@article {Schubert056515, author = {Jonathan T. W. Schubert and Stephanie Badde and Brigitte R{\"o}eder and Tobias Heed}, title = {Task demands affect spatial reference frame weighting during tactile localization in sighted and congenitally blind adults}, elocation-id = {056515}, year = {2016}, doi = {10.1101/056515}, publisher = {Cold Spring Harbor Laboratory}, abstract = {Task demands modulate tactile localization in sighted humans, presumably through weight adjustments in the spatial integration of anatomical, skin-based, and external, posture-based information. In contrast, previous studies suggested that congenitally blind humans, by default, localize touch based on skin-based information and refrain from automatic spatial integration. Accordingly, task context should not affect blind participants{\textquoteright} tactile localization performance in tasks that do not require external coding. Here, sighted and congenitally blind participants localized tactile targets on the palm or back of one hand, while ignoring simultaneous tactile distractors at congruent or incongruent locations on the other hand. Hand posture was varied either blockwise or trial-by-trial, to probe the interplay of anatomical and external location codes for spatial congruency effects: either both palms faced down, or one faced down and one up. In the latter posture, externally congruent target and distractor locations were anatomically incongruent. Target locations had to be reported either anatomically ({\textquotedblleft}palm{\textquotedblright} or {\textquotedblleft}back{\textquotedblright} of the hand), or externally ({\textquotedblleft}up{\textquotedblright} or {\textquotedblleft}down{\textquotedblright} in space). Under anatomical instructions, performance was better for anatomically congruent than incongruent target-distractor pairs. In contrast, under external instructions, performance was best when target-distractor pairs were externally congruent. These modulations were comparable in sighted and blind individuals, even if effects were smaller in the latter. Whether posture was changed blockwise or trial-by-trial did not significantly modulate congruency effects. These results suggest that blind individuals, like the sighted, automatically integrate anatomical and external information during tactile localization, and that integration is modulated by top-down information - here, task instruction. Thus, the integration of anatomical and external spatial information in tactile processing is flexibly adapted to current task demands even in the absence of developmental vision.}, URL = {https://www.biorxiv.org/content/early/2016/06/12/056515}, eprint = {https://www.biorxiv.org/content/early/2016/06/12/056515.full.pdf}, journal = {bioRxiv} }