Independent effects of eye gaze and spatial attention on the processing of tactile events: Evidence from event-related potentials

• Is the effect of gaze on touch mediated by attentional mechanisms?
• Previous studies manipulated gaze direction but not spatial attention.
• Here, both gaze and spatial attention are simultaneously manipulated.
• SEPs modulations by gaze and attention have different patterns and time courses.
• The effects of gaze and attention on touch are independent.

Directing one’s gaze at a body part reduces detection speed and enhances the processing of tactile stimuli presented at the gazed location. Given the close links between spatial attention and the oculomotor system it is possible that these gaze- dependent modulations of touch are mediated by attentional mechanisms. To investigate this possibility, gaze direction and sustained tactile attention were orthogonally manipulated in the present study. Participants covertly attended to one hand to perform a tactile target-nontarget discrimination while they gazed at the same or opposite hand. Spatial attention resulted in enhancements of the somatosensory P100 and Nd components. In contrast, gaze resulted in modulations of the N140 component with more positive ERPs for gazed than non gazed stimuli. This dissociation in the pattern and timing of the effects of gaze and attention on somatosensory processing reveals that gaze and attention have independent effects on touch.