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Neuropsychologia. 2016 Jul 29;88:83-91. doi: 10.1016/j.neuropsychologia.2016.01.031. Epub 2016 Jan 27.

Interactions between space and effectiveness in human multisensory performance.

Author information

1
Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, United States. Electronic address: aaron.r.nidiffer@vanderbilt.edu.
2
Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, United States; Vanderbilt Brain Institute, United States; Vanderbilt University Kennedy Center, United States; Department of Psychology, University of Toronto, United States.
3
Neuroscience Graduate Program, Vanderbilt University Medical Center, United States.
4
Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, United States; Vanderbilt University Kennedy Center, United States.
5
Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, United States; Vanderbilt Brain Institute, United States; Vanderbilt University Kennedy Center, United States; Department of Psychology, Vanderbilt University, United States; Department of Psychiatry, Vanderbilt University, United States.

Abstract

Several stimulus factors are important in multisensory integration, including the spatial and temporal relationships of the paired stimuli as well as their effectiveness. Changes in these factors have been shown to dramatically change the nature and magnitude of multisensory interactions. Typically, these factors are considered in isolation, although there is a growing appreciation for the fact that they are likely to be strongly interrelated. Here, we examined interactions between two of these factors - spatial location and effectiveness - in dictating performance in the localization of an audiovisual target. A psychophysical experiment was conducted in which participants reported the perceived location of visual flashes and auditory noise bursts presented alone and in combination. Stimuli were presented at four spatial locations relative to fixation (0°, 30°, 60°, 90°) and at two intensity levels (high, low). Multisensory combinations were always spatially coincident and of the matching intensity (high-high or low-low). In responding to visual stimuli alone, localization accuracy decreased and response times (RTs) increased as stimuli were presented at more eccentric locations. In responding to auditory stimuli, performance was poorest at the 30° and 60° locations. For both visual and auditory stimuli, accuracy was greater and RTs were faster for more intense stimuli. For responses to visual-auditory stimulus combinations, performance enhancements were found at locations in which the unisensory performance was lowest, results concordant with the concept of inverse effectiveness. RTs for these multisensory presentations frequently violated race-model predictions, implying integration of these inputs, and a significant location-by-intensity interaction was observed. Performance gains under multisensory conditions were larger as stimuli were positioned at more peripheral locations, and this increase was most pronounced for the low-intensity conditions. These results provide strong support that the effects of stimulus location and effectiveness on multisensory integration are interdependent, with both contributing to the overall effectiveness of the stimuli in driving the resultant multisensory response.

KEYWORDS:

Localization; Multisensory; Psychophysics; Race model

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