Poster F120, Tuesday, March 28, 8:00 – 10:00 am, Pacific Concourse
Startling Sounds Presented under Dark Adaptation Evoke Synesthetic Experiences
Anupama Nair1,2, David Brang1; 1University of Michigan, 2University of Amsterdam
Synesthesia is a perceptual phenomenon in which stimulation of one sensory modality evokes additional experiences in an unrelated modality (e.g., sounds evoking colors), thought to arise from increased connectivity between associated sensory areas. However, non-synesthetes can experience these sensations via hallucinogenics or as the result of brain damage, raising the possibility that synesthesia exists as a latent feature in all individuals, manifesting only when the balance of activity across the senses has been altered. Indeed, multisensory connections exist in all individuals that support the processing of dynamic auditory, visual, and tactile information present in the environment, but it is thought that inhibition of these pathways and the presence of dominant bottom-up information prevents normal multisensory interactions from evoking the subjective experience of synesthesia. In this study, we sought to counter these two features of normal sensory perception in order to evoke auditory-visual synesthetic experiences in non-synesthetes. First, participants were placed in a visually deprived environment while sounds were presented from two spatial locations at random and infrequent intervals. Visual percepts evoked by startling sounds were observed in 5 out of 20 subjects. Next, we added a visual-imagery task to increase top-down feedback to early visual areas, resulting in 14 out of 24 subjects experiencing auditory-visual synesthetic percepts. Across both experiments subjects reported seeing visual images (vivid colors and Klüver's form-constants) localized to the speaker position. These results indicate a higher prevalence of synesthetic experiences in the general population and a link to normal multisensory processes.
Topic Area: PERCEPTION & ACTION: Multisensory