Conflict resolution and adaptation in normal aging: the role of verbal intelligence and cognitive reserve.

The present study investigated effects of cognitive aging on conflict resolution (the ability to suppress prepotent and distracting, irrelevant information) and conflict adaptation (the adjustment of conflict resolution based on previously experienced conflict level). In addition, it aimed at investigating whether Cognitive Reserve (CR) and intelligence play a compensatory role against age-related deficits in both factors. A color-word Stroop task with no feature repetitions (i.e., neither the word nor the color was repeated in two subsequent trials) was administered to 23 older adults with no dimentia (65-79 years old) and 22 younger controls (18-34 years old), in addition to measures of intelligence and CR. Older adults' performance was characterized by general slowing. However, response slowing inversely correlated with intelligence, education, and a cognitive-reserve index. The Stroop effect (i.e., response-time (RT) difference between incongruent and congruent conditions) was larger in older adults than in younger controls, and in the older group only, it negatively correlated with verbal IQ. With this feature-repetitions-free Stroop task, we confirmed the presence of some conflict adaptation effects, which, however, were spared by aging. Altogether, these findings show that older adults can cope better with age-related impairment in verbal interference resolution, if they have enough intelligence resources in a related (verbal) domain, whereas CR plays a role in general performance speed only. We therefore suggest that general and specific accounts of cognitive aging may apply to different processing stages, which are influenced by partially different compensatory factors.