title: Anti-pointing is mediated by a perceptual bias of target location in left and right visual space.
abstract: We sought to determine whether mirror-symmetrical limb movements (so-called anti-pointing) elicit a pattern of endpoint bias commensurate with perceptual judgments. In particular, we examined whether asymmetries related to the perceptual over- and under-estimation of target extent in respective left and right visual space impacts the trajectories of anti-pointing. In Experiment 1, participants completed direct (i.e. pro-pointing) and mirror-symmetrical (i.e. anti-pointing) responses to targets in left and right visual space with their right hand. In line with the anti-saccade literature, anti-pointing yielded longer reaction times than pro-pointing: a result suggesting increased top-down processing for the sensorimotor transformations underlying a mirror-symmetrical response. Most interestingly, pro-pointing yielded comparable endpoint accuracy in left and right visual space; however, anti-pointing produced an under- and overshooting bias in respective left and right visual space. In Experiment 2, we replicated the findings from Experiment 1 and further demonstrate that the endpoint bias of anti-pointing is independent of the reaching limb (i.e. left vs. right hand) and between-task differences in saccadic drive. We thus propose that the visual field-specific endpoint bias observed here is related to the cognitive (i.e. top-down) nature of anti-pointing and the corollary use of visuo-perceptual networks to support the sensorimotor transformations underlying such actions.
authors.affiliation: School of Kinesiology, The University of Western Ontario, London, ON, N6A 3K7, Canada. mheath2@uwo.ca
authors.forename: Matthew
authors.initials: M
authors.lastname: Heath
authors.forename: Anika
authors.initials: A
authors.lastname: Maraj
authors.forename: Ashlee
authors.initials: A
authors.lastname: Gradkowski
authors.forename: Gordon
authors.initials: G
authors.lastname: Binsted
mesh_terms: D001921:Brain / Q000502:physiology; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology; D007839:Functional Laterality / Q000502:physiology*; D006225:Hand / Q000294:innervation / Q000502:physiology; D006801:Humans; D007858:Learning / Q000502:physiology; D008297:Male; D008568:Memory / Q000502:physiology; D009068:Movement / Q000502:physiology*; D009415:Nerve Net / Q000502:physiology; D009483:Neuropsychological Tests; D015588:Observer Variation; D009949:Orientation / Q000502:physiology*; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000502:physiology*; D012438:Saccades / Q000502:physiology; D013028:Space Perception / Q000502:physiology*; D014794:Visual Fields / Q000502:physiology*; D055815:Young Adult