Academic journal article Attention, Perception and Psychophysics

Mapping the Spatiotemporal Dynamics of Interference between Two Visual Targets

Academic journal article Attention, Perception and Psychophysics

Mapping the Spatiotemporal Dynamics of Interference between Two Visual Targets

Article excerpt

Published online: 13 June 2015

© The Psychonomic Society, Inc. 2015

Abstract A major thread of visual cognition has been to explore the characteristics of the attention system by presenting two targets and observing how well they can both be reported as a function of their temporal and spatial separation. This method has illuminated effects such as the attentional blink, the attentional dwell time, competitive interference, sparing temporal order errors, and localized attentional interference. However, these different effects are typically explored separately, using quite distinct experimental paradigms. In an effort to consolidate our understanding of these various effects into a more comprehensive theory of attention, we present a new method for measuring spatial gradients of interference at different temporal separations between two targets without creating specific expectations about target location. The observed data support theories that there are multiple sources of interference within the visual system. A theoretical model is proposed that illustrates how three distinct forms of interference could arise through the processes of identifying, attending, and encoding visual targets.

Keywords Visual Attention . Neural Mechanisms . Competitive Interference . Attentional blink . Retroactive Interference

Introduction

When faced with an overabundance of information, the visual system uses attention to select important stimuli to be perceived. Without this ability to focus on specific stimuli, the processing capabilities of the brain would be incapable of taking the prompt, decisive action that is required for navigating a complex environment in real time. Visual attention is a complex phenomenon that is almost certain to result from a variety of tightly coupled mechanisms within the visual system. To discover these mechanisms, there has been much interest in charting the temporal and spatial fluctuations of attention in response to a task relevant stimulus. One of the more effective techniques for doing this has been to present two stimuli in sequence where the second stimulus acts as a probe of the state of attention at varying spatial or temporal offsets from the first (Broadbent & Broadbent, 1987). This method has discovered and characterized such phenomena as the attentional blink, in which two targets (T1 and T2) are presented in a rapid serial visual presentation (RSVP) at one location, resulting in a dramatic reduction in the ability to report the T2 when it occurs about 300 ms after the T1 (Raymond, Shapiro,&Arnell, 1992). There are other findings of inter-target interference in the literature, including the attentional dwell time (Duncan, Ward, & Shapiro, 1994), competitive interference (Potter, Staub, & O'Connor, 2002), temporal order errors (Bowman & Wyble, 2007; Chun & Potter, 1995; Hommel & Akyürek, 2005; Olivers, Hilkenmeier, & Scharlau, 2011) and localized attentional interference (Mounts, 2000). Each of these effects describes a particular change in the ability to accurately report two targets as a function of their temporal or spatial separation.

However, it is often unclear whether these effects are distinct manifestations of a common interference process or whether they reflect distinct mechanisms. This uncertainty stems from the fact that different phenomena are studied using different methods. For example, localized attentional interference typically varies spatial offset while holding temporal separation constant, and studies of the attentional blink typically use converse methods. While such highly precise experimental control is an essential tool for studying the human visual system, the use of distinct paradigms to study distinct effects impedes our progress towards a comprehensive understanding of attention for two reasons. First, the visual attention system is known to be highly configurable according to task demands, such as attentional set when using blocked designs (Belopolsky, Schreij, & Theeuwes, 2010; Folk, Remington, & Johnston, 1992), and thus the visual system may be adapting to the tasks that are being used to study it. …

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