Specifications

41
Analysis of Evaluation
Once all the evaluations were carried out the group sat down
and studied the recording of the tapes. There are a number of
principles that can be used to evaluate a product; we have chosen to
evaluate the projector by studying its affordances and constraints. By
do the analysis in this way we can see the overall positive and
negative aspects of the remote control and on-screen menus instead of
the aspects that were involved in each task we asked the users to
carry out.
Affordances
James Gibson first defined the term affordance in 1977. Gibson
definition referred to an animal’s visual perception in the wild. There
were a number of properties of affordance. An affordance exists
relative to the capabilities of the animal. Gibson gave the example of a
flat rigid surface that affords support to the animal. But the existence
of that affordance is independent of the animal’s ability to use it and
the affordance does not change as the needs of the animal changes.
(McGrenere 2000)
Don Norman in his book The Design of Everyday Things
(Norman 1988) popularised the concept of affordance within the field
of HCI. Norman’s definition of affordance was commonly
misunderstood and he later broke up affordance into perceived and
physical affordance. This was later expanded on further by Rex
Hartson (Hartson 2003) into four different types of affordance: