The antipointing task: vector inversion is supported by a perceptual estimate of visual space

The authors examined whether the visual field-specific endpoint bias of mirror-symmetrical reaching movements (i.e., antipointing) is related to top-down decoupling of the normal spatial relations between target and response (i.e., visuomotor inhibition) or the inversion of target coordinates to a mirror-symmetrical location (i.e., vector inversion). Participants completed pro- and antipointing movements in left and right visual space under conditions in which movement type was performed in separate blocks (i.e., blocked condition) and when randomly interleaved on a trial-by-trial basis (i.e., random condition). Most important, the random condition entailed equivalent premovement inhibition across pro- and antipointing. Propointing produced comparable endpoint accuracy in left and right visual space whereas antipointing under- and overshot target position: a finding characterizing blocked and random conditions. The authors attribute the visual field-specific bias of antipointing to the obligatory nature of the task and the integration of visuoperceptual networks to support vector inversion.