The effect of lateralized pointing on processing tactile stimuli

Abstract

Prism adaptation is a well-known sensori-motor conflict/adaptation paradigm, which induces an adaptation to a visual shift and can improve spatial bias in neglect patients. However, recent research indicates that the prism induced visual shift during pointing movements is not necessary for spatial perception to be affected, lateralized sensori-motor experiences alone are sufficient to influence spatial processing. Different studies have shown that PA and LP induce quite similar results, both are capable to induce a spatial bias and all these results are in accordance with the idea that the working-mechanism of LP and PA are quite similar. The current study examines if LP could produce a supramodal effect and bias processing in the tactile modality, similar to PA. It was hypothesized that participants who stimulated one hemisphere by lateralized pointing to the contralateral half of space would process tactile stimuli to the contralateral hand faster compared to baseline. Participants performed a tactile temporal order judgements (TOJ) task both before and after LP. The results provide no evidence that lateralized pointing has an effect on tactile processing. A possible explanation for the incongruence between PA and LP could hence be that LP is capable to affect processes involved in space perception, but is not capable to sufficient affect high level multimodal representations the ensure a supramodal effect. The results of the current study could also indicate that LP has no effect on (several) lateralized functions, including tactile processing. However, current limitations could have affected the results. Further research redeemed from the current limitations would be helpful in order to draw a more definite conclusion.