Splitting Visual Focal Attention? It Probably Depends on Who You Are

Splitting Visual Focal Attention? It Probably Depends on Who You Are Jit Yong Yap (yapjityong@gmail.com) Department of Psychology, National University of Singapore 9 Arts Link, Singapore 117570 Stephen Wee Hun Lim (psylimwh@nus.edu.sg) Department of Psychology, National University of Singapore 9 Arts Link, Singapore 117570 Abstract Research evidence now suggests that the deployment of multiple attentional foci in non-contiguous locations (i.e., splitting visual focal attention) is possible under some circumstances. However, the exact circumstances under which focal attention might ‘split’ have not been well understood. The present study is the first in the literature to examine the possibility that ecological differences arising from our increasingly media-saturated environment may result in individual differences in the capacity to demonstrate splitting focal attention. Results suggest a significant relationship between the behavioural preference for consuming multiple media forms simultaneously and the capacity to employ a split mode of attention. Keywords: Ecological differences; splitting focal attention; media multitasking Introduction In visual attention research, whether the focus of attention can be divided is an issue of debate. Several authors espouse the view that the focus of attention is unitary and indivisible in nature (e.g. Eriksen & Yeh, 1985; McCormick & Klein, 1990; Pan & Eriksen, 1993). In order to account for the processing of multiple visual stimuli in different spatial locations, two different theories have been proposed. The serial shifting theory of attention suggests that the focus of attention rapidly shifts between different locations (Eriksen & Eriksen, 1974; Posner, 1980), whereas the zoom lens theory of attention suggests that the focus of attention is adjusted in size to accommodate multiple locations (Eriksen & St. James, 1986). However, there is a growing body of evidence which supports the possibility of split attentional foci, or allocation of attention to noncontiguous regions (for review, see Jans, Peters, & De Weerd, 2010; cf. Cave, Bush & Taylor, 2010). For instance, Awh and Pashler (2000) presented participants with a 5 x 5 stimulus array and tasked them with identifying two targets following the onset of cues (validity = 80%). Results showed a strong accuracy advantage at cued locations that did not apply to targets appearing between cued locations, which suggest a divided focus of attention. In their appraisal of the current literature, Cave, Bush and Taylor (2010) concluded “the weight of evidence suggests that some form of split attention is possible in some circumstances”. With the focus on establishing the possibility of split attention, there has been little research into the exact circumstances under which split attention might arise. This was the crux of a recent study by Lim and Lee (2011), who hypothesized that adoption of a unitary or split mode of attention could be a strategic choice made by the visual system, depending on whichever was the least effortful means of extracting target information from a particular visual presentation. To test this, Lim and Lee employed a modified version of the paradigm used in McCormick, Klein and Johnston (1998). In the double cue condition of the original study, boxes 10° to the left and right of a central fixation point were used to cue the subsequent onset of a target dot. The target could appear inside either box, or between a box and the central fixation. Participants were tasked with responding to the target once it appeared in their visual field. Results showed that reaction times (RTs) for targets in cued locations (i.e. in boxes) did not differ from those that appeared in irrelevant locations (i.e. outside boxes), which was interpreted as indicative of a unitary mode of attention (See Figure 1). For their modified version of the double cue condition, Lim and Lee introduced a vertical wall positioned in the centre of the visual display with the intent of preventing a single locus of attention from encompassing both boxes. It was believed that this would incentivize a split mode of attention and, in contrast with McCormick et al. (1998), give rise to RTs for targets in irrelevant locations that were Figure 1. Predicted result trends, depending on mode of attention employed in double cue condition (McCormick et al., 1998).