Multisensory Interplay and Theories of Consciousness

Sensory interplay typically refers to cases where the content of one sensory modality affects the content of another sensory modality. Although there is much evidence today of such interplay, it is unknown how to interpret them. Is it a one-way causal function between two separate states (e.g., a visual process that influences an auditory process), a bidirectional relation between two separate states, or a new kind of state—as a sensory integration—that cannot be reduced to interactions between separate states? Despite these questions, the first-person perspective offers the insight that sensory modalities often integrate and that conscious content is seldom composed exclusively of one sense. Here, we explore how to understand sensory interplay and integration and how this analysis may provide a tool to analyze and investigate theories of consciousness. We argue that multisensory interplay leads the way to new empirical approaches to theory comparison that are not derivable from research in single perceptual systems, which may suggest new potential avenues of progress in consciousness science.