IMPAIRMENT IN THE PERCEPTION OF 2D SHAPE BY ADULTS WITH MILD INTELLECTUAL DISABILITY - AN EXPLORATORY INVESTIGATION

Following a necessarily brief review of evidence for perceptual impair ment associated with mild intellectual disability, two experiments are reported. Adults with mild intellectual disability and age-and gender -matched adults with average or above-average intelligence identified 16 two-dimensional random shapes after their progressive exposure movi ng past an aperture and after their brief full exposure while stationa ry. Identifications were made by pointing at the previously presented target shape randomly positioned among five similar shapes. In the fir st experiment, the aperture was narrow so that the target shape was ne ver fully visible, and in the second it was wider so that it was brief ly fully visible while moving. In both experiments, participants with intellectual disability made significantly more identification errors than those of the age-and sex-matched controls. The data are interpret ed as showing that individuals with intellectual disability are impair ed in their perception of both moving and stationary two-dimensional s hapes. It is suggested that the deficit shown by individuals with inte llectual disability may be due to the ''impoverishment'' of the moving stimulus shapes by progressive exposure in an aperture.