Two experiments were designed to show the influence of inhibition and planning on cognitive performance in relation with age and intellectual level. The results of Experiment 1 showed that children and old adults prove a significant weaker effect of intentional forgetting than young adults, due to a less efficient inhibitory mechanism. In the same time, children and old people had a significant poorer performance than young adults on cognitive planning task. These two experiments support the idea that cognitive development and decline might be influenced by the mechanisms that control information processing. Experiment 2 showed that there was a significant difference in intentional forgetting effect between children with medium IQ and mentally retarded children. However there was no difference in intentional forgetting between children with medium IQ and children with superior IQ. Children with superior IQ had a significant better performance than children with medium IQ and mentally retarded children, on cognitive planning task. These mean that inhibition is a basic process for normal intellectual functioning. Nevertheless superior performance is influenced by the strategy subjects use to solve the task.
KEYWORDS: inhibition, cognitive planning, cognitive development and decline, intellectual performance, control