Strategies for stimulus selective stopping in the elderly.

This study consisted of two primary aims: (1) to determine if different age groups exhibited different strategies (based on their behavioral reaction time [RT] patterns) while performing a stop-signal task and (2) whether there were age-related differences in reactive and/or proactive control processes. Twenty-four younger adults (20-30years) and 24 older adults (61-76years) participated in this study. Participants performed a stop-signal task, which included a choice RT block, global stop-signal block, and stimulus-selective stop-signal block. Participants' strategies were classified using the Bayes factor to support or reject the null hypotheses at the individual level based on paired comparisons among the mean no-signal, signal-respond, and ignore RTs. We found that older adults used a similar pattern of strategies as younger adults in performing a stimulus-selective stop-signal task; most of them utilized either the Stop then Discriminate strategy or Discriminate then Stop strategy with dependency between go and stop processing. In addition, while older adults exhibited an impaired reactive control deficiency reflected on their increased stop-signal RTs in the stimulus-selective stop-signal task, they did not show an impaired proactive control process because their go trials' RT differences between the choice RT and stop-signal blocks did not differ significantly from those of young adults.