Age-related differences in the maintenance and modification of automatic processes: arithmetic Stroop interference.

This experiment was designed to investigate whether well-learned "automatic" processes remain stable as a function of age, as well as to determine whether the ability to modify these automatic processes is disrupted for older adults. We used an arithmetic Stroop task to measure the stability of an automatic process. Nineteen young (mean age 22) and 19 old (mean age 75) adults participated in three experimental sessions, each of which consisted of 15 blocks of 30 trials. Although the young subjects had faster verification times overall than did the old adults, both young and old subjects showed significant interference effects. For the young adults, there was a decrease in the interference effect with practice, which suggested that they were learning to inhibit the automatic process of performing the arithmetical operation. However, the old adults showed no significant decrease in the associative interference effects. This implies that the older adults were impaired in their ability to inhibit automatic processes, even when those processes interfered with performance. Theoretical and practical training implications are discussed.