Academic journal article Memory & Cognition

Overt Is No Better Than Covert When Rehearsing Visuo-Spatial Information in Working Memory

Academic journal article Memory & Cognition

Overt Is No Better Than Covert When Rehearsing Visuo-Spatial Information in Working Memory

Article excerpt

Published online: 20 July 2011

© The Author(s) 2011. This article is published with open access at Springerlink.com

Abstract In the present study, we examined whether eye movements facilitate retention of visuo-spatial information in working memory. In two experiments, participants memorised the sequence of the spatial locations of six digits across a retention interval. In some conditions, participants were free to move their eyes during the retention interval, but in others they either were required to remain fixated or were instructed to move their eyes exclusively to a selection of the memorised locations. Memory performance was no better when participants were free to move their eyes during the memory interval than when they fixated a single location. Furthermore, the results demonstrated a primacy effect in the eye movement behaviour that corresponded with the memory performance. We conclude that overt eye movements do not provide a benefit over covert attention for rehearsing visuo-spatial information in working memory.

Keywords Attention . Eye movements .Working memory

Several lines of research have shown that spatial selection mechanisms are involved in maintaining visuo-spatial information in working memory (e.g., Awh, Anllo-Vento, & Hillyard 2000; Awh, Jonides, & Reuter-Lorenz 1998; Awh et al., 1999; Lawrence, Myerson, & Abrams 2004; Smyth & Scholey, 1994; Tremblay, Saint-Aubin, & Jalbert 2006). It has been suggested that covert shifts of attention or overt movements of the eyes function as a rehearsal mechanism within visuo-spatial working memory (e.g., Awh & Jonides, 2001; Tremblay et al., 2006). In fact, Baddeley (1986) already suggested such a role for the oculomotor system, analogous to the articulatory rehearsal of verbal material. However, even without the execution of eye movements, observers can select the memorised locations through the allocation of covert attention. Indeed, it is yet unclear whether eye movements provide any benefit for visuo-spatial working memory relative to covert attention. Even though there is a strong relationship between covert attention and eye movements (e.g., Deubel & Schneider, 1996; Hoffman & Subramaniam, 1995; Kowler, Anderson, Dosher, & Blaser 1995; Rizzolatti, Riggio, & Sheliga 1987), in some circumstances these mechanisms are dissociated (Belopolsky & Theeuwes, 2009), and therefore it is feasible that they have different effects on working memory.

The view that covert attention is a rehearsal mechanism that allows spatial information to be maintained in working memory gained support from a study by Smyth and Scholey (1994). In their study, participants performed a Corsi block task, which required them to remember the order in which the stimuli had been presented. It was found that secondary tasks requiring attention shifts performed during the retention interval impaired recall in this task (see also Smyth, 1996). This indicated that covert attention to the stimulus location was required during the retention interval to keep that location in working memory. Further evidence for a role of covert attention was provided by Awh, Jonides, and Reuter-Lorenz (1998), who found enhanced visual processing at locations that were held in working memory, suggesting that covert attention was directed at these to-be-remembered locations. Also, neural imaging and ERP studies of working memory tasks have demonstrated neural activity patterns (Awh et al., 1999, 2000; Jha, 2002) that were similar to the effects of covert attention.

In contrast to the covert attentional rehearsal view, Tremblay et al. (2006) have argued that rehearsal of visuo-spatial information is achieved by eye movements. This oculomotor rehearsal hypothesis is consistent with several lines of research that have pointed to some sort of relationship between memory and eye movements. Several studies have shown that participants regularly look at the previous location of a cued object, even if this location has become empty (e. …

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