The Differing Impact of Multisensory and Unisensory Integration on Behavior

TLDR

Pooling and synthesizing signals across different senses often enhances responses to the event from which they are derived, and cross‑modal signals provide statistically independent samples that can reduce error more than within‑modal signals. The study investigates whether multisensory response enhancements arise from simple target redundancy or from a special quality inherent in combining cues from different senses. The authors tested this by measuring animals’ localization and detection performance for visual, auditory, visual‑auditory, visual‑visual, and auditory‑auditory stimuli presented individually or in cross‑modal and within‑modal combinations. They found that performance enhancements were far greater for cross‑modal than for within‑modal combinations, supporting the idea that multisensory integration yields benefits beyond simple target redundancy.

Abstract

Pooling and synthesizing signals across different senses often enhances responses to the event from which they are derived. Here, we examine whether multisensory response enhancements are attributable to a redundant target effect (two stimuli rather than one) or if there is some special quality inherent in the combination of cues from different senses. To test these possibilities, the performance of animals in localizing and detecting spatiotemporally concordant visual and auditory stimuli was examined when these stimuli were presented individually (visual or auditory) or in cross-modal (visual-auditory) and within-modal (visual-visual, auditory-auditory) combinations. Performance enhancements proved to be far greater for combinations of cross-modal than within-modal stimuli and support the idea that the behavioral products derived from multisensory integration are not attributable to simple target redundancy. One likely explanation is that whereas cross-modal signals offer statistically independent samples of the environment, within-modal signals can exhibit substantial covariance, and consequently multisensory integration can yield more substantial error reduction than unisensory integration.