Abstract
Many accounts of sequential task control posit that when switching attention to a new task, inhibition is applied to aspects of the previously performed task. Such inhibition is most often measured behaviorally in the form of "backward inhibition," a performance cost associated with overcoming previously applied inhibition of a task upon its reactivation. Although much work has focused on how abstract task sets (e.g., color) are inhibited during task alternations, less attention has been devoted to the effects of alternations and repetitions of specific stimulus values (e.g., green) that occur within the task sequences typically employed in task switching designs. In this study we utilized electrophysiological and behavioral measures to compare task set, stimulus-value, and response level processing in a cued task switching paradigm in which participants alternated attention between two visual tasks. Behavioral results from both the color and shape tasks indicated longer response times (RTs) for trials in which the N-1 trial value was repeated (e.g., green to green vs. green to red) in task repetitions and for trials in which the lag-2 value was repeated (e.g., green to triangle to green vs. green to triangle to red) in task switch trials. These RT data are supported by converging evidence from event-related potential (ERP) measures, where larger target-locked P3 amplitudes were consistently observed in the value repeat and the lag-2 value repeat conditions for both tasks. The behavioral effects are in the opposite direction than would be predicted by value-level perceptual priming of the stimulus features and may suggest that specific value-level information is also inhibited with the task set. Taken as a whole, these results suggest that factors influencing the perceptual processing of the target stimulus should be taken into account in addition to the more commonly studied cue- and response-dependent processes when measuring task set inhibition.
Meeting abstract presented at VSS 2013