Academic journal article Memory & Cognition

Learning a Nonmediated Route for Response Selection in Task Switching

Academic journal article Memory & Cognition

Learning a Nonmediated Route for Response Selection in Task Switching

Article excerpt

Published online: 7 February 2015

© Psychonomic Society, Inc. 2015

Abstract Two modes of response selection-a mediated route involving categorization and a nonmediated route involving instance-based memory retrieval-have been proposed to explain response congruency effects in task-switching situations. In the present study, we sought a better understanding of the development and characteristics of the nonmediated route. In two experiments involving training and transfer phases, we investigated practice effects at the level of individual target presentations, transfer effects associated with changing category-response mappings, target-specific effects from comparisons of old and new targets during transfer, and the percentages of early responses associated with task-nonspecific response selection (the target preceded the task cue on every trial). The training results suggested that the nonmediated route is quickly learned in the context of target-cue order and becomes increasingly involved in response selection with practice. The transfer results suggested that the target-response instances underlying the nonmediated route involve abstract response labels coding response congruency that can be rapidly remapped to alternative responses, but not rewritten when category-response mappings change after practice. Implications for understanding the nonmediated route and its relationship with the mediated route are discussed.

Keywords Response congruency · Categorization · Memory retrieval · Response selection · Task switching

Task-switching research has generally focused on the performance of well-practiced tasks involving frequently repeated target stimuli and fixed response mappings (for reviews, see Kiesel et al., 2010; Vandierendonck, Liefooghe, & Verbruggen, 2010). Practice effects have been analyzed in some studies (e.g., Buchler, Hoyer, & Cerella, 2008;Logan &Schneider,2006; Minear & Shah, 2008), but rarely at the level of individual target presentations to assess item-specific learning (Waszak, Hommel, & Allport, 2003), even though such learning could influence how responses are selected in ambiguous task-switching situations. In the present study, we investigated the time course of learning for individual targets in a task-switching context to achieve insight regarding the development and characteristics of a nonmediated route for response selection.

A distinction can be made between two routes for response selection in task-switching situations: a mediated route and a nonmediated route (Kiesel, Wendt, & Peters, 2007;Meiran& Kessler, 2008; Schneider, 2014, 2015; Schneider & Logan, 2009, 2014). The mediated route involves categorizing a target with respect to one or more tasks, then using the instructed category-response mappings to choose a response. The route is mediated because the intermediate step of categorization is performed (i.e., target [arrow right] category [arrow right] response). The nonmediated route involves using a target to retrieve a response directly from long-term memory following instance-based learning of target-response associations during practice (Logan, 1988, 2002). The route is nonmediated because the intermediate step of categorization is omitted (i.e., target [arrow right] response). If a target's categories are mapped to different responses or a target is directly associated with different responses, then a task cue is needed to resolve the ambiguity and enable selection of a task-appropriate response.

Evidence supporting the existence of the mediated and nonmediated routes has come from studies of response congruency effects in task-switching performance (for an overview, see Schneider, 2015). To understand response congruency, consider an experiment in which origin (living or nonliving) and size (small or large) judgments are performed on the referents of target words (e.g., mosquito, camel, dime, boulder). If the two categories for each task are mapped to different response keys, with both tasks involving the same pair of keys (e. …

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