Academic journal article Memory & Cognition

The Time Course of Task Switching: A Speed-Accuracy Trade-Off Analysis

Academic journal article Memory & Cognition

The Time Course of Task Switching: A Speed-Accuracy Trade-Off Analysis

Article excerpt

On each trial of this study, participants either switched between or repeated two simple, two-choice tasks involving either letter or digit classifications. Speed-accuracy trade-off (SAT) curves were obtained using the response-signal method of eliciting speeded responses at various response time lags after the presentation of the stimulus for the second task. The key finding from separate analyses of the three SAT-curve parameters (intercept, rate, and asymptote) was that the location of the intercept of the SAT function (i.e., the point at which responding rises above chance) was shifted upward for both short and long response-stimulus intervals under task-switch conditions but only when the responses associated with each of the letter-digit stimulus components were incompatible.

Response time (RT) and accuracy are highly dependent (Pachella, 1974). Typically, more efficient information processing results in both decreases in RT and increases in accuracy. However, in any response process, an optimal balance of speed and accuracy can also be considered by the responder on the basis of the priorities of the current situation. The mutual dependence of RT and accuracy is evident when more emphasis on accuracy results in increases in RTs and when, conversely, more emphasis on speed (i.e., shorter RTs) causes accuracy to decrease. As was noted by Wickelgren (1977), the study of RTs in conjunction with accuracy (i.e., the whole speed-accuracy trade-off [SAT] function) has the potential to provide much greater knowledge about information processing dynamics than can the study of either the RT or accuracy aspects of performance separately.

Switching between tasks results in costs in terms of both RT and accuracy (Monsell, 2003). A review of the influential studies in the task-switching area reveals that the issue of SATs and how corresponding speed-accuracy manipulations can affect task-switching performance has rarely been directly examined. One exception is Gopher, Armony, and Greenshpan (2000), whose major interest in SATs, however, involved a comparison of the costs associated with switching between tasks and the costs associated with switching between speed and accuracy strategy emphases. Another exception is Lien, Ruthruff, Remington, and Johnston (2005), involving time deadlines, which were utilized by Lien et al. in order to provide their participants with the strongest possible motivation for optimal performance.

Studying SATs

Trading off accuracy for speed or vice versa can be expected in presumably any task. Systematic experimental work on the phenomenon began in the 1950s and '60s (for a discussion of this work, see Wickelgren, 1977). The SAT paradigm in cognitive psychology addresses the inverse relationship between speed and accuracy (or, correspondingly, the positive relation between RTs and accuracy) by examining the process of information accumulation through time. In this way, an experimenter can observe how different methods of manipulation of speed emphasis result in changes in both the RTs and the accuracy of the responses. Under speed pressure, more incorrect responses are expected, and SAT curves can be derived to specify how much time is needed to achieve a particular accuracy level. This procedure was initially used by a few researchers in the 1970s (e.g., Reed, 1973, 1976) to study cognitive processing.

One important method through which speed-accuracy performance can be explicitly manipulated is by using response signals. Within such paradigms, the participants' stimulus processing is interrupted at different times after stimulus presentation (e.g., Boldini, Russo, & Avons, 2004; Boldini, Russo, Punia, & Avons, 2007; Corbett & Wickelgren, 1978; Dosher, 1981, 1982; Göthe & Oberauer, 2008; Kumar, Rakitin, Nambisan, Habeck, & Stern, 2008; Lohman, 1986; McElree & Dosher, 1989, 1993; McElree, Plykkänen, Pickering, & Traxler, 2006; Miller, Sproesser, & Ulrich, 2008; Öztekin & McElree, 2006; Ratcliff, 2006; Reed, 1973; Schouten & Bekker, 1967). …

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