Academic journal article Attention, Perception and Psychophysics

Coherence of Visual Representations: Attention and Integration of Contour Shape Information

Academic journal article Attention, Perception and Psychophysics

Coherence of Visual Representations: Attention and Integration of Contour Shape Information

Article excerpt

Published online: 1 My 2014

© The Psychonomic Society, Inc. 2014

Abstract Change blindness demonstrations illustrate the limited detail of visual representations. These demonstrations typically require disruption to the visual input when the change occurs or changes that occur very slowly. With sustained viewing or faster changes to the scenes, changes are more easily detected because attention can be effectively allocated to the part of the scene that is changing. Here, we investigate the interaction of visual attention and memory in the domain of 2-D contour shapes. We show, using a novel combination of established change blindness paradigms, that changes can go unnoticed even when they occur on isolated 2-D contour shapes. The effect appears to be due to involuntary updating of stored shape information. This involuntary updating process, however, is constrained so that previously attended shape information is updated only when attention is reallocated to qualitatively similar shape information.

Keywords 2D shape and form · Change blindness Attention: object-based

Attention is a critical feature of human sensory-perceptual systems that allows us to interact with the environment in an efficient way. Efficiency is important because of the mismatch between the amormt of sensory information encoded about the environment and the neural resources available to process that information. Here, we consider visual attention. A typical scene may be cluttered with objects and surfaces, each with multiple features. It is apparent from everyday experience that we do not equivalently encode and process all of the visual information that is available to the eye. Instead, the human visual system strategically allocates its resources in order to most effectively encode and process the information that is of primary behavioral relevance. Effective visual encoding and processing might involve selectively processing important objects, filtering unimportant objects, and detecting hazards.

Mechanisms of visual attention

Visual attention appears to be employed through a variety of mechanisms, each of which can direct and constrain processing in different ways. Among them, spatial allocation of attention has been, perhaps, most prominent. Spatial attention, often depicted as acting like a spotlight, enhances processing at a particular location in the visual field. A spatially based account of attention has been used to model, for example, enhanced detection of targets in the region to which attention has been deployed (e.g., Posner & Cohen, 1984) and the binding of features in visual search (Treisman & Gelade, 1980). The sophistication of our ability to allocate spatially based visual attention has, however, required elaboration of the spotlight model. For example, researchers have posited a system in which visual attention can be deployed at multiple, discrete, independent locations (Pylyshyn, 1989) to account for the ability to simultaneously track multiple objects in a scene (Pylyshyn & Storm, 1988).

Other results are less easily accounted for with any spatially based model of visual attention. For example, behavioral evidence suggests that visual attention can be directed to a specific object, even when multiple objects occupy the same part of the visual field. Vuilleumier, Schwartz, Duhoux, Dolan, and Driver (2005) showed that when subjects were presented images of two superimposed objects and were asked to attend to one of them (with the target object indicated by its color), a memory task for the unattended objects found no evidence of long-term storage (although priming suggested that some implicit processing had occurred). Similarly, Behrmann, Zemel, and Mozer (1998) used superimposed objects to show that attention could be moved more easily within perceptual obj ects than between them. An object-based account of attention is also supported by neuroimaging experiments showing that attending to one of two co-spatial objects, each of which is associated with a specialized extrastriate area (the fusiform face area and parahippocampal place area), correlates with increased neural activity in the corresponding brain region (O'Craven, Downing, & Kanswisher, 1999). …

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