User`s guide

E-Prime User’s Guide
Chapter 2: Using E-Studio
Page 56
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.
Ø Finally, and most importantly, double check that all of the measures necessary for the
analysis are being logged.
Because E-DataAid offers filtering capabilities, it is recommended that the user err on the side of
logging too much information rather than failing to log some crucial variable.
2.9.3 Checking timing accuracy
The logging options within E-Prime allow for detailed monitoring of the timing of the events within
an experiment. It is important to log, examine, and monitor the timing information for
experimental events (see Chapter 3 – Critical Timing). On the Logging tab for each object, the
Time Audit and Time Audit (Extended) variables provide the means to verify the launch-time,
display-time, finish-time, and possible delay or error associated with each object.
2.9.4 Running pilot subjects
Usually, the person programming the experiment is too familiar with the instructions or the task to
be able to pick up errors or inconsistencies in the experiment. It is important to run pilot subjects
to iron out the wrinkles in the experiment prior to actual data collection.
2.9.4.1 Verifying the understanding of instructions
For the subject, the instructions may not be as clear as they were for the experimenter, who
certainly has more information concerning the purpose of the experiment. During the running of
pilot subjects, patterns of responding with inappropriate keys, low accuracy levels, or long
reaction times may be indicative that the subjects did not understand the task. Or, perhaps not
enough instruction was supplied (e.g., often experiments are run without written instructions, and
the experimenter verbally communicates the task to the subject).
It is generally a good idea to present subjects with illustrations of the sequence of displays they
will see on the computer and describe the task verbally before running it on the computer.
Subjects seem to be more likely to ask questions when presented with a scenario in paper form.
Put test questions into the instructions (e.g., “Now if you saw this sequence of stimuli, how would
Poor instructions result in irritated subjects and inaccurate responses. Pilot test the instructions,
being sure to run someone who does not have experience with the experiment. Clear
instructions will not only add to the consistency of the experiment, but will serve as a record of the
method used within the experiment when the experiment is passed on to a colleague or a
student.
2.9.4.2 Checking the data
After each pilot subject is run, the individual data files should be reviewed for accuracy prior to
merging them into a master data file. Monitoring of individual data files will help to eliminate
potential conflicts during merge operations.