Delayed Match-to-Sample Early Performance Decrement in Monkeys after 60 Co Irradiation

BRUNER, A., BOGO, V., AND JONES, R. K. Delayed Match-To-Sample Early Performance Decrement in Monkeys After 6Co Irradiation. Radiat. Res. 63, 83-96 (1975). Sixteen monkeys were trained on a delayed match-to-sample task (DMTS) based on shock avoidance and irradiated with single, whole-body exposures of from 396 to 2000 rad 6"Co (midbody dose) at between 163 and 233 rad/min. Pre- to postirradiation performance changes were assessed using a penalty-scaling measure which differentially weighted incorrect responses, response omissions, and error-omission sequences. Thirteen of the animals displayed early performance decrement, including five incapacitations, at lower doses (<1000 rad) than heretofore found effective. This was considered a function of task complexity, measurement sensitivity, and gamma effectiveness. The minimum effective midbody dose for inducing decrement using the DMTS task was estimated to be on the order of 500 rad. The nature of early, transient performance decrement seems to reflect more of an inability to perform than an inability to perform correctly