A More Complete Task-Set Reconfiguration in Random than in Predictable Task Switch

Abstract

Three experiments are presented that compare the cost found when switching from one task to another in two different conditions. In one of them, the tasks switch in predictable sequences. In the other condition, the tasks alternate at random. A smaller time cost is found in the random-switch condition when enough preparation time is allowed. Such an effect is due to the random-switch cost continuing to decrease with preparation time after the predictable-switch cost has reached an asymptote. Although the relationship between number of repetitions of one task and time cost is different in the random- and the predictable-switch conditions, only the latter shows the presence of an "exogenous" component of cost. The implications of this finding are discussed in relationship with the usual distinction between an endogenous component of switch cost that is affected by preparation time and another exogenous, residual component (e.g., Rogers & Monsell, 1995). It is proposed that a different kind of task-set preparation is at work when tasks alternate at random.

Task switching under predictable and unpredictable circumstances

“…In their data, switch costs were generally larger under predictable than under unpredictable conditions, and costs did decrease as RSI increased. Notably, though, switch costs were present in data for the unpredictable condition at the longest RSI (i.e., 1,500 msec), and this contrasts with the findings reported by Tornay and Milán (2001). However, given the procedural differences across the two studies, the reasons for the contrasting patterns of findings remain unclear.…”

“…Aligned to this was the aspiration to see whether switch costs under unpredictable conditions would occur at the longest (i.e., 1,200-msec) RSI (cf. Tornay & Milán, 2001). …”

“…With explicit cuing, the claim is that the tasks are unpredictable because the order of the tasks is randomized (see Monsell, Sumner, & Waters, 2003): The nature of the upcoming task is signaled by a precue that is displayed during the RSI. Such experiments have been reported by Tornay and Milán (2001). They examined performance in what they termed predictable and random conditions.…”

“…The principal aim was to examine both exogenous and endogenous factors in a bid to illuminate the cognitive processes that underlie task switching. Predictions made by Sohn and Anderson (2001) were central, but each of the experiments also allowed us to examine the pattern of performance reported by Tornay and Milán (2001). To what extent can task set reconfiguration be accomplished when the upcoming task is unpredictable?…”

An integrated model of cognitive control in task switching.

“…The reconfiguration metaphor has been a potent influence on how task-switching research is framed (e.g., De Jong, 2000;Kleinsorge & Gajewski, 2004;Monsell, 2003;Rubinstein, Meyer, & Evans, 2001;Steinhauser et al, 2007;Tornay & Milan, 2001). The basic hypothesis is that latency switch cost reflects processing that is directly functionally related to cognitive control; in other words, "switch cost might seem to offer an index of the control processes involved in reconnecting and reconfiguring the various modules in our brains, so as to perform one task rather than another" (Monsell & Driver, 2000, p. 16).…”