Academic journal article North American Journal of Psychology

Performance on Speeded Working Memory Recognition Is Not Mediated by Duration on a Distractor Task Following an Attention Shift

Academic journal article North American Journal of Psychology

Performance on Speeded Working Memory Recognition Is Not Mediated by Duration on a Distractor Task Following an Attention Shift

Article excerpt

This study investigated the role of brief stimulus presentation times and attention shifting on retrieval from working memory. Participants were given brief or long presentation times to encode a four-word list, which was followed by a task requiring a same-or different decision, which was then followed by a recognition memory task. Consistent with our expectations, when the presentation times were brief, participants required additional time to make the following same-different decision than when presentation times were long. Also, when the presentation times were brief, the participants had poorer recognition for the working memory elements than when presentation times long. However, these effects were not mediated by the participant's duration on the same-different task: The variance in recognition memory effects was accounted for by the presentation time differences, and not by duration differences on the same-different task. Our findings are interpreted both in terms of the generality of the limits of capacity and processing in working memory and the operation of a central executive that coordinates attentional shift.

According to Baddeley's model of working memory (Baddeley, 1986, 1996, 2000) to-be-remembered items are maintained and processed by several domain-specific buffers (e.g., verbal, visual-spatial, episodic buffer, and perhaps others) whose activity is coordinated by a central executive that allocates attentional capacity among various sources of stimulation, determines the timing and direction of attentional shifts, and activates representations in permanent memory. Although the capabilities of the central executive have not been completely specified, some findings (e.g., Duff & Logie, 2001) suggest that if the system's goals do not include remembering the incoming stimuli, then the central executive may process the information without encoding it into any particular working memory buffer. This theoretical account of the central executive's role helps explain some aspects of consecutive-tasks performance, a situation in which a participant must shift attention to process two consecutively presented sources of stimulation.

For example, Woodman, Vogel, and Luck (2001) had their participants preload various numbers of stimuli, up to capacity, into visual working memory. Following this preloading, participants performed a visual search task. As expected, participants required more time to do the visual search task when their visual working memories had been preloaded, compared to when they had not. However, the delay in performance produced by the visual working memory was basically constant, and therefore not affected by the amount of the working memory load. Moreover, Woodman et al. found that the search task per se did not dramatically impair the retrieval process from visual working memory. They interpreted these findings to mean that the efficiency of the search process is not impaired when visual working memory is loaded to capacity. Presumably the activities of the central executive, which include allocating attention to the search process, do not include automatically loading the contents of the visual search into visual working memory. Thus, these findings imply that cognitive activity occurring after attention shifts has little or no effect on maintenance of material in visual working memory. Other studies have corroborated these effects and extended them. For example, Han and Kim (2004) theorized that while the executive functions of working memory, including attention, are not necessarily used to simply keep material resident in working memory, it could well be the case that the executive function is actively being used while stimuli are being manipulated in memory. That leads to the expectation that a visual search task would be affected by a working memory manipulation, if working memory and attention are related to each other. In support of this position, they found that when participants were required only to maintain verbal items in working memory, visual search efficiency was unaffected by the preloading (compared to a search alone condition), which is very similar to the results of Woodman et al. …

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