The ability to activate and inhibit speeded responses: separate developmental trends.

When children grow older they respond faster and are less susceptible to interference caused by task-irrelevant information. These observations suggested the hypothesis that a global mechanism may account for developmental change in the speed of responding and that inhibitory function may underlie the ability to activate speeded responses. The current study examined these issues by comparing the performance of 4 age groups (5-, 8-, and 11-year-olds and young adults) on a battery of 6 speeded performance tasks, 4 of which required the inhibition of response activation. An analysis of reaction and inhibition times supported a hypothesis of generalized developmental changes in response activation, but revealed a less pronounced development of inhibition. A nonselective mechanism of response inhibition seems to be fully developed during early childhood.