Aging, inhibition, and verbosity.

The hypothesis that off-target verbosity, defined as extended speech that is lacking in focus or coherence, is mediated by an age-related decline in the ability to inhibit task-irrelevant thoughts, was evaluated in a sample of 205 community-dwelling elderly volunteers aged 61-90. Results showed that performance on four tasks that measured the ability to suppress or remove irrelevant information stored in working memory accounted for a significant proportion of the variance in verbosity, whereas performance on other cognitive measures was unrelated to it. Shared effects between the measures of the ability to inhibit task-irrelevant information and age suggested that age declines in this particular ability may underlie previously observed age-related increases in verbosity. In contrast, the contribution of psychosocial factors to explained variance in verbosity scores was relatively independent of that of inhibition-related measures and age. The results were discussed as suggesting a possible frontal lobe involvement in off-target speech.