Attentional processes following prism adaptation; Saccadic eye movements as an indicator of bottom-up and top-down processing.

Abstract

Prism adaptation is a treatment method that is known to ameliorate neglect symptoms. However, the underlying mechanisms of this method are poorly understood. The objective of the present research was to increase the understanding of deviating attentional processes evoked by prism adaptation. It is known that healthy subjects show a rightward deviation following a treatment with leftward displacing prism goggles, resembling neglect symptoms. In this study, we examined these effects of prism adaptation on oculomotor selection. The performance of healthy subjects on a saccadic paradigm was examined both before and after prism adaptation took place. In the experiment, a single stimulus appeared on half of the trials, whereas on the other half of the trials a distractor stimulus appeared simultaneously on the opposite site. The saccadic items that involve single stimulus presentation entail bottom-up processing, while simultaneous bilateral target presentation involves top-down processing. Results indicate that neither top-down nor bottom-up processing seems to be influenced by prism adaptation in healthy subjects. Before and after prism adaptation, location of stimulus presentation (left versus right) did not influence saccade latency. In agreement with previous findings in neglect patients, bottom-up processing is unaltered by prism adaptation, indicating that prism adaptation does not influence automatic attraction of attention, which is driven by properties inherent in stimuli in both healthy subjects and neglect patients. However, previous findings in neglect patients did show amelioration of deviations in top-down processing. The current research demonstrated unaltered top-down processing in healthy subjects after prism adaptation. These deviating outcomes regarding the effect of prism adaptation on top-down processing could be due to differences between the top-down involvement in the tasks employed by these studies.