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David Brang, Satoru Suzuki, Marcia Grabowecky; Multisensory redundancy gain partially mediated by stimulus detectability. Journal of Vision 2013;13(9):882. doi: 10.1167/13.9.882.
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© ARVO (1962-2015); The Authors (2016-present)
The redundant-target effect is a basic and well-replicated finding that participants respond faster to a multisensory target (a combined sound and light) than to a unisensory target (an isolated sound or light). This response speeding is generally attributed to superadditive effects at the level of individual neurons, such that the neural response to a multisensory stimulus is greater than would be predicted from separate responses to the individual unisensory stimuli. However, a multisensory stimulus presentation also enhances the detectability of its unisensory components. Here we investigated whether multisensory facilitation is mediated by crossmodal enhancements of unisensory components rather than or in addition to the integration of multisensory signals. To test this hypothesis, visual detection thresholds were estimated using a 2AFC staircase procedure for a brief visual flash (visual alone condition) and a flash paired with a synchronous auditory tone (auditory-visual condition). Replicating prior work, significantly lower detection thresholds were observed for visual targets paired with an auditory cue relative to visual targets alone (p=.02). These thresholds were then used in a subsequent go-no-go redundant-target task in which subjects responded to target stimuli in four conditions: (1) auditory-target alone, (2) visual-target alone at 120% visual alone contrast threshold, (3) auditory-visual target at 120% visual-alone contrast threshold, and (4) auditory-visual target at 120% auditory-visual contrast threshold. Conditions 2 and 3 presented flashes of equal contrast. The auditory-visual condition 4, however, presented physically dimmer but equally detectable flashes to those of the visual alone condition (controlling for auditory effects on visual salience). Auditory-visual stimuli in condition 3 were responded to faster than visual or auditory targets alone, but this benefit was significantly reduced for auditory-visual stimuli equated for visual detectability (condition 4; p=.01) suggesting that the redundant-target effect is partly driven by auditory enhancement of visual salience in addition to multisensory integration.
Meeting abstract presented at VSS 2013
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