MENTAL-RETARDATION AND INSPECTION TIME - A 2-STAGE MODEL FOR SENSORY REGISTRATION AND CENTRAL PROCESSING

  • 1 January 1984
    • journal article
    • research article
    • Vol. 89  (1) , 83-90
Abstract
Mildly mentally retarded and nonretarded young adults were compared in simple visual discimination tasks from which can be derived an estimate of inspection time (.lambda.), assumed to reflect the time taken by some basic component in the decision process. In the 1st experiment retarded and nonretarded subjects'' performance showed improvement in a condition employing a backward mask to limit the duration of sensory information available to subsequent central processes, but substantial group differences in .lambda. remained unchanged. When target stimuli were presented for short durations, but without interruption by masking, retarded subjects performed less effectively than did nonretarded subjects and, despite extensive practice, did not achieve nonretarded subjects'' levels. A postulated 2-stage serial model of discrimination was tested in the 2nd experiment. Concurrent manipulation of 2 factors confirmed that: .kappa. involves initial sensory registration followed by central processing; for both groups these stages are independent; and poorer performance among retarded subjects is the consequence of deficiencies at both stages.