Cognitive aging and inhibitory efficiency in the Daneman and Carpenter's working memory task.

This study tests the hypothesis that the ability to inhibit already processed and actually irrelevant information influences performance in the reading span task (RST). French versions of the Stroop color-word task and of the Daneman and Carpenter's RST were administered to 151 participants from 30 to 80 years. In addition to the traditional span score, a score of vulnerability to intrusions was also computed as the number of intruding responses (words from preceding trials of the RST or nonfinal words). An analysis of variance showed a significant age effect on the reading span and on the resistance to interference, but no significant age effect on the vulnerability to intruding responses. A multiple-regression analysis was also made with the reading span score as the dependent variable, and with age, vulnerability to intrusions, and resistance to Stroop interference as independent variables. This analysis revealed that there was a relation between participants' vulnerability to intruding responses and their working memory span scores; the contribution of age and resistance to interference were very weak. In conclusion the present findings first support the idea that the working memory capacity undoubtedly involves some inhibitory control; however, because the participants' vulnerability to intruding responses is not clearly affected by age, the present findings also suggest that some part of age effects upon the working memory span has to be explained by another factor than a growing inefficiency in inhibitory control.