Visual backward masking in retardates and normals

Educable adolescent male retardates were compared with normal males of equal CA and equal MA on a visual backward masking task. Significantly shorter interstimulus intervals were required to induce a masking effect in the equal-CA group than in the retarded and equal-MA groups, who did not differ from each other. Speed of visual processing is a function of MA. It is related to CA in normals. and to IQ when retardates are compared with equal-CA normals.     

Size constancy in children: a new interpretation

Existing evidence indicates that there are differences between children and adults in size constancy when observation distances are large. Findings are reported which suggest that this phenomenon is based on a difference in the accessing of proximal stimulus information, which, in the case of size, refers to visual angle subtended. Age differences were found when a traditional size constancy task was used, but these differences disappeared when all the comparison objects subtended the same visual angle. Since this finding demonstrates that young children can make accurate size matches, it is suggested that the underconstancy previously reported is not necessarily the result of children's inability to use fully certain cues to distance. Rather, the findings suggest that children access proximal stimulus information more spontaneously than do adults.     

The von Restorff effect and measures of organization in normals and retardates

Thirty-two noninstitutionalized retardates and 32 normals of equal mental age (approximately 8 years) heard 10 orders of 10 nouns when the decibel (dB) level of the stimuli was the same and when the dB level of the sixth item was higher. The yon Restorff effect was demonstrated by both groups. The normals’ overall recall was superior to that of the retardates’ recall. Differences in recall were attributed to the normals’ tendency to recall items in the same serial order more consistently. The subjective organization of lists, as measured by order of recall, differed for the normals and retardates; the normal group was more adaptable than the retarded group in adjusting their strategy to different list conditions.     

Size constancy in extended haptic space

When a stick is used to extend the boundaries of the world perceived by touch, haptic parallels to visual angle and size constancy appear. In a pilot study, Ss using a stick to feel an out-of-reach gap were more likely to underestimate its size than were Ss feeling a nearby gap with the index finger, but size constancy was relatively high with the stick. The main study, comparing judgments of gaps at intermediate and far positions, confirmed these findings. Errors were greater for the more distant gap, but constancy was high in both positions. Correlations between far and intermediate judgments indicated that Ss were consistent in the type of error made. Similar findings emerged from a partial replication with blind and partially sighted Ss.