title: Taking aim at the Müller-Lyer goalkeeper illusion: an illusion bias in action that originates from the target not being optically specified.
abstract: Van der Kamp and Masters (2008) reported that goalkeeper postures that mimic the Müller-Lyer (1889) illusion affect the location of handball penalty throws. In four experiments, we aimed to verify that the effects on throwing are consistent with an illusory bias (Experiments 1 and 2), and to examine how these observations can be understood in the context of Milner and Goodale's (1995, 2008) two-visual systems model (Experiments 3 and 4). Experiments 1 and 2 confirmed that the goalkeeper Müller-Lyer posture may indeed induce an illusory bias in throwing, implying that allocentric information is used in far-aiming action tasks. Experiment 3 demonstrated that the bias was not related to a participant's throwing skill. Experiment 4 suggested that an absence of visual information to instantaneously specify target location may have induced use of context-dependent allocentric information, causing the throwing bias. The results are discussed in the context of recent debates about the roles of the two-visual systems in perception and action. It is suggested that the two systems are first and foremost perceptual systems that serve the pickup of different sources of information.
authors.affiliation: Department of Health, Human Performance & Recreation, Baylor University.
authors.forename: Jaeho
authors.initials: J
authors.lastname: Shim
authors.affiliation: Research Institute Move Amsterdam, Faculty of Human Movement Sciences, VU University Amsterdam.
authors.forename: John
authors.initials: J
authors.lastname: van der Kamp
authors.affiliation: Department of Health, Human Performance & Recreation, Baylor University.
authors.forename: Brandon R
authors.initials: BR
authors.lastname: Rigby
authors.affiliation: Department of Health, Human Performance & Recreation, Baylor University.
authors.forename: Rafer
authors.initials: R
authors.lastname: Lutz
authors.affiliation: Institute of Human Performance, University of Hong Kong.
authors.forename: Jamie M
authors.initials: JM
authors.lastname: Poolton
authors.affiliation: Institute of Human Performance, University of Hong Kong.
authors.forename: Richard S W
authors.initials: RS
authors.lastname: Masters
mesh_terms: D054874:Athletic Performance / Q000502:physiology; D001827:Body Height; D049628:Body Size; D004215:Distance Perception; D005260:Female; D006801:Humans; D008297:Male; D008960:Models, Psychological; D009039:Motion Perception / Q000502:physiology; D009903:Optical Illusions / Q000502:physiology; D009949:Orientation / Q000502:physiology; D010296:Parietal Lobe / Q000502:physiology; D010364:Pattern Recognition, Visual / Q000502:physiology; D011187:Posture; D012858:Size Perception; D013028:Space Perception / Q000502:physiology; D013702:Temporal Lobe / Q000502:physiology; D014793:Visual Cortex / Q000502:physiology; D014795:Visual Pathways / Q000502:physiology; D055815:Young Adult