Visual indexing theory: Difference between revisions

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Revision as of 09:43, 26 June 2016

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===Spotlight and zoom-lens models of attention===

The traditional view of visual perception holds that [[attention]] is fundamental to visual processing. In terms of an analogy offered by Posner, Snyder and Davidson (1980): "Attention can be likened to a spotlight that enhances the efficiency of detection of events within its beam".<ref>Posner, M. I., Snyder, C. R. R. and Davidson, B. J. (1980). Attention and the Detection of Signals. Journal of Experimental Psychology: General, Vol. 109, No. 2, 160-174.</ref> This spotlight can be controlled volitionally, or drawn involuntarily to salient elements of a scene,<ref>Posner, M. I. (1980). Orienting of attention. Quarterly Journal of Experimental Psychology, 32, 3–25.</ref> but a key characteristic is that it can only be deployed to one object___location at a time. In 1986, Eriksen and St. James conducted a series of experiments which suggested that the spotlight of attention comes equipped with a zoom-lens. The zoom-lens allows the size of the area of attentional focus to be expanded (but due to a fixed limit on available attentional resources, only at the expense of processing efficiency).<ref>Eriksen, C. W. and St. James, J. D. (1986). Visual attention within and around the field of focal attention: A zoom lens model. Perception & Psychophysics, 40 (4), 225-240.</ref>

According to Pylyshyn, the spotlight/zoom-lens model cannot tell the complete story of visual perception. He argues that a pre-attentive mechanism is needed to individuate objects upon which a spotlight of attention could be directed in the first place. Furthermore, results of multiple object tracking studies (discussed below) are "incompatible with the proposal that items are accessed by moving around a single spotlight of attention."<ref name="Pylyshyn94"/> Visual indexing theory addresses these limitations.