Everything is Illuminated: Prismatic Adaptation Lowers Visual Detection Threshold in Normal Subjects

Prismatic adaptation (PA) results from repeated ballistic movements of the dominant arm toward visual targets while wearing prisms shifting the visual field laterally (visuomotor prismatic training [VPT]). Following PA, subjects' pointing movements are deviated contralaterally to prismatic shift (aftereffect). The question of whether spatial attention is also biased in the same direction remains controversial in the scientific literature. To investigate the effect of PA on spatial attention, we asked healthy participants to perform a visual detection threshold task before and after VPT with left- and right-deviating prisms and visuomotor training without prisms. Our results demonstrate that both left and right VPTs modulate visual detection threshold, significantly ameliorating detection accuracy and response times bilaterally. These data indicate that PA modulates visual attention bilaterally and that detection threshold paradigms are sensitive to its effects in the visual domain. We suggest that the described PA effects are mediated by the joint action of attentional and alerting mechanisms