Performance in a delayed comparison discrimination task as a function of stimulus interpretation

In a sequential same-different comparison task, physically similar visual stimuli with the same interpretation were more poorly discriminated than equally similar stimuli with different interpretations. Physical similarity of stimulus pairs was held constant by using parametrically controlled computer-generated visual forms and by using each pair of figures as both a sameinterpretation pair and as a different-interpretation pair. The interpretation variable used the ambiguous-figure properties of the forms. The two forms in each pair could be seen as representing the same object given one way of interpreting them; a second interpretation applied to only one member of the pair. The discrimination results held for interstimulus intervals of 300 msec and 13 sec. Similarities between the present studies and “categorical perception” studies are noted.