data, use the Export command in the File menu, or click the Export tool button. The Export command allows the output format to be specified for a particular statistical package. Formatting for several common software packages (e.g.
E-Prime User’s Guide Chapter 2: Using E-Studio The Arrange Columns command allows the user to choose whether to hide or display specific columns in the spreadsheet, and to organize the order of the displayed columns. The Filter command allows the user to limit the display to certain values within a specific variable (e.g., only correct responses). To set a filter, choose the variable (i.e., column) name and the type of filter to apply. Then select the specific values to include (i.e.
E-Prime User’s Guide Chapter 2: Using E-Studio Once the columns are arranged and/or filters are applied, the export operation may proceed as usual, with only the displayed subset of the complete data file being exported (refer to section 2.11.3.1-Exporting Raw Data). 2.11.3.3 Creating and exporting tables A summary table of values (e.g., MeanRT x Condition) may be exported using the Analyze feature. The Analyze command may be invoked via the Tools menu, or by clicking the Analyze tool button.
E-Prime User’s Guide Chapter 2: Using E-Studio In addition to an export, the table may be copied directly into Excel, or to the clipboard for saving in an alternative software package.
E-Prime User’s Guide Chapter 2: Using E-Studio 2.12 Stage 10: Archiving Experiments and Results 2.12.1 What files to store For the purposes of replication, collaboration, and verification, it is necessary to keep thorough records of experiment files and methods. The files listed below should be archived in order to investigate, share, or replicate an experiment: File Name Description ExperimentName.ES Experiment specification file ExperimentName.
E-Prime User’s Guide Chapter 2: Using E-Studio 2.13 Stage 11: Research Program Development Note, some users may include copyright notices in their experiments. Be respectful of the constraints authors place on sharing script, and always give credit for script used. 2.13.1 Modifying experiments When modifying experiments, it is important to maintain consistency as much as possible.
E-Prime User’s Guide Chapter 2: Using E-Studio section 2.12.1 and the following section for definitions of licenses, permissible actions according to the type of license, and files used by each type of license. 2.13.2.1 Licenses The full E-Prime license permits use of each of the applications available within the E-Prime suite of applications.
E-Prime User’s Guide Chapter 2: Using E-Studio Another suggestion is to create a package file for procedures used repetitively (e.g., criterionbased exit of a procedure, contingent branching). Package files from a library may be inserted into new experiments in order to avoid wasted time regenerating existing script. Examples of package files might be the N-Back memory task item selection, psychophysical threshold procedures, or moving window text presentation.
E-Prime User’s Guide Chapter 3: Critical Timing Chapter 3: Critical timing in E-Prime - Theory and recommendations 3.1 Executive Summary of E-Prime Timing Precision and Implementation Methods Psychology Software Tools, Inc. has tested E-Prime on a wide range of single processor desktop and laptop computers using Pentium and Celeron series processors from Intel, and Athlon series processors from AMD. Test machines varied in speed from 60MHz through current generation processors in the GHz range.
E-Prime User’s Guide Chapter 3: Critical Timing millisecond timing or reliable refresh detection, necessitating the running of the diagnostic test and subsequent, potential tuning of the system. E-Prime supports basic and advanced timing needs. The experimenter must be able to identify the true critical timing needs of an experiment and know how to analyze the data in order to verify and report the timing precision.
E-Prime User’s Guide Chapter 3: Critical Timing accurately, even when the computer or operating system code reports timing inaccurately. However, you need to take the time to understand what precision you need, recognize artifacts in your timing data, and apply methods to reduce or eliminate errors. In section 3.4, we give a brief review of the tests of timing accuracy we are performing. You can download some of these tests from the Psychology Software Tools web site and run them on your own computer.
E-Prime User’s Guide Chapter 3: Critical Timing Modern multi-tasking operating systems (e.g., Windows, Mac OS, Unix) will not allow exclusive and continuous execution of any process, because the operating system must take cycles to perform critical functions (e.g., virtual memory management). No program running on a common desktop operating system can deliver accurate measurements at every millisecond (i.e., a 0% miss tick rate).
E-Prime User’s Guide Chapter 3: Critical Timing 2 to read a microsecond precision clock resulted in variance in the range of 200ms , with clock miss rates of 58% on a Pentium 120MHz computer and 47% on a Pentium 500MHz. When running similar tests under E-Prime on the same machines, the clock miss rate was reduced to less than 0.1%. We encourage the reader to perform a simple test to determine the accuracy of the timing of any experiment presentation software that claims to provide millisecond accuracy.
E-Prime User’s Guide Chapter 3: Critical Timing The reporting of the refresh rate by Windows is "invalid". On this particular hardware, if you set the Refresh Rate at 60Hz for the 1280x1024 resolution on the Settings tab, Windows will always display 60Hz while the actual refresh rate is 75.3Hz. This is because Windows views the settings as a "request" and allows the display device driver to provide its best approximation to the request.
E-Prime User’s Guide Chapter 3: Critical Timing Intended and Actual Display Duration Without E-Prime 1000 Display Duration (ms) 900 800 700 600 Intended 500 Session 1 400 Session 2 300 200 100 0 1 26 51 76 101 126 151 176 Image number Figure 1. Actual display durations for displays run on 2 sessions relative to the intended (200ms) duration. The program’s task is simple -- display each image for 200ms while the microsecond clock is being read.
E-Prime User’s Guide Chapter 3: Critical Timing The second and third faults in the timing data in Figure 1 are related to the spikes in timing durations. Why are some delays very long, and why do they occur at random intervals, changing even if run under exactly the same conditions? The spikes are due to the Windows operating system taking control of the machine and halting the program to perform various administrative and/or “clean-up” activities.
E-Prime User’s Guide Chapter 3: Critical Timing Intended and Actual Display Duration - E-Prime 1000 900 Display Duration (ms) 800 700 600 Intended 500 Actual 400 300 200 100 0 0 25 50 75 100 125 150 175 Image Number Figure 2. Intended versus actual display time in E-Prime for a 200ms display. E-Prime can present displays at a very high rate (e.g., new image every 12ms or less on appropriate hardware, see section 3.4.2.3).
E-Prime User’s Guide Chapter 3: Critical Timing Figure 3. Video display refresh cycle for a 1024x768 display with a refresh rate of 71.4Hz (14ms refresh duration). The top line of the display is line 0, and the bottom line is 767. Each pixel is displayed once every 14ms. To calculate the refresh duration in milliseconds given the refresh rate specified in Hz, use the following equation: Refresh Duration (ms) Refresh Duration Refresh Duration = 1000 / Refresh Rate (Hz) = 1000 / 71.4 = 14.
E-Prime User’s Guide Chapter 3: Critical Timing Pixel Intensity During a Display Sequence Relative Display Intensity 1 Time of Pixel Activation 0.9 + 0.8 CAT *** 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 Time of Write to Video Memory 0 + 7 14 CAT 21 28 35 42 49 *** Time (ms) Figure 4. Pixel activation of center of display for “+” presented at 0ms, “CAT” presented at 14ms, and “***” presented at 28ms. The subject actually first sees “+” at 7ms, “CAT” at 21ms, and “***” at 35ms.
E-Prime User’s Guide Chapter 3: Critical Timing Display Sequence Interaction with Refresh Cycle 1 Time of Pixel Activation Relative Display Intensity 0.9 + 0.8 *** *** 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 Time of Write to Video Memory 0 + 7 CAT 14 *** 21 28 35 42 49 Time (ms) Figure 5. Presenting displays for less than a refresh cycle produces partial displays. The arrows on the bottom show writing of the stimuli "+", "CAT" and "***" to video memory at 0, 5, and 10ms respectively.
E-Prime User’s Guide Chapter 3: Critical Timing Recall that Figure 2 illustrated a small cyclic variation of the stimulus duration. Figure 6 shows an enlarged view of the intended and actual time measured in E-Prime. 210 205 200 Intended Time 195 E-Prime 200 ms 190 E-Prime 15 Refreshes 185 E-Prime 14 Refreshes 15 13 11 9 7 5 3 180 1 Display Duration (ms) E-Prime Stimulus Display Duration Options Image Number Figure 6.
E-Prime User’s Guide Chapter 3: Critical Timing In response to the Measuring, Reporting, and Debugging problem, E-Prime has a built in Time Audit logging capabilities available for every object. When an object takes an action that could impact a subject (e.g., display, response input), E-Prime logs the time of that event, and this information may be output to the analysis stream for easy recording and analysis.
E-Prime User’s Guide Chapter 3: Critical Timing or synchronizing timing with external equipment (e.g., brain wave monitoring), it is important to understand timing concepts described here to accurately specify the experiment. In this section, we describe five techniques for achieving accurate and precise timing in computerized research. Each of these techniques is grounded on a concept about timing and computers that may be novel to the reader.
E-Prime User’s Guide Chapter 3: Critical Timing Lets review the example above in detail and assume a 50ms PreRelease time is specified. In the example, the preparation or setup time was 30ms. So, after 30ms the first stimulus was presented to the subject. When PreRelease is used, the second stimulus is selected and prepared for presentation while the first stimulus is still being presented. By 60ms, the second stimulus is prepared.
E-Prime User’s Guide Chapter 3: Critical Timing go, and unlikely to be touched by the operating system. The code for monitoring when to display the stimulus is in a tight loop to keep execution short and keep the code in memory. If the operating system takes control and steals time that is less than the PreRelease time, the tight code segment of putting up the display will not be affected.
E-Prime User’s Guide Chapter 3: Critical Timing Log Post Response Log Before Response Figure 8. Interaction of extended response interval. In Log Post Response (above), data from response has been collected before recording for logging (shown as “”$”). In Log Before Response, the logging occurs before the extended response interval is completed and hence response events may not be recorded.
E-Prime User’s Guide Chapter 3: Critical Timing in E-Prime are fixed for the session of the experiment and are not simply numbers of the desired display times. This relates to Problem 3 above (Section 3.2.3), which explained that interactions with the visual display are only effective relative to refresh cycles. The concept of presenting displays as multiples of the refresh cycle has several implications.
E-Prime User’s Guide Chapter 3: Critical Timing Figure 9. Timing diagram showing the effects of using event and cumulative timing modes on a stimulus presentation sequence. Event Mode Timing In Event mode, delays in the onset of an event will not affect the specified duration of the event. This results in a delay of the onset of all subsequent events due to the error, and an accumulation of timing delay across events. For example, assume you wanted to present 5 stimuli in sequence for 100ms each.
E-Prime User’s Guide Chapter 3: Critical Timing There may also be an interruption in the timing sequence if a stimulus is terminated by a subject response (e.g., one of its input masks has its End Action property set to Terminate). When this occurs, E-Prime assumes the user wants the next stimulus to occur as soon as possible after the current event is terminated. Otherwise the End Action property would have been set to (none).
E-Prime User’s Guide Chapter 3: Critical Timing If Cumulative timing mode was in use, the duration for each display would be shortened so that the end of the display time would always occur as close to 100ms boundaries as the hardware allows. In Cumulative mode, the second display would start looking for the vertical blanking at 100ms (rather than at 106.83ms). In Cumulative mode, the average display duration would be 100ms with a standard deviation of 3.95ms.
E-Prime User’s Guide Chapter 3: Critical Timing hidden or filtered using the E-DataAid appliction, the user should consider the long-term benefits of having the extra timing data available should the timing of the experiment ever be challenged or require re-examination. The table below is an example of the output of an analysis in E-DataAid (the data editing and analysis application within E-Prime).
E-Prime User’s Guide Chapter 3: Critical Timing mode. In the Cumulative onset-to-onset, the times are a fixed constant dip of one refresh occurring about every 25 displays. The OnsetDelay increases until the display passes a full refresh cycle, and then there is a shortened display by one refresh (100ms versus 86ms). This increase in the OnsetDelay occurs because of the refresh rate essentially being an approximation that is only accurate to some number of significant digits of precision.
E-Prime User’s Guide Chapter 3: Critical Timing Max Measured Pause by Priority Max Duration of Pause (ms) 140 120 100 80 Normal Mode E-Prime High Priority 60 40 20 25 23 21 19 17 15 13 11 9 7 5 3 1 0 Sequential Run Figure 11. Measured maximum duration of a pause in experiment execution in normal and high priority mode over 25 runs of a 10,000ms timing interval. In E-Prime, running in high priority mode on a slow (120MHz) machine typically results in maximum single delays of 3ms.
E-Prime User’s Guide Chapter 3: Critical Timing environment. Each crystal, while very precise and accurate, will still have some very small degree of error inherent within it (e.g., some number of parts per billion). The exact degree or amount of error is unique to each individual crystal.
E-Prime User’s Guide Chapter 3: Critical Timing 3.4.1 Step 1. Test and tune the experimental computer for research timing Desktop computers come in thousands of hardware and software configurations. Most of these can be tuned to provide millisecond precision as defined in section 3.2. However, there is a serious risk that the current configuration of the computer cannot support millisecond precision.
E-Prime User’s Guide Chapter 3: Critical Timing timing precision is unnecessary for most experiments. Generally, experimental paradigms have a specific set of critically timed segments that must be carefully checked and verified, while the rest of the events of the experiment do not require the same level of precision (e.g.
E-Prime User’s Guide Chapter 3: Critical Timing The durations were simply specified as 20, 60 and 100ms without regard for any potential influences (e.g., refresh rate). The gray areas of the table show the actual length of time the stimuli were displayed. Notice that the actual durations are integer multiples of the respective refresh periods (rounded up) so that they accommodate the specified duration (i.e., 20, 60 or 100ms). For example, for a refresh rate of 60.15Hz, the refresh period would be 16.
E-Prime User’s Guide Chapter 3: Critical Timing Stimulus Duration to Specify = (16.63ms/cycle * 3 cycles) –10ms = 49.89ms – 10ms = 39.89ms rounded 40ms Since E-Prime only accepts durations as integer numbers of milliseconds we round 39.89ms up to 40ms. Continuing with the example, if the stimulus duration is set to 40ms, the fourth vertical blanking (hardware signal indicating the beginning of the next refresh cycle) would be expected to fall at 49.89ms.
E-Prime User’s Guide Chapter 3: Critical Timing millisecond) are unlikely to result in a missed detection of a refresh. In contrast, if duration is set to the expected time of the refresh, in half of the cases the refresh would occur before starting to look for it. Think of the 10ms rule as providing robustness to account for the typical variability between cards of the same model (0.1ms), E-Prime variability (0.
E-Prime User’s Guide Chapter 3: Critical Timing Figure 13. Location of E-Prime housekeeping operations. Note, durations specified in labels will vary with the complexity of the tasks being performed (e.g., amount of data being logged, flushing of data to log file, number of list rows being reshuffled, etc.). 3.4.2.3 Select a basic critical timing paradigm There are five basic critical timing paradigms we will describe.
E-Prime User’s Guide Chapter 3: Critical Timing Timing Paradigm 3: Critical sequence of events with varying duration of Probe This paradigm is a variant on Paradigm 2 in which the duration of an event in a sequence varies between trials (e.g., the duration of the probe would be 14, 28 or 42ms – integer multiples of the refresh rate). This paradigm includes a parameter in a List object to set the duration as an independent variable. The Durations must be based on the refresh rate of the video mode.
E-Prime User’s Guide Chapter 3: Critical Timing Duration field for the object controlling the event. The response time will be measured from the onset time of the object presenting the critical stimulus and enabling the response (e.g., the Probe display), to the time of the response. The TimingParadigm1 experiment shows an example of such a paradigm (see Figure 14). The critical time segment is just the Probe object.
E-Prime User’s Guide Chapter 3: Critical Timing In the trial procedure, the Probe stimulus is removed from the screen by the Feedback object (i.e., the Feedback is displayed over top of the Probe, thus effectively removing it from the display). The variable Probe.RT stores the reaction time data (in milliseconds) for the response collected by the Probe object. Note that the timing is based on a stimulus that would appear at the top of the screen.
E-Prime User’s Guide Chapter 3: Critical Timing The Fixation and Probe objects use PreRelease to provide setup time so the Fixation stimulus can flip to the Probe in a single refresh, and likewise, the Probe can flip to the Mask. The durations should be set to be 10ms less than the calculated time based on the measured refresh rate. The recorded refresh rate for the monitor was 60.16Hz, or 16.62ms. The Expected refresh durations are calculated as follows (using the rule of thumb outline in section 3.4.2.
E-Prime User’s Guide Chapter 3: Critical Timing The Data Logging property in the object’s Property pages (Duration/Input tab) sets the options as to what data will be logged in the data file. For an object performing time-critical presentation but not collecting a response, select Time Audit Only. This logs the OnsetDelay, OnsetTime, and DurationError measures for the object. The Data Logging setting of Standard collects Time Audit values as well as subject response variables (e.g.
E-Prime User’s Guide Chapter 3: Critical Timing TimingParadigm2 Time Audit Data (ms) Probe Mask Fixation Trial OnsetDelay OnsetTime OnsetDelay OnsetTime OnsetDelay OnsetTime Fix-Probe Probe-Mask 1 12 4975 10 5474 10 5574 499 100 2 3 12 17 7768 11342 10 9 8267 11840 9 10 8366 11940 499 498 99 100 4 5 13 17 14317 17425 10 10 14816 17924 9 10 14915 18024 499 499 99 100 6 7 9 17 20334 23259 10 10 20833 23758 9 10 20932 23858 499 499 99 100 8 9 16 13 26434 29659 10 10
E-Prime User’s Guide Chapter 3: Critical Timing Timing Paradigm 3. Critical sequence of events with varying duration of Probe Another common paradigm is presenting displays for varying durations in order to map out a psychological function. For example, mapping the accuracy for words as a function of display duration, with displays being presented at 17, 33, and 50ms. This can be accomplished with a modest variant of Paradigm 2.
E-Prime User’s Guide Chapter 3: Critical Timing With the changes in the TrialList and the Probe display, the experiment can now present the Probe display for a range of durations. It is critical to run the experiment and analyze the presentation data, and verify that the timing precision is what was expected. The following table shows the first ten trials of the experiment, with the mean and SD calculated for the entire set of 24 trials.
E-Prime User’s Guide Chapter 3: Critical Timing 33.24. If matching the Probe to Mask times with the Probe Duration times, the Probe Durations are 10ms less, as expected. An additional check is needed to determine that the durations in each condition were as expected. A pivot table can be generated in Excel to show the results broken down by ProbeDuration. ProbeDuration Mean Probe-Mask S.D. Probe-Mask 7 23 40 16.88 33.25 49.75 0.33 0.43 0.
E-Prime User’s Guide Chapter 3: Critical Timing Figure 20. Timing Paradigm 4 with ellipse over critical events including stimulus selection and the procedure. To present the loop on a fixed schedule, we remove all subject input termination from the trial 14 loop . For example, the trial instructions are now presented once at the beginning of the experiment, rather than in the trial loop.
E-Prime User’s Guide Chapter 3: Critical Timing third at 7000, etc. The Onset Sync property for the displays is still set to vertical blank so that each display will delay until the beginning of the refresh cycle. In Cumulative timing mode, EPrime will compensate for any onset delay by reducing the duration of the display, so that the next display will occur at the next refresh cycle. This reduces cumulative timing error at the expense of increasing between stimulus variability slightly.
E-Prime User’s Guide Chapter 3: Critical Timing Cumulative Timing Error Event versus Cumulative Mode 120 Onset Error (ms) 100 80 60 40 Event Timing 20 Cumulative Timing 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 -20 Trial Figure 21. Timing onset errors for the same presentation sequence run in Cumulative versus Event timing mode Cumulative timing mode has a cost in terms of increased variability in stimulus duration. The standard deviation for the Probe to Mask duration was 3.
E-Prime User’s Guide Chapter 3: Critical Timing However, once a common reference point is established, the two different clocks will still eventually “drift” out of synchronization relative to each other. This timing drift is caused by miniscule timing inaccuracies inherent in each unique hardware clock (see 3.3.1.6 Technique 6: Rescaling clocks to match precision differences).
E-Prime User’s Guide Chapter 3: Critical Timing able to maintain synchronization within a millisecond after 10 minutes. Note that you can rerun the calibration test with a scaling factor applied in order to verify the results of rescaling. Once a scaling factor is computed, the actual rate of drift is minimal as long as both machines are operating at a stable temperature.
E-Prime User’s Guide Chapter 3: Critical Timing Limits on Stimulus Presentation Rates CPU Speed Refresh Rate 450MHz 60.1Hz 266MHz 70.1Hz 120MHz 70.4Hz Target Duration (ms) Observed Duration (ms) 100 83 67 33 100 83 66 33 96 82 55 55 94 80 80 80 17 33 55 80 Note that the 450MHz computer followed the target duration down to 33ms, but could not go below 33ms for the stimuli used in this example. The 266MHz followed until 55ms, and the 120MHz was only able to follow down to 80ms.
E-Prime User’s Guide Chapter 3: Critical Timing 15 a few milliseconds, but enough to occasionally miss the 33ms vertical blanking signal . This results in a delay extended to the next refresh cycle (50ms spikes on images 527 and 584). At image 602 the computer tried to present an image every 17ms. At this duration setting, there was insufficient time to prepare the stimulus, and the onset delay increased to 27ms with occasional spikes to 44ms (skipping to 1 or 2 later refresh cycles).
E-Prime User’s Guide Chapter 3: Critical Timing Read time comparisons for machine speeds Processor Speed Image Loading Method Disk Cache 266MHz 500MHz 35.85ms 0.36ms 18.84ms 0.23ms Figure 25 illustrates the results of running the flashing checkerboard test on a 500MHz computer with a 2x AGP video card. Note the durations for the loads from disk versus loads from the cache. The left side of the figure shows the rates for disk-loads, with disk-loads taking approximately 19ms.
E-Prime User’s Guide Chapter 3: Critical Timing You may download TimingParadigm5 from the PST website (www.pstnet.com) for an example of how an image cache may be created. This experiment uses script to compute and log some of the timing variables and to manipulate the target onset times for each stimulus using the SetNextTargetOnsetTime command in E-Basic.
E-Prime User’s Guide Chapter 3: Critical Timing below 5-6ms (from images 1081 on). A brief look at the plot allows the user to detect a single mismatch in timing over any of the 2160 images presented in this test program. Image Duration and Onset Delay 120 Display Duration (ms) 100 80 Duration 60 Onset Delay Refresh Duration 40 20 0 1 201 401 601 801 1001 1201 1401 1601 1801 2001 Sequential Image Figure 26.
E-Prime User’s Guide Chapter 3: Critical Timing The second error is a mismatch between the assumed refresh rate of the display card and the actual refresh rate. Starting at images 241, there are a large number of spikes in the delay. These indicate timing errors, occurring because the program was specified to run using a 60.1Hz refresh rate but was actually run at 73.1Hz without correction for this difference. The experiment was waiting for a delay at 66.
E-Prime User’s Guide Chapter 4: Using E-Basic Chapter 4: Using E-Basic 4.1 Why Use E-Basic? Although E-Studio is a robust application, E-Basic is the underlying scripting language. Specifically, the graphical design created in E-Studio is translated to E-Basic script when the experiment is compiled or generated. While E-Studio is filled with interesting and clever functionality, chances are that it can be improved to satisfy the end user's specific or custom needs. That is where E-Basic is useful.
E-Prime User’s Guide Chapter 4: Using E-Basic addition to sections for intermediate and advanced users. The goal of this chapter is to get the user accustomed to writing E-Basic script. If this is something that is believed to be beyond present abilities, the following section will recommend some additional sources. 4.1.1 Before Beginning… Before attempting to write any script using E-Basic, a few critical pieces of information must be known.
E-Prime User’s Guide Chapter 4: Using E-Basic examined using the Full tab in the Script window within E-Studio, or by loading an existing EBS file into E-Run. 4.1.1.1 Introduction to Programming Regardless of programming experience, every user should follow the same basic steps when writing script. Design It is critical to thoughtfully plan the desired result, rather than assuming how it will work.
E-Prime User’s Guide Chapter 4: Using E-Basic Test Once the first step is implemented, it MUST be tested thoroughly. If a problem is discovered, it is important to fix it now rather than later. Testing is particularly important in research. Precision testing is described in Chapter 2-Using E-Studio in this volume. Debug Search through the code to find the problem and then correct it. There are many tricks to make debugging less painful than taking a stab in the dark.
E-Prime User’s Guide Chapter 4: Using E-Basic not recommended, since it defeats the purpose of the graphical interface. In addition, E-Studio always overwrites the EBS file each time it generates, which would discard any edits made directly in the EBS file. However, reading through the EBS file is a good way to become familiar with E-Basic and its components. The second and third methods of using E-Basic are contained within E-Studio.
E-Prime User’s Guide Chapter 4: Using E-Basic Essentially, properties store information regarding the behavior or physical appearance of the object. For instance, a TextDisplay object has a Text property, which represents the text to be displayed on the screen. Object.Methods Objects also expose internal routines for programmability called methods. In E-Basic, an object method can take the form of a command or a function. Object.
E-Prime User’s Guide Chapter 4: Using E-Basic 4.2.2.3 Find The Find page allows searching for specific words or phrases within the Help topics. After typing in a word to search for in the Help topics, the topics in which the word appears are listed, as well as additional suggestions to narrow the search. The Help information for a particular topic may be displayed by selecting the topic and clicking the Display button, or by double clicking the topic.
E-Prime User’s Guide Chapter 4: Using E-Basic Section Purpose Syntax Describes the parameters necessary for use with the statement, function, command or object. Describes the purpose of the statement, function, command or object. Lists specific considerations for the statement, function, command or object. Actual script example illustrating the use of the statement, function, command or object. Direct links to related statements, topics, functions, commands or objects.
E-Prime User’s Guide Chapter 4: Using E-Basic Thus, when the experiment is executed, a specific exemplar is selected from the TrialList object. An examplar from a List is an entire row (or level). In the current example, a chosen exemplar includes the data to present the stimulus (Stimulus = either X or Y) and score the response (CorrectAnswer = 1 or 2), as well as the Procedure using that data (TrialProc).
E-Prime User’s Guide Chapter 4: Using E-Basic For example, if an attribute is defined at the block level, this attribute will be available at the block level and all levels subordinate to the block level (e.g., trial, sub-trial, etc.). When values are requested, the current level is searched first, and the search continues upward through the levels until a value is found or until all levels have been exhausted. This defines a hierarchy of context levels within the overall Context.
E-Prime User’s Guide Chapter 4: Using E-Basic 4.3.3.1 Commands Commands are used to instruct the program to perform an operation. For example, the Run command is used to launch the object named "Stimulus" within the experiment script. Stimulus.Run Commands may or may not take parameters. A listing of all commands associated with particular objects is available in the E-Basic Online Help. 4.3.3.2 Functions Like commands, functions are used to instruct the program to perform an operation.
E-Prime User’s Guide Chapter 4: Using E-Basic Rules • • • • • • • • • Must begin with a letter. Numbers are acceptable but may not appear in the first character position. 1 Punctuation is not permitted, with the exception of the underscore character and the exclamation point (see above paragraph for details). Illegal characters include: @#$%^&*(){}-+[]=><~`:; Spaces are not permitted. Maximum number of characters is 80. Cannot duplicate a reserved word.
E-Prime User’s Guide Chapter 4: Using E-Basic 4.4 Basic Steps for Writing E-Prime Script The following steps, to be covered in this section, introduce helpful information for writing E-Basic script or accessing values determined through script. 1. 2. 3. 4. 5. 6. 7.
E-Prime User’s Guide Chapter 4: Using E-Basic After placing an InLine object in the appropriate location, double click the InLine object to open it, and enter the script required to accomplish the task. To select a random number (1-499), and to place the selected value into a form useable by E-Prime, the following script would be entered: The Random function is used to select a random value from 1-499, and the SetAttrib command is used to place that value into an attribute for later access.
E-Prime User’s Guide Chapter 4: Using E-Basic Initialization of global variables cannot occur on the User tab; instead, an InLine object would be used for this purpose. To initialize a global variable prior to its use (e.g., to initialize the number of trials to 0), use an InLine object placed appropriately. It is a good practice to initialize variables as the first event in the Procedure in which they will be used as part of the Procedure setup events.
E-Prime User’s Guide Chapter 4: Using E-Basic The total trial count variable is updated simply by increasing the previous value by one (i.e., g_nTotalTrial+1). The second line of script referring to the c.SetAttrib command is used to place the value of g_nTotalTrial into an attribute for access by another object and to log the value in the data file. Refer to the next step for information pertaining to setting values as attributes. 4.4.
E-Prime User’s Guide Chapter 4: Using E-Basic Note the use of the "Else" condition in the script above. It is a good practice, and ultimately the programmer’s responsibility, to cover all possibilities when writing script. If the values of the Condition attribute are carefully entered, the "Else" condition should not be necessary. However, it is better to consider the possibility of error than to have the program fail.
E-Prime User’s Guide Chapter 4: Using E-Basic the random value has been set as an attribute at the beginning of the trial Procedure, that attribute may be referenced by a TextDisplay object in order to display the value as the stimulus during the trial. To refer to an attribute, use square brackets surrounding the attribute name (e.g., [Stim]) in the Text field of the TextDisplay object. Note most properties may be changed through script as well.
E-Prime User’s Guide Chapter 4: Using E-Basic Debug.Print may also be used to monitor timing and response events. The following script uses Debug.Print to write the stimulus onset time and the subject’s response to the Output window. The contents of the Debug tab may be copied to the clipboard by right clicking in the Output window. Then, the Debug output may be pasted into Excel to print it or use spreadsheet calculations to check the timing of events.
E-Prime User’s Guide Chapter 4: Using E-Basic 4.4.7 Test After the experiment is functioning without errors, it is important to completely test it prior to running subjects. The Debug object is especially useful for testing an experiment. Use the Debug.Print command to send variable values to the Output window, and keep track of the progress of the experiment with a pencil and paper as well. After running the experiment, examine the output on the Debug tab to view the values.
E-Prime User’s Guide Chapter 4: Using E-Basic If…Then statements simply are equated to making a choice (e.g., if I have money, then I can go to the movies). If…Then statements are the foundation of all logic. Although they seem to be very simple statements, they are quite powerful in a programming language. There are actually 3 conditional expressions available in E-Basic. They are: If…Then, Select Case, and Do…Loop.
E-Prime User’s Guide Chapter 4: Using E-Basic If…Then…Else statements If the program must choose between two alternative blocks of code to execute based on the conditional, then the Else statement is included. Dim a As Integer a = 12 If a > 10 Then MsgBox "A is greater than 10." Else MsgBox "A is not greater than 10." End If Select Case statements Nested If…Then statements are ideal for testing different values before executing the next block of code.
E-Prime User’s Guide Chapter 4: Using E-Basic Do…Loops There are a variety of Do …Loops available in E-Basic. Statement Description Do…Loop Repeats the block of code until a condition is true and then executes an End Do statement. Repeats the block of code only while a condition is true. Executes the block of code once and then repeats it until the condition is false. Executes and repeats the block of code only while the condition is false.
E-Prime User’s Guide Chapter 4: Using E-Basic Do…Loop Until Like the Do While Loop varieties, the Do Until Loop also offers the option of setting when the condition is evaluated. In this case, the condition is evaluated at the end of the block of code. Therefore, the block of code is executed at least once. Do Loop Until condition Do Loops with If..
E-Prime User’s Guide Chapter 4: Using E-Basic When the loop begins, the counter is set to start. When the Next statement is executed, the counter is incremented by one. When the counter is equal to the end value supplied, the loop terminates and the next line of code outside the loop structure is executed. Tips: • Keep it simple. Unless there is a specific reason to start the counter at another value, use 1 to n.
E-Prime User’s Guide Chapter 4: Using E-Basic to perform the response collection again. If the required input is entered (i.e., "a"), the program jumps to a point later in the script. Dim answer As String LabelB: answer = AskBox ("Type in a letter:") If answer = "a" Then Goto LabelA Else MsgBox "That is the wrong letter, try again!" Goto LabelB 'Ask for another letter End If LabelA: MsgBox "Way to go!" 4.5.
E-Prime User’s Guide Chapter 4: Using E-Basic 'Set TotalTrial=10 c.SetAttrib "TotalTrial,” 10 Once an attribute is put into the context, the information is logged in the data file and the attribute may be used to display information by way of a display object (e.g., a TextDisplay). The TotalTrial attribute will be available in the context during the scope of the level at which it has been defined.
E-Prime User’s Guide Chapter 4: Using E-Basic The inheritance of the value to assign to an attribute follows the hierarchical structure, and values may only be inherited by levels lower than the level at which the attribute is defined. Thus, if an attribute is defined at the block level, it may be referenced at the trial or sub-trial level. Inheritance occurs in a downward direction, while the search for a value occurs in an upward direction.
E-Prime User’s Guide Chapter 4: Using E-Basic Once declared in the User Script window, the variables are available globally, or for the scope of the entire experiment. The variables must be initialized prior to the point in the experiment at which they are referenced. This would be accomplished using an InLine object, inserted on the Session Procedure timeline.
E-Prime User’s Guide Chapter 4: Using E-Basic 'Collect response from AskBox Dim strAnswer As String strAnswer = AskBox ("Type in the recalled word:") RecallStim.RESP = strAnswer RecallStim.CRESP = c.GetAttrib("CorrectAnswer") 4.5.3.6 Example 6: Using Attribute References to Pass Information Attributes allow the passing of variable information during a Procedure. For example, in order to vary the stimulus presented per trial, the stimulus values (e.g.
E-Prime User’s Guide Chapter 4: Using E-Basic 4.5.4 Additional Information For more details concerning E-Basic, refer to Chapter 2-E-Basic in the E-Prime Reference Guide. The complete E-Basic scripting language is fully documented in the E-Basic Online Help. This is accessible via the E-Studio Help menu, or in the E-Prime menu. 4.6 Programming: Intermediate 4.6.1 More on Variables There is much more information pertaining to variables that should be learned.
E-Prime User’s Guide Chapter 4: Using E-Basic necessary to convert information from one type to another in order to store it in a particular variable. E-Basic contains several functions for the purpose of conversion between data types. Function Description CCur Converts any expression to a Currency. CBool Converts expression to True or False, returning a Boolean value. CDate, CVDate Converts expression to a date, returning a Date value. CDbl Converts any expression to a Double.
E-Prime User’s Guide Chapter 4: Using E-Basic Dim stringVal As String stringVal = "This is the value of the string." If the expression extends past a single line, the expression statement must be divided into separate strings, which are concatenated. The ampersand (&) is used for this purpose. No linefeeds or carriage returns are included in the concatenation of strings, unless the new line (\n) character is included.
E-Prime User’s Guide Chapter 4: Using E-Basic 'Subroutine containing the script necessary to set the 'background to red. Dim cnvs As Canvas Sub ClearToRed cnvs.FillColor = CColor("Red") cnvs.Clear End Sub In the example below, the ClearToRed subroutine is called to quickly set the background to red before 10 circles are drawn on the Canvas. The script below would be placed in an InLine object called during the experiment. 'Clear the screen to red and draw 10 circles of random 'size.
E-Prime User’s Guide Chapter 4: Using E-Basic Thus entered in the User Script window, the DoMean function may be used at any time during the experiment. The CalcMean InLine object below calls the DoMean Function to calculate the mean of 5 randomly chosen numbers.
E-Prime User’s Guide Chapter 4: Using E-Basic Dim position_array ( ) As Integer Fixed arrays The dimensions of fixed arrays cannot be adjusted at execution time. Once declared, a fixed array will always require the same amount of storage. Fixed arrays can be declared with the Dim statement by supplying explicit dimensions.
E-Prime User’s Guide Chapter 4: Using E-Basic Addressing an element within an array The individual elements within an array may be accessed or set simply by listing the array name, and using subscript notation (i.e., the index number enclosed in parentheses) to refer to the appropriate index. The index of the array includes an integer value for each dimension of the array.
E-Prime User’s Guide Chapter 4: Using E-Basic 4.7.2 Timing Refer to Chapter 3-Critical Timing in the User’s Guide for a detailed discussion of critical timing issues and techniques. 4.7.3 User-Defined Data Types E-Basic allows the user to define data types. User-defined data types are very useful for organizing related data items of various types. A user-defined data type is declared using the Type statement, and the data items organized by the data type are listed in the Type statement.
E-Prime User’s Guide Chapter 4: Using E-Basic 'If the subject enters "1" run Procedure 1, otherwise run 'Procedure 2. If subject.RESP = "1" Then List1.Run Else List2.Run End If 4.7.4.2 Arrays Creating a single dimension array, assigning values, and accessing values for display.
E-Prime User’s Guide Chapter 4: Using E-Basic 4.7.5 Additional Information For further details concerning E-Basic, refer to Chapter 2-E-Basic in the E-Prime Reference Guide and the E-Basic Online Help. The complete E-Basic scripting language is fully documented in Online Help. This is accessible via the E-Studio Help menu, or through the EPrime menu via the Start button. 4.8 Debugging in E-Prime Errors may occur during both the generation and the running of an experiment.
E-Prime User’s Guide Chapter 4: Using E-Basic The errors will also be sent to the Debug tab in the Output window. After dismissing the error dialog, the errors may be redisplayed by opening the Output window (View menu) and clicking the Debug tab. Each error will display the line number in the script at which the error occurred, and the Script window will open automatically in E-Studio to display the full experiment script.
E-Prime User’s Guide Chapter 4: Using E-Basic 4.8.1 Tips to help make debugging easier Ø Run in fixed order to verify proper stimulus selection before adding randomization. Ø Think small -- test small portions of the program for functionality before expanding the program. Ø Use Debug.Print to send information to the Output window during runtime. This information may be evaluated after the run terminates in order to verify values. Ø In an Inline object, use Display.Canvas.
E-Prime User’s Guide Chapter 5: Data Handling Chapter 5: Data Handling 5.1 Overview of Data Handling With E-Merge and E-DataAid, E-Prime provides tools to support data management and analysis. The E-Merge application merges individual data files into aggregate data files for group analysis. The E-DataAid application enables experimenters to view and edit data, generate descriptive statistics and plots of the results, and export the data and analysis results to other applications.
E-Prime User’s Guide Chapter 5: Data Handling Figure 1. Single folder organization. Figure 2. Subfolder organization, organizing data files for subjects receiving different conditions. 5.2.3 Merge E-Merge offers two merge operation options: Standard and Recursive. The Standard merge operation (demonstrated in the Getting Started Guide) merges data files from a single folder into a target file. This is the most common type of merge operation.
E-Prime User’s Guide Chapter 5: Data Handling Select Files Once the data files within a folder are displayed, select the specific data files to merge. To select all data files that have never been merged, click the Select Unmerged tool button in the toolbar. To select all files, use the Select All command from the Edit menu. The Select All command selects all E-Prime data files (EDAT and EMRG) regardless of their merge status (i.e., never merged or previously merged).
E-Prime User’s Guide Chapter 5: Data Handling are in ascending order. Because the file names are sorted based on string order, a file name with subject 10 in it may appear before a file name with subject 2 in it. Click Merge Button Once the files are selected in the File List, click the Merge button to begin the merge operation. The Select the Merge Operation dialog appears, prompting the user to select the type of merge operation to perform. The default setting is the Standard merge operation.
E-Prime User’s Guide Chapter 5: Data Handling After completing the merge operation, the application will display the Merge Results dialog, summarizing the operation. In addition, the details concerning the success or failure of merging specific files is reflected in the Merge Log view. The status of a particular file (e.g., previously merged to a target file, set as the target file, never been merged, etc.) may be observed by viewing a file’s icon in the File List view.
E-Prime User’s Guide Chapter 5: Data Handling folder are exact copies of the files in the Data folder (i.e., they are backup files for working with the E-Prime Getting Started Guide). However, these files will sufficiently illustrate the Recursive merge procedure. Click Merge Button Once the parent data folder (i.e., Data) is selected in the Folder Tree, click the Merge button to begin the merge operation.
E-Prime User’s Guide Chapter 5: Data Handling files, EMRG files, or all E-Prime data files) and a merge status (never merged, already merged, or ignore merge status). Accept the default settings, and click the Next button to include all EDAT files that have not previously been merged. The merge operation will then continue as it does in the Standard merge (i.e., by prompting for the target file).
E-Prime User’s Guide Chapter 5: Data Handling As with the standard merge operation, the Merge Log and the File List contain feedback about the merge operation. Selecting the Data folder and the Originals folder independently, in the Folder Tree, will reveal the individual data files that have been merged during the operation. Notice that the data files from the Originals folder were actually merged into a target file in a different folder location (i.e., Data folder). Figure 1.
E-Prime User’s Guide Chapter 5: Data Handling When a merge operation is undone, the files and icons return to the status maintained prior to the merge operation. For example, if an unmerged file is included in a merge operation, the file would then be classified as “already merged,” and the icon for that file would receive a green checkmark. If the merge operation is subsequently undone, the file status would return to “unmerged,” and the green checkmark would be removed from the icon.
E-Prime User’s Guide Chapter 5: Data Handling A violation of the second rule is even more rare because E-Run logs all variables, with the exception of subject and session number, as string data. This situation would occur only if a variable of an integer or float data type was created in the data file using E-DataAid and then the user attempted to merge the data file into a target file that already had a string variable with the same name.
E-Prime User’s Guide Chapter 5: Data Handling To successfully merge the source file into the target file, the variable or log-level causing the conflict must be renamed before attempting the merge operation again. 5.2.4.2 Duplicate Data Versus Different Runs Another potential conflict involves duplicate data in a merged data file (i.e., merging the same data more than once into the same file).
E-Prime User’s Guide Chapter 5: Data Handling If the user chooses option #2 (to merge the data containing the duplicate subject and session number), the target file should be edited immediately using E-DataAid in order to avoid potential confusion. E-Merge determines whether data is duplicate data or a different run based on a unique identifier assigned to the data by E-Run.
E-Prime User’s Guide Chapter 5: Data Handling 5.2.5 Review Merge History For single EDAT files, the file names convey information about the contents of the data files, as do the Experiment, Subject, and Session columns in the File List view. However, as illustrated in the image below, the contents of an EMRG file cannot be determined simply by looking at the name of the file or the File List view. One way to determine the contents of an EMRG file is to open it in E-DataAid.
E-Prime User’s Guide Chapter 5: Data Handling To view the files that have been merged into the file, select the Merge Input History tab (Figure 1). This page list all of the files merged into the selected file in the order in which they were merged. To see the entire file name, simply rest the cursor on the name. To view the sessions that a file contained when it was merged, select the file in the list and click the details button.
E-Prime User’s Guide Chapter 5: Data Handling 5.3 Data Handling Using E-DataAid 5.3.1 Introduction E-DataAid is E-Prime’s data editing and analysis application. Single E-Prime EDAT files generated by E-Run or merged E-Prime EMRG files generated by E-Merge may be opened for viewing, editing, and analysis with E-DataAid.
E-Prime User’s Guide Chapter 5: Data Handling each level of the experiment, E-Run logs many other variables for each List and Procedure object used in the experiment. This is by design, and is an important feature for verifying the correctness of the experiment’s structure. However, during the data-handling phase, these “extra” variables may lose their usefulness, and even hamper the user’s ability to view the data.
E-Prime User’s Guide Chapter 5: Data Handling Select the Block level in this dialog and click the OK button to collapse the spreadsheet at the Block level. This will display only the unique occurrences at this level and all higher levels (i.e., Session level). Lower levels are hidden from view. The image below illustrates the MergedData.emrg file, obtained from section 5.2.3.1 in this chapter, collapsed at the Block level.
E-Prime User’s Guide Chapter 5: Data Handling Figure 1. Columns to be removed are selected. Figure 2. The selected columns are moved to the “Hide these columns” side of the dialog by clicking the Remove button. When the OK button is clicked, the columns in the left list will be removed from the display. The columns to be displayed may be reordered by using the Move Up or Move Down buttons below the list.
E-Prime User’s Guide Chapter 5: Data Handling 5.3.2.3 Filter Rows Most likely, there will be data that the user does not want to include in the spreadsheet. For example, it may not be desirable to view or analyze practice data, incorrect trials, or response times outside of a specific range (e.g., RT < 100). E-DataAid offers the ability to filter the data based on specific criteria using the Filter command. When filtered, the spreadsheet will display only data matching the filter criterion.
E-Prime User’s Guide Chapter 5: Data Handling Range Filter The Range filter permits the user to create expressions that define the range of values to include in the spreadsheet. For example, the user may want to filter the spreadsheet so that only response times between 400 and 1000 milliseconds are displayed. To apply such a filter, select the variable containing the RT data (e.g., Target.RT) in the Column name list and click the Range button.
E-Prime User’s Guide Chapter 5: Data Handling Visual Cues The spreadsheet provides a number of visual cues to remind the user that filters have been applied to the displayed data. First, filtered columns have white column headers rather than gray, and rows are numbered non-consecutively. Below the spreadsheet, the Filter Bar, labeled “Filters,” displays the current filters. At the bottom of the display, the Status Bar displays the number of unhidden rows.
E-Prime User’s Guide Chapter 5: Data Handling 5.3.2.4 Restore the Spreadsheet It is not uncommon to need to restore the spreadsheet to its default format (i.e., the data file’s format when it is opened for the first time in E-DataAid). When a data file is opened, it will open in the format in which it was saved, with the exception of filters (filters are not saved when the file is closed). The default format is equal to collapsing the spreadsheet at the lowest level (i.e., all data is displayed).
E-Prime User’s Guide Chapter 5: Data Handling After the data file has been saved and closed, the edited data will continue to appear in red. If the user chooses to “undo” the edit before closing the file, the data will revert to the original black color. Thus, upon opening a file, it is possible to immediately determine if any data has been edited. 5.3.3.2 Annotations For each modification made to a data file, E-DataAid writes an annotation, which is saved with the file.
E-Prime User’s Guide Chapter 5: Data Handling 5.3.3.3 Comments E-DataAid allows the user to add comments to the data file. For example, it may be beneficial to add comments concerning a specific subject, the procedure, something that may have influenced the session, etc. To add a comment to the file, first use E-DataAid’s Display Annotations command on the View menu to display the Annotations dialog. Click the Create New button to display the Annotation Text dialog.
E-Prime User’s Guide Chapter 5: Data Handling the experiment Administrator has placed security restrictions on the file and has set the cells as read-only. Like other popular spreadsheet applications, E-DataAid provides common commands, such as Find, Replace, Fill Down, Copy, and Paste, to make the chore of editing many cells easier. Since these commands are not unique to E-DataAid, time is not spent describing them here.
E-Prime User’s Guide Chapter 5: Data Handling Enter the variable’s new name. The new name must begin with a letter, must be composed of only letters, numbers, periods, or underscores, must not exceed 80 characters, and must not already be in use. After entering the new name, click the OK button to rename the variable. With the exception of log-level names, the variable’s new name is considered an edit.
E-Prime User’s Guide Chapter 5: Data Handling E-DataAid’s Undo command only reverses actions related to edits. The undo command does not act like a “general undo” to reverse other actions as in other applications, such as hiding or resizing columns. To undo an edit, click the Undo button, or use the Undo command in the Edit menu. 5.3.5 Analysis The Analyze command within E-DataAid allows the creation of tables and graphs of the data.
E-Prime User’s Guide Chapter 5: Data Handling NameGender to the Columns list, drag Target.RT to the Data list, and drag Subject to the Rows list (Figure 1). Once defined, click the Run button to perform the analysis. Figure 1. Analyze dialog allows selection of variables for analysis. Figure 2. Table created from analysis specifications. The settings for the current analysis may be cleared by clicking the New button on the Analyze dialog.
E-Prime User’s Guide Chapter 5: Data Handling a statistic is chosen, the variable displays the statistic after its name in the Data field of the Analyze dialog. To calculate more than one statistic for the same variable, add that variable to the Data list more than once. For example, to calculate the count, mean, and standard deviation for a variable, drag and drop the variable from the Variable’s list to the Data list three times.
E-Prime User’s Guide Chapter 5: Data Handling The resulting table will contain bins of data of the specified size for that variable. For example, to count the number of correct responses occurring during the Tutorial experiment at various levels of the range of reaction times, the experimenter would place the Target.RT variable in the Rows list and the Target.ACC variable in the Data list, set a filter to include only correct responses (ACC = 1), double click the Target.
E-Prime User’s Guide Chapter 5: Data Handling the experimenter provided a name for the analysis, the name will appear in the Save As dialog; otherwise, a name must be entered. Analyses are saved in text file format with the ANL extension. These text files can be read by EDataAid using the Load Analysis button on the Analyze dialog. When E-DataAid saves an analysis, it saves the configuration for the analysis, the spreadsheet’s filters, the table’s options, and the plot options if applicable.
E-Prime User’s Guide Chapter 5: Data Handling 5.3.5.7 Example Analyses Many different analyses are permitted by the Analyze command. Some examples are provided below. Table of Means The following analysis creates a table of means excluding practice trials and including only correct answers.
E-Prime User’s Guide Chapter 5: Data Handling Proportion Correct by Subject The following analysis creates a table of the proportion correct by subject excluding practice trials. Distribution of RT The following analysis creates a distribution of response times in bins of 100 milliseconds excluding practice trials and including only correct answers.
E-Prime User’s Guide Chapter 5: Data Handling Multiple Stats by Condition The following analysis creates a table of count, mean, and standard deviation by conditions for real trials with correct answers only. One Line Per Subject The following analysis creates a table of all response times on one line per subject for real trials only.
E-Prime User’s Guide Chapter 5: Data Handling 5.3.6 Use the Results Once a table has been created, it may be copied to the clipboard, exported to a text file for further analysis in another application, or plotted. E-DataAid allows the user to easily format a table, copy it, export it, and even plot it to Excel (Excel97 or Excel2000 must be installed on the working machine for this option). 5.3.6.1 Format the Table By default, when an analysis is run, the resulting table follows a default format.
E-Prime User’s Guide Chapter 5: Data Handling Excel Copy If Excel97 or Excel2000 is installed on the machine, the table may be copied directly to Excel by clicking the Excel Copy button on the Table dialog. If a workbook is currently open in Excel, EDataAid will add a new worksheet to the workbook and copy the table to it. If Excel is not open, E-DataAid will open Excel and create a new workbook before performing the copy. The image below displays a table copied from E-DataAid to Excel. 5.3.6.
E-Prime User’s Guide Chapter 5: Data Handling Once correctly formatted, the table may be plotted by clicking the Excel Copy button. If a workbook is currently open in Excel, E-DataAid will add a new worksheet to the workbook and plot the table to it. In addition to the plot, the application also copies the table to the worksheet. If Excel is not open, E-DataAid will open it and create a new workbook before performing the plot. The picture below displays a table automatically plotted in Excel.
E-Prime User’s Guide Chapter 5: Data Handling Select the plot type (column or line) as well as the plot orientation (column or row). A column orientation means that the application plots the data series by columns. In other words, the column labels make up the plot’s legend and the row labels make up the x-axis labels. A row orientation means that the application plots the data series by rows. In other words, the row labels make up the plot’s legend and the column labels make up the x-axis labels.
E-Prime User’s Guide Chapter 5: Data Handling Figure 3. Line plot with column orientation. Figure 4. Line plot with row orientation. On the Plot Options dialog, the y-axis scale, chart title, and/or y-axis title may be set by unchecking the respective box labeled “Auto” and entering values into the adjacent fields. Note, once the plot has been exported to Excel, settings may be altered using the plot options in Excel. 5.3.
E-Prime User’s Guide Chapter 5: Data Handling In the first field, type the current password (i.e., “admin,” if not previously changed). The password will appear as asterisks when typed. In the second field, type the new password. Passwords are not case-sensitive and must be 4 to 8 alphanumeric characters. In the third field, type the new password again for verification. Click the OK button to change the password. E-DataAid’s password is machine dependent.
E-Prime User’s Guide Chapter 5: Data Handling Most often the Administrator will simply want to either make the file read-only or clear any security restrictions from the file. To make the file read-only, click the Disallow All Edits button on the Security dialog. Similarly, to clear all security restrictions, click the Clear All Security button on the Security dialog. Click the OK button to apply or remove the security. Save the data file.
E-Prime User’s Guide Chapter 5: Data Handling Administrator chooses the “Hide data” option for a variable, when the data file is opened with the Open command, the spreadsheet will display a column for that variable but the cells in that column will be blank. Likewise, the “Disallow edits” setting applied to a variable will result in a display containing a column for that variable with data in the cells, but the cells will be read-only. Similar security settings may be applied to annotations. 5.3.
E-Prime User’s Guide References References Busey, T.A., & Loftus, G. R. (1994). Sensory and cognitive components of visual information acquisition. Psychology Review, 10, 446-449. Chow, S. L. (1998). Précis of Statistical significance: Rationale, validity and utility. Behavioral and Brain Sciences, 21, 169-239. Chute, Douglas L., (1986). MacLaboratory for psychology: General experimental psychology with Apple’s Macintosh. Behavior Research Methods, Instruments and Computers, 18(2), 205209.
E-Prime User’s Guide References Schneider, W. Zuccolotto, A. & Tirone, S.T. (1993). Time-stamping computer events to report .1 msec accuracy of events in the Micro Experimental Laboratory. Behavior, Research Methods, Instruments, & Computers, 25, 276-280. Segalowtz, S. J., & Graves, R.E. (1990). Suitability of the IBM, XT, AT and PS/2 keyboard, mouse, and game port as response devices in reaction time paradigms. Behavior Research Methods, Instruments, & Computers, 22, 283-289. Ulrich, R. & Miller, J.
E-Prime User’s Guide Appendix A: Timing Test Results Appendix A: Timing Test Results Windows desktop computers can support millisecond precision timing if they are reasonably configured. It is prudent to run the time test programs whenever new hardware or applications are added to the computer. The timing test results in this section show that E-Prime can maintain millisecond precision on appropriately tuned desktop PC hardware for Pentium class machines running at 120MHz or faster.
E-Prime User’s Guide Appendix A: Timing Test Results computer. Figure 1 is a display of a completely clean computer. This is the ideal scenario and may not be possible to achieve on all hardware setups because of various drivers that may be required for proper operation of the computer hardware. The Windows Explorer application will always be listed, as it is responsible for running the Windows desktop.
E-Prime User’s Guide Appendix A: Timing Test Results Figure 2. E-Prime Refresh Clock Test display after 50 runs. The E-Prime Refresh Clock Test program provides a good diagnostic of a computer’s suitability for data collection, and assesses several critical characteristics about the computer. The most important test is the Clock Test. The Clock Test monitors the clock for a period of 10000 milliseconds and checks to see if continuous readings of the clock ever failed to identify sequential clock ticks.
E-Prime User’s Guide Appendix A: Timing Test Results 19 code and less than 50% with using the vertical blank simulation code . This allows the software to resynchronize, on average, once every 2 refreshes. However, this might cause the top 10% of the display to not be updated on a missed refresh event. For experiments in which you are altering the very top of the screen on single refreshes, the rate of missed refreshes should be less than 0.1%.
E-Prime User’s Guide Appendix A: Timing Test Results Meaning of Individual Results Results block Test ID 1% Rule Ms Rule Test number in the series. Letters indicate multiples of 10. The number of extra trials necessary in order to compensate for the timing errors that occurred from a less than perfect machine. Results from the clock testing runs as shown in Figure 2, indicating whether a greater than ½millisecond error occurred.
E-Prime User’s Guide Appendix A: Timing Test Results Having a well-configured machine is critical for achieving accurate timing during the run of an experiment. Figure 4 illustrates the importance of the configuration of the hardware and how dramatically it can impact millisecond precision. Missed Clock Ticks 1000 900 Milliseconds Lost 800 700 600 With network connected 500 Without network connected 400 300 200 100 0 0 10 20 30 40 50 Sequential Run Figure 4.
E-Prime User’s Guide Appendix A: Timing Test Results Percentage of Missed Ticks by Block 0.025 % Missed Ticks 0.02 0.015 0.01 0.005 0 1 101 201 301 401 501 601 701 801 901 801 901 Sequential Run 1-1000 Figure 5a. A good missed tick pattern across time. Percentage of Missed Ticks by Block 30 % Missed Ticks 25 20 15 10 5 0 1 101 201 301 401 501 601 701 Sequential Run 1-1000 Figure 5b. A stable missed tick pattern across time.
E-Prime User’s Guide Appendix A: Timing Test Results Percentage of Missed Ticks by Block % Missed Ticks 5 4 3 2 1 0 1 101 201 301 401 501 601 701 801 901 Sequential Run 1-1000 Figure 5c. A large rhythmic time loss pattern. Included with the RefeshClockTest program are E-DataAid Analysis forms for the following analyses: TicksMissedPercent.ANL Shows the missed tick percentage by test run. This value should be below 0.1%.
E-Prime User’s Guide Appendix A: Timing Test Results Analyze the timing test results for long-term stability using E-DataAid (see Getting Started GuideTutorial 4: E-DataAid). To examine the data in E-DataAid follow the steps listed below: 1. Open E-DataAid via the Start menu and load in the data file (e.g., RefreshClockTest-11.EDAT). 2. From the Tools menu, select the Analyze option. 3. In the Analyze dialog, click the Load Analysis button and select the analysis file (testname.anl). 4.
E-Prime User’s Guide Appendix A: Timing Test Results Percentage of Missed Ticks by Block 0.045 % Missed Ticks 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0 Sequential Run 1-1000 Figure 6. Percentage of millisecond ticks missed as a function of the test run. This should be less than 0.1% (TicksMissedPercent.ANL). The graph of the Maximum Missed Tick measure (Figure 7) provides an estimate of the worstcase delay in the running of an experiment.
E-Prime User’s Guide Appendix A: Timing Test Results interrupts (in the range of 7-9ms) per 10 seconds. This program would have to be shut down if millisecond precision is required. Mean Count by Delay 4500 4000 Delay (ms) 3500 3000 2500 2000 1500 1000 500 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Mean Count Figure 8. Distribution of tick times from a laptop computer, showing frequent 8ms duration interrupts (BinCount.ANL).
E-Prime User’s Guide Appendix A: Timing Test Results Tests were conducted on a wide range of machine configurations. Sample results provided in this text are from a representative ‘low-to-mid-range’ class machine* with the following specific configuration.
E-Prime User’s Guide Appendix A: Timing Test Results Test Equipment Details Timer Circuitry The clock and counter circuitry of the BSOFT DIG-130 digital I/O card consists of three 16-bit counters (C0, C1, C2) supported by a D71054C-10 (8254) IC driver with a 10.000MHz oscillator. The 16-bit counters can be programmed for counting, generating square waves, or providing precise interrupt timing functions.
E-Prime User’s Guide Appendix A: Timing Test Results Microsoft 2 Button PS/2 Mouse (modified for use) –the Microsoft mouse was modified on the left switch to parallel in a high-speed reed relay (see #3 above). An external o-scope probe was wired to the opposite side of the relay so that the TS could verify and timestamp when the mouse switch device was activated (i.e., when the switch was actually closed).
E-Prime User’s Guide Appendix A: Timing Test Results ABSOLUTE TIMING ERROR BY VARYING INTERVAL Varying Interval (ms) Average of ABS ERROR StdDev of ABS ERROR Min of ABS ERROR Max of ABS ERROR +1 0.174 0.204 0.026 1.514 +2 0.166 0.167 0.051 1.492 +3 0.155 0.159 0.032 1.230 PRIMES 0.121 0.023 0.057 0.164 Grand Total 0.162 0.171 0.026 1.514 N (Num of Intervals) 100 100 100 25 325 2c.
E-Prime User’s Guide Appendix A: Timing Test Results ACTUAL KEYBOARD RESPONSE DELAY BY VARYING INTERVAL (SINGLE FRAME) Varying Interval (ms) +1 +2 +3 PRIMES Grand Total Average of ACTUAL DELAY StdDev of ACTUAL DELAY Min of ACTUAL DELAY Max of ACTUAL DELAY 6.311 0.714 4.806 7.813 6.483 0.835 4.802 7.816 6.686 0.715 5.800 7.816 5.921 0.816 4.806 7.627 6.450 0.787 4.802 7.
E-Prime User’s Guide Appendix A: Timing Test Results ACTUAL MOUSE RESPONSE DELAY BY VARYING INTERVAL (SINGLE FRAME) Varying Interval (ms) +1 PRIMES Grand Total Average of ACTUAL DELAY StdDev of ACTUAL DELAY Min of ACTUAL DELAY Max of ACTUAL DELAY 96.006 7.360 83.805 107.814 98.002 5.816 83.809 105.813 96.405 7.102 83.805 107.
E-Prime User’s Guide Appendix A: Timing Test Results 4. Audio Output Latency – This test checks the delay between when an audio output is initiated to the time until a signal is detected at the output of the audio card. During this test an audio signal detector circuit is plugged into the output jack of the audio card. When an audio signal is detected, a pulse is generated on a TTL line connected to the TS.
E-Prime User’s Guide Appendix B: Considerations in Research Appendix B: Considerations in Computerized Research -- Contributed by James St. James, Millikin University While many of the persons using E-Prime are intimately familiar with the intricacies of research, many are not, or are just beginning to learn. In this chapter, we present a brief overview of experimental research, including review of some basic terms and ideas.
E-Prime User’s Guide Appendix B: Considerations in Research the experiment that will be manipulated. The independent variables may be manipulated by randomly assigning subjects to conditions (levels of the IV), or by applying each condition to each subject, in a random or counterbalanced order. In discussing statistical analysis of experiments, independent variables are also sometimes called factors. An experiment with more than one IV is said to use a factorial design.
E-Prime User’s Guide Appendix B: Considerations in Research subjects required. In this case, a Latin square design can approximate complete counterbalancing.) An alternative is to randomize the order of presentation of the experimental conditions for each subject. Over a fairly large number of subjects, this will approximate counterbalancing.
E-Prime User’s Guide Appendix B: Considerations in Research prediction about how the DV will change, but there is the expectation that changes in the IV’s studied will produce changes in the DV. If they do not, not much exploration has taken place. How will data be analyzed? The experiment and the data analysis should be co-designed. It is extremely important that the methods of data analysis be known in advance of collecting the data. There are several reasons why this is so.
E-Prime User’s Guide Appendix B: Considerations in Research Thorough testing with a few trials of each type will usually catch such errors while they are easy to correct. As an example, suppose that you have to type in 200 words to serve as stimuli, and designate each word by frequency and length. If you then decided to add concreteness as an additional IV, you must enter the concreteness rating for each of the 200 words.
E-Prime User’s Guide Appendix B: Considerations in Research Familiarizing subjects with the situation Especially with computerized experiments, it is sometimes necessary to spend time making sure subjects are comfortable, because they need to do the experimental task without being distracted by the surroundings. Many researchers rely on undergraduates as subjects, and can assume a familiarity with computers. However, in an elderly population, the subjects may not be familiar with computers.
E-Prime User’s Guide Appendix B: Considerations in Research Is a keyboard the right input device? Typically, keyboards are used for response collection, usually limiting the allowable keys to those used for responses. However, in many situations, a keyboard may cause problems. Subjects can easily be confused about which keys are being used. If working in a darkened room, locating the right keys can be difficult.
E-Prime User’s Guide Appendix B: Considerations in Research While we have defined RT as the time from stimulus onset to a response, it is sometimes defined in other ways. In much research in kinesiology, for example, RT is defined in relation to the onset of a muscle potential (electromyographic signal), while the time from that first electrical activity in the muscle to when the response movement itself is completed is called Motor Time.
E-Prime User’s Guide Appendix B: Considerations in Research At the end of the foreperiod, the stimulus is presented. In many experiments there is only a single event making up the overall stimulus. In others, there may be distracter elements displayed on the screen, or stimuli that serve as primes. In either event, timing of the reaction begins when the critical stimulus is displayed. The critical stimulus refers to the element in the display that determines the appropriate reaction (i.e.
E-Prime User’s Guide Appendix B: Considerations in Research and thus not be looking at the fixation when the trials begin. This can be prevented by stressing in the instructions that subjects should be looking directly at the fixation when they start each trial, and also by randomly presenting the stimuli to left or right of fixation. If subjects adopt a guessing strategy, this will lead to them missing many stimuli completely, and the high error rates will clearly show that there is a problem.
E-Prime User’s Guide Appendix B: Considerations in Research When blocked presentation is used, the issue of counterbalancing of treatment orders is raised. In the blocked version of the two- versus four-response experiment (two levels of one independent variable), half of the subjects would do the two-choice trials first, while half would do the four-choice trials first. This counterbalancing is designed to remove (or at least balance) any effects of carry-over from one block of trials to the next.
E-Prime User’s Guide Appendix B: Considerations in Research experiment and to permit questions about it. Instructions, practice, and debriefing are considered separately below. Instructions The purpose of the instructions, in any experiment, is to let the subject know what will be happening and what the correct responses are. In RT research, instructions should also emphasize that subjects are to respond as quickly as possible while still remaining accurate.
E-Prime User’s Guide Appendix B: Considerations in Research How many trials? Why not just have the subject respond once to each type of display, and take that single RT as the "score" for that condition? This would certainly be faster, since few trials would be needed. The problem with using this procedure, however, is that it ignores the large variability in RT that is due to factors other than the independent variables. RT varies from trial to trial, even if the stimulus does not.
E-Prime User’s Guide Appendix B: Considerations in Research The main thing to note about the example above is that a within-subjects design is clearly better, if it is appropriate to use it, because it effectively increases sample size. But there are severe limitations to its use as well.
E-Prime User’s Guide Appendix B: Considerations in Research accuracy trade-off, because the subjects may be sacrificing (trading) lower accuracy for greater speed. That is, they may be faster on those trials because they are pushing themselves for speed, but ignoring the higher error rate that often goes with that effort. Consider the comparison of RT's in the letter-identification task.
E-Prime User’s Guide Appendix B: Considerations in Research as the number of responses becomes larger. This effect is not usually of much concern, but must be kept in mind when comparing the results of several experiments (i.e., if they used different numbers of response alternatives, the RT's cannot be directly compared). Intensity and contrast At least for low levels of illumination, the more intense the stimulus, the faster the RT.
E-Prime User’s Guide Appendix B: Considerations in Research Statistical Analysis of RT Data While this brief review of single-trial RT research cannot include an extensive discussion of data analysis, a few points deserve comment. The typical analysis of single-trial RT data employs the analysis of variance (ANOVA) to compare mean RT’s under various treatment conditions as defined by the levels of the independent variables. For within-subjects variables, a repeated-measures ANOVA is employed.
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E-Prime User’s Guide Appendix C: Sample Experiments Appendix C: Sample Experiments The E-Prime installation includes sample experiments illustrating some of the essential elements with E-Studio: BasicRT – A basic RT task presenting text. PictureRT – A basic RT task presenting bitmaps. SoundRT – A basic RT task presenting text and audio stimuli simultaneously. NestingRT – A basic RT task using the nesting feature of the List object. SlideRT – A basic RT task using the Slide object for stimulus presentation.
E-Prime User’s Guide Appendix C: Sample Experiments The TrialList defines the variables to be used within the experiment as attributes, the levels for the attributes, and the number of repetitions for each of the levels (i.e., set in the Weight attribute). The properties for the TrialList are set to randomly select a value for Stimulus out of the available exemplars, and to reset after all of the exemplars have been chosen. Figure 1. TrialList defines the Stimulus and CorrectAnswer attributes.
E-Prime User’s Guide Appendix C: Sample Experiments The FeedbackDisplay object named “Feedback” in the TrialProc organizes the feedback to be presented in relation to the input collected by the Stimulus object. Change the stimulus The value of the Stimulus attribute may be changed by opening the TrialList object and modifying the values in the Stimulus column. For example, the Stimulus might be changed to enter a mathematical equation (e.g., 2 + 2).
E-Prime User’s Guide Appendix C: Sample Experiments In order to collect input during both the Stimulus and Mask presentations, extended input must be enabled. Refer to the Basic Reaction Time Example: Extended Input section of this appendix for more information. Add a prime To add a prime to be presented prior to the stimulus, insert a TextDisplay object in the TrialProc timeline before the Stimulus object. Enter the Prime text and set the duration in the Properties for the new object.
E-Prime User’s Guide Appendix C: Sample Experiments Basic Reaction Time: Pictures The PictureRT experiment illustrates a simple reaction time experiment, presenting a fixation and a stimulus picture, and collecting a response to the stimulus. The PictureRT experiment illustrates the use of the List object, the ImageDisplay object, the Procedure object, and the FeedbackDisplay object.
E-Prime User’s Guide Appendix C: Sample Experiments The trial Procedure (TrialProc) consists of a TextDisplay object (i.e., Fixation) used to present a fixation prior to the stimulus display, an ImageDisplay object (i.e., Stimulus) used to present a picture of a red car or a blue car, and a FeedbackDisplay object (i.e., Feedback) used to present the appropriate feedback (i.e., correct, incorrect, etc.).
E-Prime User’s Guide Appendix C: Sample Experiments Present multiple pictures, or a combination of text and pictures The ImageDisplay object is ideal for single picture presentation. Combinations of pictures and text may be displayed simultaneously by using the Slide object. The image below illustrates a Slide object composed of two SlideImage sub-objects and a SlideText sub-object. Refer to the Basic Reaction Time Example: Slide section of this appendix for more information.
E-Prime User’s Guide Appendix C: Sample Experiments The SoundFile attribute is used in the Filename field of the properties for the SlideSoundOut subobject. At run-time, the SlideSoundOut refers to the TrialList object in order to resolve the value for SoundFile. The Sound device is enabled via the Devices tab in the Properties pages for the Experiment object. The properties for the Sound device may be edited by selecting the Sound device, and clicking the Edit button.
E-Prime User’s Guide Appendix C: Sample Experiments Basic Reaction Time: Nested Lists The NestingRT experiment illustrates a simple reaction time experiment presenting a fixation and a text stimulus, and collecting a response to the stimulus. The NestingRT experiment illustrates the use of nested List objects and the colon syntax to sample stimuli from more than one List during the same trial, and sample multiple stimuli from the same List during a single trial.
E-Prime User’s Guide Appendix C: Sample Experiments The Nested attribute in the TrialList defines the List objects from which the exemplars will be sampled in order to resolve the values for Word and NonWord in the Stim1 and Stim2 columns. The colon syntax (e.g., [Word:0], [Word:1], etc.) directs E-Prime to sample a specific number of times from the appropriate List. The colon syntax default value is 0, which samples one time from the designated List.
E-Prime User’s Guide Appendix C: Sample Experiments Input is enabled by the Stimulus object, and continues through the presentations of the second stimulus and the mask (i.e., the Stimulus2, Mask, and ClearMask objects). While the Duration field determines the duration of the Run method for the object, the Time Limit field sets the amount of time allowed for input. The Stimulus object’s Run duration is set to 500msec.
E-Prime User’s Guide Appendix C: Sample Experiments The setting for the End Action field determines the action to be taken upon input from the subject. The Jump option indicates that the program execution will jump to the Label object named DoFeedback in the current Procedure (see Structure view above) when input is received, skipping the other objects in the procedure if they have not yet been run (e.g., Mask).
E-Prime User’s Guide Appendix C: Sample Experiments The TrialList defines the variables to be used within the experiment as attributes, the levels for the attributes, and the number of repetitions for the levels (i.e., the Weight attribute). The SlideRT experiment uses the StateName attribute to choose from four different SlideState objects on each trial. Each SlideState is created by using the Add State tool on the Slide tool bar, and is represented as a different tab within the Slide object.
E-Prime User’s Guide Appendix C: Sample Experiments Each of the SlideState objects shows an asterisk in one of the possible positions. Each has a unique name, and is listed as level in the StateName attribute in the TrialList. In the Property pages for the Slide object, the Slide calls one of the four SlideState objects via its ActiveState property. The ActiveState property determines which SlideState will be presented on each trial.
E-Prime User’s Guide Appendix C: Sample Experiments Figure 1. Selecting the sub-object on the Slide. Figure 2. Set the BackStyle to transparent. Display Sub-Areas in Color To set the background for a specific part of the Slide object, select the sub-object defining that area, set the BackStyle property to “opaque”, and set the BackColor property to the desired color from the drop-down box. Each sub-object maintains its own properties, so each may be set to a different color, size, font, etc.
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E-Prime User’s Guide Appendix D: Display Presentation Appendix D: Display Presentation The figure below illustrates the three basic steps involved in the perception of a stimulus on a computer screen. The inset graphs show the time course over a 100ms period. The first step is writing the stimulus to the video memory. A display command in the source code of an experiment instructs the program to write information to the memory on the video controller card.
E-Prime User’s Guide Appendix D: Display Presentation Step 1 - Writing to Video Memory When a display command is executed, it writes data into a video controller card. This card has a certain amount of memory that can be thought of as a direct representation of the computer monitor (i.e., each memory location corresponds to a screen location).
E-Prime User’s Guide Appendix D: Display Presentation dot is activated by an exponential function (see Figure 1 step 2), on an LCD the activation is a square wave signal (on for a given intensity during the time of the refresh). The LCD still has a refresh rate, which is the rate at which each dot is updated. Similar to the CRT, on the LCD the middle dot would be updated 7.14ms after the first dot of the screen (on a 70Hz monitor). The effect on the eye of a LCD and CRT display are indistinguishable.
E-Prime User’s Guide Appendix D: Display Presentation after the pixel has been refreshed, the pixel will decay for another few milliseconds, and the retinal activation will persist for substantially longer unless it is masked by another stimulus. Vis u a l Integration Raster Based V isual A c t ivation Activation S lide Based V isual A c t ivation Raster Display S lide Display 0 50 100 150 200 250 300 350 Tim e (ms) Figure 2.
E-Prime User’s Guide Appendix E: Object Execution Timing Appendix E: Timing of Object Execution The figures below indicate the timing of events that compose the execution of runnable objects within E-Prime. The first figure illustrates the events of a single object, while Figures 2 and 3 illustrate the relationships between multiple objects when using Event and Cumulative timing modes.
E-Prime User’s Guide Appendix E: Object Execution Timing Figure 2. Event mode timing with no PreRelease Duration is calculated from the actual onset time of the object. With Event-Event mode, the Duration of the object is maintained, and OnsetDelay is expected to be positive due to the processing time necessary to set up the next object. Actual Duration (B.OnsetTime - A.OnsetTime) Stimulus A remains until replaced with the next stimulus. B.FinishTime B.
E-Prime User’s Guide Glossary Glossary Term Administrator altered data files Analysis files (ANL) annotations attribute Definition E-DataAid permits the opening of files as an Administrator via the Admin Open command in the File menu. To open a file as an Administrator, the user must know the password for the machine. Opening a file as an Administrator permits access to the security restrictions for the opened file.
E-Prime User’s Guide Glossary Term compile Definition In E-Run, compile takes the generated EBS file from E-Studio and feeds it into the E-Basic compiler. The process of compiling checks the syntax of the EBS file contents to make sure that it is in an acceptable format to run. conflicts Incompatibilities or inconsistencies between two data files, which can lead to problems during a merge operation. context menu Collection of related commands pertaining to a specific object.
E-Prime User’s Guide Glossary Term E-Studio Definition The experiment development application within E-Prime. Event mode Timing that is maintained relative to an individual event. This mode attempts to ensure that the duration of each event remains accurate but allows the interstimulus-interval to vary (i.e., the actual event duration is the user-specified Duration for that event and no adjustments to the event's duration will occur).
E-Prime User’s Guide Glossary Term log level MEL Pro text file Definition Hierarchical level in the structure of the experiment at which the data is stored. For example, a typical experiment has a Session level, Block level, Trial level, etc. File containing data collected using MEL Professional which has been exported to a text file using the ANALYZE or DEDIT programs from MEL Professional. merge operation merged data files The process of merging a source file into a target file.
E-Prime User’s Guide Glossary Term Run script Definition Occurring during the execution of the E-Basic script file. Programming language code generated automatically by E-Studio based on the Experiment Specification (ES) file, or user-written code which is entered as part of the es file. Script window The Script window features two tabs, User and Full. The Full tab displays the entire script as generated based on the object placement and specification within E-Studio.
E-Prime User’s Guide Glossary Term Structure view sub-objects Definition A hierarchial representation of the experiment events and structure. An object which is part of another object (e.g., a SlideText object exists only on a Slide object). Summation object Summation objects are used to collect a series of observations, and perform calculations on the collection. target file File into which data files will be merged. termination Condition upon which the processing of an object ends (e.g.
INDEX A abort an experiment early ............................ 4, 54 Administrator..................................... 189, 203–6 open file as................................................. 204 password .................................................... 203 analysis .................................................... 191–98 batch..................................................... 195–96 binning ................................................. 193–94 examples distribution of RT .....................
distributing experiments .........................5, 67–70 license issues................................................ 69 E E-Basic .......................................................... 123 Context object............................................ 131 Help ........................................................... 128 InLine versus User script ....................127, 134 learning ...................................................... 124 steps for writing ..................................
Loops ....................................................... 144–47 M machine requirements .................. See installation MEL Professional .................................. 5–8, 206 merge ....................................................... 166–73 conflicts ............................................... 173–76 Merge Log ................................................. 172 Recursive ..................................... 166, 169–72 Standard ...............................................
SoundRT........................ See sample experiments simultaneous presentation........................ A-44 stop/continue playback after response ..... A-44 spacebar ......................................................30, 42 Standard merge .........................................165–69 statistics ............................................ See analysis stimulus onset asynchrony (SOA) ....... See interstimulus interval Subject Station............................. See installation subroutines...........
