Abstract
Cross-talk between visual and tactile modalities influences on very different levels from neural activities, perception to higher cognition and behaviour. Many researches showed that one modality alters the other modality perception. There are some plausible explanations for those perceptual changes by multisensory inputs. The viewpoint of “Pre-attention effect” which is attention drawn by another modality(vision) facilitates the tactile encoding is more advocated by many researches. However, the timing issue between two modalities is critical in order to insist that attention across modality enhances perceptual sensitivity(detection threshold). So, the aim of this study is how vision influences on tactile sensitivity according to temporal synchrony. Total 15 subjects were given to perform the 2FAC task whether tactile pulse is felt. Even 6 points of tactile sub-threshold including none condition are randomly set to observe psychophysical detection performance. Visual stimuli are simultaneously provided with SOAs (0,±50,±100,±300) and no visual stimulus was given to Tactile Only condition. Discriminability between visual and tactile stimulus shows better when two stimuli are apart so does not interrupt each other(SOA±300 or Tactile Only). However, the tactile threshold is more sensitive when providing with visual stimulus, especially when visual stimulus precedes 50ms than tactile one. The change of detection sensitivity at a certain time period(vision is presented forward 50ms) implies that attention is drawn across sensory modality and it facilitates perceptual sensitivity. Therefore, it is hard to say that multisensory input leads perception of other sensory modality and would rather say attention across modality enhances perceptual sensitivity.