Is task switching nothing but cue priming? Evidence from ERPs

Abstract

74The task-switching paradigm has become an important tool for study of the cognitive control processes needed to flexibly adjust to a changing environment (for a review, see Monsell, 2003). In a typical task-switching experiment, participants have to switch between two or more tasks, and differences in response times (RTs) and accuracy between task alternations and task repetitions-that is, the so-called switch costs-are typically interpreted as a reflection of the processing demands involved in changing task-specific cognitive configurations. However, recent evidence has posed a challenge to this interpretation of task-switch costs, as assessed in one variant of the taskswitching paradigm-that is, the task-cuing paradigm.In the task-cuing paradigm, tasks vary randomly from trial to trial, and a cue presented in advance indicates the relevant task. In contrast to alternative task-switching variants (e.g., that of Rogers & Monsell, 1995), the task-cuing p paradigm allows precise temporal control over both cueassociated preparatory processes and stimulus-associated p processes involved in resolving stimulus-triggered comp petition. However, as noted independently by Logan and Bundesen (2003) and , in the standard task-cuing paradigm, a task switch is always confounded with a switch of the task-indicating cue: Whenever the task switches, the cue switches as well; whenever the task stays the same, the cue also stays the same. To handle this problem, both groups introduced a new variant r in which two cues were mapped to each task, allowing for examinations of task switching independently from cue switching. From such 2:1 mappings, three different trand sition types result: regular no-switch transitions (cue and task repetition); regular task-switch transitions (cue and task switch); and a new type of transition, in which cue changes are associated with task repetitions (cue-switch condition). Using this method, both studies reported substantial costs for cue switching at short cue-stimulus intervals (CSIs), even when the task remained constant. The studies, however, differed in their findings concerning the actual task-switch costs. Whereas the data in the Logan and Bundesen (2003) study suggested that task-switch costs r are almost completely attributable to a cue switch, Mayr r and Kliegl (2003) observed actual task-switch costs over t and above the costs from a cue switch. These discrepant findings resulted in two different theoretical approaches to account for task-switch costs in the cuing paradigm. account starts with the simple assumption that working memory can contain only one coherent task set at a time, so that each task-switching trial requires updating working memory and the attentional configuration to reflect the current task demands. This updating process comes in two stages (for similar twoprocess approaches, see Meiran, 1996 Recent findings suggesting that switch costs in the task-cuing paradigm are largely attributable to a change in the task-indicating cue have been interpreted in terms of a pr...

Control and interference in task switching—A review.

“…For example, a recent ERP study, which allowed an online measurement of cue-triggered processes, revealed that both switch and repetition trials elicit a P3b component (Jost, Mayr, & RosIer, 2008). These authors assumed that the P3b in the preparatory interval reflects endogenous or cognitive aspects of "context updating" (see Donchin & Coles, 1988) because the P3b amplitude was related to response speed.…”

“…They demonstrated that the switch-related positivity occurred regardless of whether cue category repeated or switched. Jost et al (2008) directly compared ERPs in task-switch trials and cue-switch trials and found a relative negativity starting 400 ms after presentation of the target stimulus. This effect differed regarding timing and topography from the effect between cue-switch trials and cue-repetition trials, providing evidence for distinct task processing in taskswitch trials compared with cue-switch trials.…”

At will or not at will: Electrophysiological correlates of preparation for voluntary and instructed task-switching paradigms

“…Some authors have directly related this positive deflection to the P3b component as the construct of "context updating" (Donchin & Coles, 1988), which suggests that the increased positivity is assumed to reflect the endogenous control for comparison of the attributes of incoming stimuli with an internal model and the subsequent revision of the model (Barcelo, MunozCespedes, Pozo, & Rubia, 2000;Barcelo, Perianez, & Knight, 2002;Kieffaber & Hetrick, 2005). Accordingly, the late posterior positivity for switch trials has been interpreted as the advanced endogenous control processes that either update the task sets (Barcelo et al, 2002;Kieffaber & Hetrick, 2005) and/ or the stimulus-response (S-R) mapping rules (Astle, Jackson, & Swainson, 2008) in working memory or retrieve the task goals from long-term memory (Jost, Mayr, & Rosler, 2008). Furthermore, a less common finding in the ITS paradigm is the late frontal negativity 1 (LFN) for switch trials that occurs in advance of the target presentation (Astle et al, 2008;Lavric, Mizon, & Monsell, 2008;Mueller, Swainson, & Jackson, 2007).…”

Brain oscillatory activity associated with task switching and feedback processing

“…Nevertheless, even in this setup, reinforcement learning mechanisms could be taking place during the cuing period, since participants could adjust their correct or incorrect predictions of their previous response on the basis of repeat and switch cues, respectively. In another set of task-switching and WCST studies, cues signaling a readjustment of the task rule and cues signaling the correctness of the performance have been separated and introduced in distinct stages of the trial series (Adrover-Roig & Barceló, 2010;Jost et al, 2008;Kieffaber & Hetrick, 2005;Periañez & Barceló, 2009). In all of these studies, however, the analyses of the electrophysiological responses elicited by the feedback signals have been omitted.…”