LACK OF CONSISTENT INDIVIDUAL-DIFFERENCES IN RATS ON TASKS THAT REQUIRE RESPONSE-INHIBITION

Hungry rats performed four different tasks which all required responding to be withheld for food reinforcement to be obtained. The tasks were the following: an omission schedule, a go/no-go procedure, a differential reinforcement of low rate schedule, and a choice task in which the subject could respond for a small immediate reward ora large delayed reward. Each rat experienced each task twice. For each task, the rank ordering of the subjects' performance on the test and retest was highly consistent, indicating the reliability of the task for measuring a particular ''ability.'' However there were no consistencies in the performance of individual rats between tasks. This suggests that claims regarding consistent individual differences in brain-lesioned nonhumans across a range of such tasks are not supported in intact subjects.