Second, in line with the LTM memory account, we document the role of experienced conflict on encoding of LTM traces.

The cost asymmetry arises only when subjects have experienced conflict from the dominant task while performing the non-dominant task (Exp. 1). Third, we also examined the role of interruptions in determining the cost asymmetry. Consistent with the idea that interruptions have a structural effect (i.e., in terms of enforcing an updating process during recovery from the interruption), we demonstrated that the cost asymmetry could not be explained in terms of task-specific associative mappings (Experiment 3). Also, consistent with the structural hypothesis we demonstrated that the type, the attentional control demands, or the duration of interruptions have at best very

small effects on the cost asymmetry. Dasatinib concentration In line with our general model this suggests that what matters is not the interruption activity itself, but simply the fact that interruptions elicit a working-memory updating process. Fourth, an important aspect of the current work is that the interruption paradigm, combined with the exogenous/endogenous check details tasks provides a particularly clear empirical distinction between the updating mode (post-interruption trials) and the maintenance mode (exogenous-task maintenance trials). In standard task-switching situations it seems particularly difficult to bring subjects to adopt a pure maintenance mode, as the mere possibility of task switching may induce a tendency to update even on no-switch trials (e.g., Monsell & Mizon, 2006). A clear empirical distinction between updating and maintenance allows examining context and individual differences factors that could selectively affect these two modes of control and how people negotiate between them. We are currently using this paradigm to test

the hypothesis that older adults are “chronic updaters” (Mayr, 2001 and Spieler very et al., 2006). Our initial results indicate that while young adults exhibit virtually no trace of conflict from the endogenous task in exogenous-task maintenance trials (e.g., as in the exo/endo condition in Fig. 2), old adults continue to exhibit substantial costs and conflict effects across maintenance trials. This is consistent with the hypothesis that old adults find it difficult to revert to a full maintenance mode following an interruption. Combined, our results provide a powerful challenge to models that emphasize the clash between the immediate past and the present as the main driver of task-selection costs. In the following we discuss both implications of our results, as well as remaining challenges. We found that adopting an exogenous attentional setting after an interruption produces a larger RT cost than adopting an endogenous attentional setting. As noted, this pattern is similar to the switch-cost asymmetry found for other dominant vs. non-dominant task combinations in traditional task-switching situations.