Spatial reference frames used for tactile attention depend on developmental vision: Evidence from event-related potentials
Poster Presentation

Brigitte Roeder
Biological Psychology and Neuropsychology, University of Hamburg (Germany)

Julia Foecker
Biological Psychology and Neuropsychology, University of Hamburg (Germany)

Kirsten Hoetting
Biological Psychology and Neuropsychology, University of Hamburg (Germany)

Charles Spence
Experimental Psychology, University of Oxford (UK)

     Abstract ID Number: 120
     Full text: Not available
     Last modified: March 17, 2006
     Presentation date: 06/19/2006 4:00 PM in Hamilton Building, Foyer
     (View Schedule)

Abstract
Studies manipulating the direction of eye gaze or limb posture suggest that an eye-centred or external spatial reference frame is used to bind stimuli crossmodally. In contrast to sighted individuals, the congenitally blind do not seem to be detrimentally affected by changes in limb posture (such as crossing the hands) in tasks such as tactile temporal order judgments. This suggests that they use an anatomically- rather than an externally-anchored reference system as the default for tactile localization. Twelve congenitally blind and twelve matched sighted adults were instructed to detect tactile deviant stimuli on the hand indicated by a preceding tone while ignoring stimuli presented to the other hand and all frequent stimuli at both hands. The task was performed with the hands placed in either an uncrossed or crossed posture. While sighted participants performed much less accurately when they crossed their hands, the congenitally blind participants did not show any such crossed hands deficit. For the sighted participants, a frontal negativity was observed between S1 (the tone) and S2 (the tactile stimulus) contralateral to the position of the hand in space. By contrast, the congenitally blind participants hardly showed any signs of such an attention-directing negativity. Attention effects on somatosensory ERPs (to S2) were delayed and markedly attenuated in the sighted when their hands were crossed as compared to when they were uncrossed. By contrast, ERPs to S2 were indistinguishable for both posture conditions in the blind. The results from the sighted participants suggest that both attention control mechanisms and spatial attention mechanisms enhancing the processing of stimuli presented at a task-relevant location remap tactile events into an external reference frame. The set-up of the former and the default activation of the latter attention mechanism would appear to depend on developmental vision.