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Inhibition has been implicated as an important mechanism for task-set control, ensuring the efficient selection of the to-be-performed task over alternative possibilities. Across three experiments we demonstrated the effects of two potentially different types of task inhibition. The first is the inhibition of a task that concurrently affords an incongruent response, which is labelled dimension inhibition (Goschke, 2000). Using targets that afford three tasks, we demonstrated that this only occurs when a single alternative task affords an incongruent response, with the inhibition being specific to that task. The second type of inhibition that we observed was backwards inhibition—the suppression of a recently abandoned task-set (Mayr & Keele, 2000). Unlike dimension inhibition, backwards inhibition was not triggered by the response incongruence of the unperformed tasks, or even whether the target afforded responses via the unperformed tasks. These two purported types of inhibition did not co-occur, and neither did the factors of response congruence and whether that task was recently abandoned interact. We therefore suggest that task-specific inhibition can be applied/triggered differently depending upon the paradigm, perhaps depending upon the extent to which alternative tasks, and therefore potentially other responses, are triggered by the target. [ABSTRACT FROM AUTHOR]

Castel, Pratt, and Craik (2003) have shown that inhibition of return (IOR, the delayed response to a recently cued item) is disrupted by a secondary task that involves spatial working memory (WM), and they suggest that IOR is mediated by spatial WM. However, they did not specify what kind of IOR was involved. We used a dual-task paradigm to examine whether the two kinds of IOR (location- and object-based IOR) are affected by two kinds of secondary task that involve spatial and nonspatial WM, respectively. The results show that location-based IOR was disrupted by a spatial secondary task while the object-based IOR was disrupted by a nonspatial secondary task. The present study further elaborates the conclusion of Castel et al. (2003) by differentiating the effect of the two kinds of WM (spatial vs. nonspatial) on the two kinds of IOR (location based vs. object based). [ABSTRACT FROM AUTHOR]