title: Touch Accelerates Visual Awareness.
abstract: To efficiently interact with the external environment, our nervous system combines information arising from different sensory modalities. Recent evidence suggests that cross-modal interactions can be automatic and even unconscious, reflecting the ecological relevance of cross-modal processing. Here, we use continuous flash suppression (CFS) to directly investigate whether haptic signals can interact with visual signals outside of visual awareness. We measured suppression durations of visual gratings rendered invisible by CFS either during visual stimulation alone or during visuo-haptic stimulation. We found that active exploration of a haptic grating congruent in orientation with the suppressed visual grating reduced suppression durations both compared with visual-only stimulation and to incongruent visuo-haptic stimulation. We also found that the facilitatory effect of touch on visual suppression disappeared when the visual and haptic gratings were mismatched in either spatial frequency or orientation. Together, these results demonstrate that congruent touch can accelerate the rise to consciousness of a suppressed visual stimulus and that this unconscious cross-modal interaction depends on visuo-haptic congruency. Furthermore, since CFS suppression is thought to occur early in visual cortical processing, our data reinforce the evidence suggesting that visuo-haptic interactions can occur at the earliest stages of cortical processing.
authors.affiliation: Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy; Institute of Neuroscience, CNR, Pisa, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Lunghi
authors.affiliation: Institute of Neuroscience, CNR, Pisa, Italy; Department NEUROFARBA, University of Florence, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Lo Verde
authors.affiliation: School of Psychology, University of Sydney, NSW, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Alais
keywords: multisensory/cross-modal processing; psychophysics; rivalry/bistability; visuo-haptic interactions