The myth of perceptual defect: Sources and evidence.

Abstract

A hypothesis of a perceptual defect in black populations, suggested tentatively 20 years ago, was found to be still alive in the research literature. The hypothesis, its original data base, and more recent literature were examined. It was found that the hypothesis did not distinguish between the effects of race versus early experience on perceptual functioning. Reflecting this confusion, the original data base for the hypothesis was seriously flawed. Many studies assumed that the hypothesis could be demonstrated by lower scores on performance than on verbal subtests of IQ test batteries. The inadequacy of this assumption was discussed, and the use of IQ subtests to assess perceptual functioning was criticized. The need for measurement of response biases when attempting to assess group differences in perception was also stressed. An examination of the literature found few direct tests of ethnic differences in perception. Although some data tentatively suggest that there may be differences in visualization of spatial transformations, similar to the differences that have been found between the sexes, it was concluded that not enough data are available to make any general statement about ethnic differences in perception.

Practice Effects with Traditional Mental Test Items

“…For example, some groups may demonstrate lower levels of performance on tests of fluid intelligence as compared to tests of crystallized intelligence. The theory behind such dis-tinctions is weak (see, for example, Mandler & Stein, 1977;Sherman, 1978) and the evidence is inconsistent (Arvey, 1972). If the item types and tests used were also differentially subject to practice effects, then the inconsistency in results becomes explicable.…”

Pattern Reproduction In Two Cultures

“…In a recent review of research on perceptual memory tasks Mandler and Stein (1977) suggested that few, if any, ethnic differences had been demonstrated. However, one of the recurrent features of pattern reproduction studies in the cross-cultural setting has been the higher frequency of orientation errors produced by non-western samples.…”