ABSTRACT
In chapter 3, I surveyed some of the empirical results and theories that pertained to the detection of visual forms. In that discussion theories were considered that were intended to explain the outcome of experiments in which the observer was asked to answer a question that was typically structured in the prototypieal manner: "Is anything there?" Our attention is now directed to another task-another prototypieal question-that of the visual discrimination of forms. In this case, observers are presented with what is informationally a much more demanding challenge in that they have to not only detect the two forms that are to be compared but also to perceive a sufficient amount of detail so that whether they are the same or different can be specified. Furthermore, the answer to this question is often not so simply dichotomous as it may at first be represented. Same or different judgments are extremes of a continuum, of course, and the decision may be graduated in that the observer can be directed to respond to a query asking to what degree two stimuli are similar.
