The flexible focus: Whether spatial attention is unitary or divided depends on observer goals.

Abstract

The distribution of visual attention has been the topic of much investigation, and various theories have posited that attention is allocated either as a single unitary focus or as multiple independent foci. In the present experiment, we demonstrate that attention can be flexibly deployed as either a unitary or a divided focus in the same experimental task, depending on the observer's goals. To assess the distribution of attention, we employed a dual-stream Attentional Blink (AB) paradigm and two target pairs. One component of the AB, Lag-1 sparing, occurs only if the second target pair appears within the focus of attention. By varying whether the first-target-pair could be expected in a predictable location (always in-stream) or not (unpredictably in-stream or between-streams), observers were encouraged to deploy a divided or a unitary focus, respectively. When the second-target-pair appeared between the streams, Lag-1 sparing occurred for the Unpredictable group (consistent with a unitary focus) but not for the Predictable group (consistent with a divided focus). Thus, diametrically different outcomes occurred for physically identical displays, depending on the expectations of the observer about where spatial attention would be required. The Flexible Focus 3Stimuli presented at attended locations are processed faster and more accurately than those presented at unattended locations (LaBerge, 1995). Theories to account for this benefit typically appeal to either (a) a single unitary focus of attention that expands and contracts so as to optimize performance on the task at hand (e.g., Barriopedro & Botella, 1998;Castiello & Umiltà, 1990 Eriksen & St. James, 1986;Eriksen & Yeh, 1985;Heinze et al., 1994;Jans, Peters, & De Weerd, 2010;Jonides, 1983), or (b) multiple foci deployed to different locations simultaneously (e.g., Awh & Pashler, 2000;Cave, Bush, & Taylor, 2010; Kawahara & Yamada, 2007;McMains & Somers, 2004, 2005Müller et al., 2003). Here we demonstrate that focused attention can be flexibly deployed in either a unitary or a divided mode. Specifically, our goal was to show that both modes of attentional deployment can occur when viewing the same stimulus displays, and that whether spatial attention is unitary or divided will depend on the expectations of the observer.To allow both types of attentional deployment to be assessed with the same experimental procedure, we modified two well-established behavioral measures of attention: the attentional blink and Lag-1 sparing. The attentional blink (AB) refers to the impaired identification of the second of two rapidly-sequential targets (T1, T2). This deficit is most pronounced at short inter-target lags, and vanishes at lags beyond about 500 ms (Chun & Potter, 1995;Raymond, Shapiro, & Arnell, 1992).Lag-1 sparing refers to the somewhat paradoxical finding that identification of the second target is unimpaired when it appears directly after the first target in the same spatial location (Potter, Chun, Banks, & Muckenhoupt, 1998;Visser et al., 1999). It is...

Working memory capacity accounts for the ability to switch between object-based and location-based allocation of visual attention

“…More specifically, they extend this literature by demonstrating that when a given situation would benefit from object-based visual attention, only those with the available cognitive resources-such as WMC-will use object-based attention. Moreover, recent research has suggested that people can also attend multiple independent locations at a time (Jefferies et al, 2014). These findings suggest that high-and low-spans should differ in this ability, as well.…”

“…The highest resolution of attention then comes from information closest to the center of the spotlight of attention, with lower resolution of attention farther from the center (Arrington, Carr, Mayer, & Rao, 2000;LaBerge, 1983;LaBerge & Brown, 1989;Posner, Snyder, & Davidson, 1980). However, others argue that cued visual attention does not work as a spotlight, and is instead based on expectations of the appearance within a shape or object-such as a square or a ring (Bleckley et al, 2003;Egly & Homa, 1984;Jefferies, Enns, & Di Lollo, 2014;Neisser & Becklen, 1975).…”

Right visual-field advantage in the attentional blink: Asymmetry in attentional gating across time and space

“…The experiment was 1 Several recent studies did demonstrate Lag-1 sparing when T1 and T2 were presented in two different RSVP streams (Jefferies & Di Lollo, 2009;Jefferies, Enns, & Di Lollo, 2014;Jefferies, Ghorashi, Kawahara, & Di Lollo, 2007;Potter, Staub, & O'Connor, 2002;Shih, 2000). However, Jefferies and colleagues suggested that participants' attention was spread across the two streams, leading the two streams to be processed as one location.…”

Mapping the spatiotemporal dynamics of interference between two visual targets

“…Duncan et al (1994) presented two masked targets at different spatiotemporal offsets and observed what they termed an attentional dwell time, which resembles in many ways an attentional blink, except that the targets were presented approximately 2-4 degrees apart and without RSVP. Many other experiments have demonstrated variations of the attentional blink across different locations for targets presented either in isolation, or in ongoing RSVP streams with spatial separations ranging from .5 to 9 degrees of visual angle (Bay & Wyble, 2014;Du, Abrams, & Zhang, 2011;Jefferies & Di Lollo, 2009;Jefferies, Enns, & Di Lollo, 2014;Kawahara & Yamada, 2006;Jefferies, Ghorashi, Kawahara, & Di Lollo, 2007;Kristjánsson & Nakayama, 2002;Shih, 2000;Visser, Bischof, & Di Lollo, 1999).…”