Ten young males (aged 16-to-22 years) whose IQ scores ranged from 51 to 77 were compared on a simple discrimination task with ten male university students (aged 18-to-23 years) and 28 nonretarded male children (aged 7-to-11 years) in order to determine if reaction time is a consequence of mental retardation.

Children with mental retardation are particularly prone to failure on relational tasks such as oddity and match-to-sample, suggesting a differential sensitivity to relational information. This paper reports on several studies in which characteristics of stimulus arrays were enhanced. Results demonstrated the theoretical and practical significance…

Reports the results of two experiments dealing with children's visual and tactual performance. In the first task, after several presentations of a series, the tactual group made almost errorless discriminations. But with memory demands, tactual performance became poorer than visual performance. Found a large developmental difference. (JAC)