Academic journal article Memory & Cognition

Individual Differences in Multiple Types of Shifting Attention

Academic journal article Memory & Cognition

Individual Differences in Multiple Types of Shifting Attention

Article excerpt

Many researchers consider costs in shifting attention and mental set to reflect a basic ability to use top-down goal information to guide action. Although switch costs have been used as measures of individuals' executive function, whether common abilities underlie task set switching across different types of shifting tasks has not been well studied. In 249 participante, we studied whether switch costs in a novel two-choice reaction time task were correlated across variations in two variables: the locus of representation (stimuli were either perceptually available or stored in working memory [WM]) and which of two judgment tasks was performed. Switch costs were asymmetrical, in that it was easier to switch to the easier judgment, and were related to overall and relative processing speed: Switch costs were higher when the task was more difficult These factors should be accounted for when one is measuring individual differences in switch costs. After controlling for these effects, we found evidence for a common ability underlying switch costs that involved both task set preparation and response selection; however, residual shift costs, which involve only response selection, were uncorrelated across tasks. Correlations among switch costs were substantially higher within task type (e.g., correlations of WM shifting tasks with other WM shifting tasks and of perceptual tasks with perceptual ones), suggesting that there are also processes unique to switching within WM and switching among visible stimuli.

A number of research articles in recent years have focused on the reaction time (RT) costs incurred when previously irrelevant information-generally, stimuli, stimulus attributes (dimensions), or responses-become relevant due to changing task demands (e.g., Caravan, 1998; Gopher, Armony, & Greenshpan, 2000; Hsieh & Allport, 1994; Meiran, Chorev, & Sapir, 2000; Monsell, Yeung, & Azuma, 2000; Rogers & Monsell, 1995; Rubinstein, Meyer, & Evans, 2001; Shafiullah & Monsell, 1999; Yeung & Monsell, 2003a). These are generally called task-switching paradigms, and they are thought to measure the ability to rapidly reconfigure perceptual and response sets to match changing environmental demands. Because a hallmark of such tasks is that they require flexible, context-dependent goal setting and execution, they may be useful as measures of a fundamental type of cognitive control (e.g., Baddeley, 1992; Hitch & Baddeley, 1976; Miller & Cohen, 2001; Norman & Shallice, 1986).

In a typical switching task, one is asked to respond to one of two or more attributes of a stimulus by making a speeded response. For instance, one might see the number/letter pair "5A" and be asked, on one trial, to judge whether the number is even or odd (Rogers & Monsell, 1995). On the next trial, one may see a new stimulus ("3C") and be asked to make a vowel/consonant judgment on the letter (a switch trial) or to make the same odd/even judgment (a no-switch trial). The increase in average RT on switch trials, in comparison with no-switch trials, is the most common measure of switch costs.

Although the switching of attention demanded by these tasks is often referred to as an executive process (Garavan, Ross, Li, & Stein, 2000; Gopher, 1996; Kimberg, Aguirre, & D'Esposito, 2000; Miyake et al., 2000; Rubinstein et al., 2001 ; Sylvester et al., 2003), there has been debate about what types of mental processes switch costs reflect. According to one view, switch costs are likely to be related, at least in part, to the time it takes to retrieve previously inactive task rules and goals from long-term memory (Mayr & Kliegl, 2000; Rogers & Monsell, 1995; Spector & Biederman, 1976). According to a second view, previously performed but currently irrelevant tasks continue to capture attention, prime task goals, or both, and switch costs reflect the time it takes to resolve interference from competing task sets (Allport, Styles, & Hsieh, 1994). …

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