The hand knows something that the eye does not: Reaching movements resist the Müller–Lyer illusion whether or not the target is foveated

Previous reports suggest that saccades are affected by the Müller–Lyer (ML) pictorial illusion, whereas reaching movements are not. It is unclear if the resistance of reaching to illusions depends on the concurrent engagement of the oculomotor system. Here we show that the endpoints and kinematics of reaching movements were unaffected by a peripherally viewed ML stimulus regardless of whether or not a concurrent saccade was carried out. Primary saccade endpoints were affected by the ML stimulus but secondary saccades were not. Perceptual judgments of target location were influenced by the ML stimulus in the expected direction. The resistance of reaching movements to pictorial illusions does not appear to depend on the concurrent engagement of the oculomotor system. Implications for models of oculomotor and upper limb control are discussed.