Tactile-auditory saltation: spatiotemporal integration across sensory modalities.

The perceptual phenomena of sensory saltation involve the systematic displacement of a target stimulus (the attractee) towards a subsequent stimulus (the attractant), which occurs closely in time and space. Here, we demonstrate the existence of cross-modal tactile-auditory saltation. Tactile stimuli were delivered to the forehead and spatially congruent stereoscopic auditory stimuli were presented via headphones to a total of 20 participants. After a reference stimulus at one of five spatial positions, the attractee was presented at a fixed position, followed by the attractant at a different fixed position with a delay of 81, 121, or 181 ms. Participants rated whether the attractee was perceived left or right of the reference in 2 uni-modal and 2 cross-modal (different reference/attractee vs. attractant mode) configurations. Saltation was present in all uni- and cross-modal configurations at an attractee-attractant delay of 81 ms. At delays of 81 ms the overall displacements were stronger than at delays of 121 ms, and tactile attractants generally induced stronger displacements than auditory attractants. The results indicated the existence of cross-modal tactile-auditory saltation, suggesting the application of the saltation phenomenon as a powerful approach for examining multi-modal sensory representations in future studies.