Academic journal article Perception and Psychophysics

Attentional Selection: A Salience-Based Competition for Representation

Academic journal article Perception and Psychophysics

Attentional Selection: A Salience-Based Competition for Representation

Article excerpt

The role of salience in localized attentional interference (LAI) was examined. In two experiments, target discrimination performance was measured as a function of the spatial separation between the target and a salient distractor item. In Experiment 1, both the salience of the distractor and that of a target were manipulated. Distractor salience was manipulated via size changes to the distractor, and target salience was manipulated by using unmasked or onset targets. When the target was of low salience, the magnitude of interference from the distractor increased with distractor salience. However, when the target had an abrupt onset, the distractor had no impact on target performance. In Experiment 2, the attentional salience of the distractor was manipulated using a probability manipulation. Displays contained both a target and a color singleton distractor. The color singleton produced LAI when it was predictive of the target location but not when it was unpredictive of the target location. The results of both experiments are consistent with models of competition-based attentional selection.

Several recent models of visual selective attention propose that attentional selection of an object or region results from a competition among objects for representation within the visual system. These include the model of Deco and Rolls (2004), Cave's (2001) feature gate model, Desimone and Duncan's (1995) biased competition model, and Tsotsos's (e.g., Tsotsos et al., 1995) selective tuning model. These models propose that objects compete for control of visually selective neurons and that the response of a given neuron will represent the properties of only the "winning" object.

Given the architecture of the primate visual system, this competition between two objects should depend on their relative locations in the visual field, among other things. According to Desimone and Duncan's ( 1995) biased competition model of attention, for example, objects compete with one another for representation at various levels within the visual system. Desimone (1998) points out that this competition should be strongest among objects competing for representation by the same populations of neurons. In general, the proportion of receptive fields shared by a pair of objects will increase with increased spatial proximity; therefore, the degree of competition between objects should increase with decreased spatial separation. Likewise, in the model of Deco and Rolls (2004), Tsotsos et al.'s (1995) selective tuning model, and Cave's (2001) feature gate model, all of which employ a space-based hierarchical pyramid architecture, the extent to which two objects can be processed before coming into competition with one another depends on their spatial separation. Objects with greater spatial separation are processed in parallel through higher levels in the hierarchy before coming into competition with one another.

Several recent behavioral studies have provided evidence of such a spatially dependent competition among objects. For example, shape discriminations (see, e.g., Mounts, 200Oa, 200Ob; Mounts & Tomaselli, 2005; Turatto & Galfano, 2001) and line length judgments (Caputo & Guerra, 1998) have been shown to be slower and less accurate when target stimuli appear near attentionally salient distractors such as color singletons. When observers are asked to identify two targets, their accuracy in identifying both targets improves with increased separation between the targets (see, e.g., Bahcall & Kowler, 1999). Similarly, when observers are asked to make samedifferent judgments, they become faster and more accurate with increased separation between the two targets (Cutzu & Tsotsos, 2003; McCarley, Mounts, & Kramer, 2004). All of these studies suggest that competition between attentionally salient objects occurs when they are spatially proximal and that this competition declines with increased spatial separation. This localized attentional interference (LAI) is consistent with the notions that spatially proximal stimuli may be competing for common pools of neural resources and that increasing the spatial separation between objects allows them to be represented by increasingly independent populations of neurons. …

Search by... Author
Show... All Results Primary Sources Peer-reviewed

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.