Egocentric and allocentric visual cues influence the specification of movement distance and direction

The authors investigated whether visuomotor transformations that support the computation of movement distance (i.e., extent) and movement direction rely differentially on integration of egocentric and allocentric visual information. To accomplish that objective, the authors factorially arranged 17 participants' open-loop reaching movements from 2 movement-start locations with mediolateral (ML) and anteroposterior (AP) variants of the induced Roelofs effect (IRE). The 2 movement-start locations in combination with the 2 IRE configurations enabled the authors to examine the impact of illusory movement pertaining to distance (i.e., AP-IRE) and direction (i.e., ML-IRE) information. AP-IRE and ML-IRE configurations across the 2 movement-start locations reliably influenced reaching endpoints in a direction consistent with the perceptual effects of the illusion. These findings suggest that unitary visual information involving interactive egocentric and allocentric visual cues supports the specification of both movement distance and movement direction.