SIZE CONTRAST AS A FUNCTION OF CONCEPTUAL SIMILARITY BETWEEN TEST ANDINDUCERS

In four experiments, the effect of the semantic relationship between t est and inducing stimuli on the magnitude of size contrast in an Ebbin ghaus-type illusion was explored. In Experiments 1 and 2, the greatest illusion was found when test and inducing stimuli were identical in s hape and differed only in size. Decreased size contrast was found when inducing stimuli were drawn from the same category as the test stimul us, but were not visually identical. Even less size contrast was found when inducing stimuli were from a near conceptual category, with the least effect when they were drawn from a completely different category . In Experiment 3, it was demonstrated that even if test and inducing stimuli are drawn with identical geometric elements, the size contrast illusion is greatly reduced if they represent apparently different co nceptual categories (through the manipulation of orientation and perce ptual set). In Experiment 4, any geometric or spatial confounds were r uled out. These results suggest that size contrast is strongly influen ced by the conceptual similarity between test and inducing stimuli.