حافظه بلند مدت و کنترل کنترل توجه

Abstract Task-switch costs and in particular the switch-cost asymmetry (i.e., the larger costs of switching to a dominant than a non-dominant task) are usually explained in terms of trial-to-trial carry-over of task-specific control settings. Here we argue that task switches are just one example of situations that trigger a transition from working-memory maintenance to updating, thereby opening working memory to interference from long-term memory. We used a new paradigm that requires selecting a spatial location either on the basis of a central cue (i.e., endogenous control of attention) or a peripheral, sudden onset (i.e., exogenous control of attention). We found a strong cost asymmetry that occurred even after short interruptions of otherwise single-task blocks (Exp. 1–3), but that was much stronger when participants had experienced the competing task under conditions of conflict (Exp. 1–2). Experiment 3 showed that the asymmetric costs were due to interruptions per se, rather than to associative interference tied to specific interruption activities. Experiment 4 generalized the basic pattern across interruptions varying in length or control demands and Experiment 5 across primary tasks with response-selection conflict rather than attentional conflict. Combined, the results support a model in which costs of selecting control settings arise when (a) potentially interfering memory traces have been encoded in long-term memory and (b) working-memory is forced from a maintenance mode into an updating mode (e.g., through task interruptions), thereby allowing unwanted retrieval of the encoded memory traces.

1. Introduction The way we interact with the world is contingent on abstract control settings. These settings specify which external or internal information is currently relevant and how to act upon it in order to achieve one’s goals. From research with the task-switching paradigm, in which people are prompted to switch between predefined task rules on a trial-by-trial basis, we know that it is difficult to flexibly change between task or control settings (for reviews see Kiesel et al., 2010, Monsell, 2003 and Vandierendonck et al., 2010). From this research we can also derive two fundamentally different accounts of how exactly these obstacles to flexible change arise. By the first, and intuitively most appealing account, costs of switching between tasks or control settings come from the direct clash between the residue of the most-recently used and the currently relevant task setting (e.g., Allport, Styles, & Hsieh, 1984; Gilbert and Shallice, 2002, Yeung and Monsell, 2003a and Yeung and Monsell, 2003b). In contrast, the second account holds that interference between competing task settings is not the result of carry-over from the most-recent past, but rather reflects the long-term memory (LTM) knowledge base about the space of tasks involved in a particular context (e.g., Bryck & Mayr, 2008; Mayr, 2009; Waszak, Hommel, & Allport, 2003).1 In the work described here, we examine which of these two accounts is better suited to explain the costs of selecting and changing control settings. For this purpose, we focus mainly on the important, yet understudied problem of selecting between endogenous vs. exogenous control over spatial attention. Before we elaborate on our choice of control settings, we first develop our general theoretical and empirical approach.