Detection of stimulus organization: Evidence of intelligence-related differences

Abstract

Utilizing checkerboard-like stimulus patterns varying with respect to symmetry and number of adjacencies, the effects of stimulus structure on the performances of mentally retarded and nonretarded subjects on a rapid-presentation match-to-sample task were examined. The disparity between target and distractor stimuli was manipulated across high, low, and moderate levels of stimulus organization. Consistent with previous findings (i.e., Caruso & Detterman, 1983) , detection rates for the two groups were equivalent at both high and low levels of distractor organization. Of particular importance, however, was that intelligence-related performance differences were evident only with distractors of intermediate organization. The influence of stimulus structure on stimulus detectability, and the implications of these findings for explaining intelligence-related differences across a wide range of tasks are discussed.