Age-Differential Effects of Proactive Control in Dual Tasking: The Moderating Effect of Task Difficulty

Dual tasking refers to the ability to perform two concurrent tasks. Using the psychological refractory period (PRP) paradigm, two experiments examined whether providing a prompt that facilitated proactive control could benefit dual-task performance among younger and older adults. In Experiment 1, difficulty-related prompt words (“difficult,” “easy,” or null) were presented before easier dual tasks with a longer stimulus onset asynchrony (SOA) of 800 ms or harder tasks with a shorter SOA of 100 ms. Experiment 2 extended the investigation by presenting these prompts (“difficult” or “easy”) before dual tasks with a fixed SOA of 150 ms. It also examined the moderating effects of actual task difficulty by manipulating task congruency. Both experiments suggested that proactive control triggered by difficulty-related prompts facilitated dual-task performance in both age groups. Notably, prompts benefited younger adults’ dual-task performance only when the actual task difficulty was relatively higher, but they benefited older adults’ dual-task performance regardless of the actual task difficulty. These findings contribute to our understanding of proactive control and the different effects of prompts on cognitive performance among younger and older adults.