A Limiting Channel Capacity of Visual Perception: Spreading Attention Divides the Rates of Perceptual Processes
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A Limiting Channel Capacity of Visual Perception: Spreading Attention Divides the Rates of Perceptual Processes Joseph S. Lappin 1,2 & Adriane E. Seiffert 1 & Herbert H. Bell 2
# The Psychonomic Society, Inc. 2020
Abstract This study investigated effects of divided attention on the temporal processes of perception. During continuous watch periods, observers responded to sudden changes in the color or direction of any one of a set of moving objects. The set size of moving objects was a primary variable. A simple detection task required responses to any display change, and a selective task required responses to a subset of the changes. Detection rates at successive points in time were measured by response time (RT) hazard functions. The principal finding was that increasing the set size divided the detection rates—and these divisive effects were essentially constant over time and over the time-varying influence of the target signals and response tasks. The set size, visual target signal, and response task exerted mutually invariant influence on detection rates at given times, indicating independent joint contributions of parallel component processes. The lawful structure of these effects was measured by RT hazard functions but not by RTs as such. The results generalized the time-invariant divisive effects of set size on visual process rates found by Lappin, Morse, & Seiffert (Attention, Perception, & Psychophysics, 78, 2469–2493, 2016). These findings suggest that the rate of visual perception has a limiting channel capacity. Keywords Attention: Divided Attention and Inattention . Attention: Theoretical and Computational Models . Reaction time methods . Hazard functions . Process rates . Channel capacity
Introduction We know less than meets the eye. Visual processes convert variations in optical energy into information, but potential information is often not consciously perceived. When attention is distributed over multiple objects and events, recognition of any given object or event becomes slower and less accurate. This study examined how distributed attention affected temporal processes for detecting a target change in any one of several moving objects.
Objects and events that are entirely visible, centered in the field of view, and seemingly salient are surprisingly vulnerable to the limitations of conscious perceptual awareness.1 Indeed, failures of perceptual awareness are more common than we realize (Levin, Momen, & Drivdahl, 2000). These failures have been documented in many different everyday settings (e.g., Chabris & Simons, 2009; Drew, Vo, & Wolfe, 2013; Varakin, Levin, & Fidler, 2004; Wolfe, Soce, & Schill, 2017; Young & Regan, 2007). The limitations of awareness are also well documented in controlled experiments (e.g., Cohen, Cavanagh, Chun, & 1
* Joseph S. Lappin [email protected] 1
Vanderbilt University, Nashville, TN, USA
2
Discerning Technologies LLC, San Diego, CA, USA
Awareness is not a well-defined concept. Koenderink (2012, 2018, pp. 23– 25) offers a comprehensive description of
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