Aging and Random Task Switching: The Role of Endogenous Versus Exogenous Task Selection

摘要

Task switching experiments have emphasized two robust effects that arise when individuals are required to shift between competing tasks: Mixing costs (MCs), which indicate less efficient performance in mixed-task versus single-task conditions, and switch costs (SCs), which reflect differences between switch trials and repetition trials within mixed-task conditions. The current study examined how age-related differences in these effects were influenced by the method of task selection in two procedures. Results indicated that SCs were not disproportionately larger for older adults during an exogenous switching condition, but large age differences in MCs were present beyond the degree predicted by differences in baseline speed. In an endogenous switching condition, small age differences were present both for MCs and SCs, although further age differences were evident in older adults' reduced switch rates. These findings suggest that older adults are substantially slower at updating repeated task sets during exogenous switching, but partially counter these effects by adopting a more persistent within-set mode of processing during endogenous switching.