Touch-induced Visual Illusion
Poster Presentation

Artem Violentyev
Psychology Dept., University of California Los Angeles

Shinsuke Shimojo
Division of Biology, California Institute of Technology

Ladan Shams
Psychology Dept., University of California Los Angeles

     Abstract ID Number: 76
     Full text: Not available
     Last modified: March 18, 2005

Abstract
Although vision is considered the dominant modality, recent studies demonstrate the influence of other modalities on visual perception. We report an original illusion demonstrating a significant change in visual perception due to task irrelevant tactile stimulation, what we call the “touch-induced flash illusion.” Methods: Subjects reported the number of peripheral visual stimuli while ignoring tactile stimulation, provided by a refreshable Braille cell to the tip of the left index finger. A factorial design was used with two factors: the number of flashes (1 or 2), and number of taps (0, 1, 2). Thirty trials of each condition were presented in random order to nine naïve subjects. Results: On average, observers reported seeing two flashes on 62.6% of trials when a single flash was accompanied by two taps, compared to 20.7% of trials when it was presented in the absence of taps. Furthermore, signal detection theory analysis indicated that double taps caused a change in sensitivity in visual discrimination. This radical change in perception was consistent across all subjects tested. Conclusion: These findings provide further evidence challenging the notion that visual perception is independent of activity in other modalities.