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Pi-Chun Huang, Yi-Chuan Chen; Human sensory dominance is modulated by stimulus temporal uncertainty rather than by spatial uncertainty. Journal of Vision 2019;19(10):20. doi: https://doi.org/10.1167/19.10.20.
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When it comes to detecting or identifying sensory signals, vision is typically the dominant modality over audition. One classic example is the Colavita visual dominant effect: The presentation of a beep sometimes goes undetected when it is paired with a flash, even though each stimulus is well detected when presented alone. Visual dominance effect is suggested to be attributed to the fact that the majority of the cerebral cortex is recruited for visual processing; nevertheless, attending to audition can help balance such a natural bias. Here we investigated whether visual dominance effect can be modulated by stimulus uncertainty in the temporal and spatial domain, respectively. In Experiment 1, a visual target (a 1-degree disc), an auditory target (a 1000-Hz pure tone burst), or a bimodal target (the combination of the above two) was presented with equal probability. Participants had to press a key when detecting the visual target, another key when detecting the auditory target, and both keys when detecting the bimodal target. The classic visual dominance effect was replicated so that the participants made visual-only responses more often than auditory-only responses on the bimodal trials. In Experiment 2, we enlarged the temporal uncertainty of targets by increasing the inter-stimulus interval (ISI) in 25% of the trials (mean ISI: 200 vs. 1700 ms). To increase spatial uncertainty in Experiment 3, the flash was presented either in the center or 4 degrees above or below the center in 25% of the trials. The visual dominance effect was eliminated when increasing temporal uncertainty, whereas it remained significant when increasing spatial uncertainty. We therefore demonstrate a novel factor that temporal uncertainty reduced the dominance of vision over audition, suggesting that people’s sensory dominance is context dependent. Our result also implies a modality-appropriate view that visual dominance most likely occurs in a spatial-related task.
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