Reduced audio–visual integration in synaesthetes indicated by the double-flash illusion

• Published in: Brain research Vol. 1473; pp. 78 - 86
• Main Authors: Neufeld, Janina, Sinke, Christopher, Zedler, Markus, Emrich, Hinderk M, Szycik, Gregor R
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 14.09.2012; Elsevier
• Subjects: Acoustic Stimulation; Adult; Audio–visual; Auditory Perception - physiology; Behavioral psychophysiology; Biological and medical sciences; brain; Cross-modal integration; Double-flash illusion; Ear and associated structures. Auditory pathways and centers. Hearing. Vocal organ. Phonation. Sound production. Echolocation; Eye and associated structures. Visual pathways and centers. Vision; Female; Fundamental and applied biological sciences. Psychology; hearing; Humans; Illusions - physiology; light; Male; Miscellaneous; Neurology; Photic Stimulation; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; sounds; Synaesthesia; Temporal binding; Vertebrates: nervous system and sense organs; vision; Visual Perception - physiology; Audio–visual; Double-flash illusion; Cross-modal integration; Temporal binding; Synaesthesia; Human; Hearing; Integration; Vision; Audio―visual; Illusion; Flash; Intermodal perception
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2012.07.011

Abstract It has been suggested that synaesthesia is the result of a hyper-sensitive multimodal binding-mechanism. To address the question whether multi-modal integration is altered in synaesthetes in general, grapheme-colour and auditory–visual synaesthetes were studied using the double-flash illusion. This illusion is induced by a single light flash presented together with multiple beep sounds, which is then perceived as multiple flashes. By varying the separation of auditory and visual stimuli, the hypothesis of a widened temporal window of audio–visual integration in synaesthetes was tested. As hypothesised, the results show differences between synaesthetes and controls concerning multisensory integration, but surprisingly other than expected synaesthetes perceive a reduced number of illusions and have a smaller time-window of audio–visual integration compared to controls. This indicates that they do not have a hyper-sensitive binding mechanism. On the contrary, synaesthetes seem to integrate even less than controls between vision and audition.