title: The kinaesthetic mirror illusion: How much does the mirror matter?
abstract: The reflection of a moving hand in a mirror positioned in the sagittal plane can create an illusion of symmetrical, bimanual movement. This illusion is implicitly presumed to be of visual origin. However, muscle proprioceptive afferents of the arm reflected in the mirror might also affect the perceived position and movement of the other arm. We characterized the relative contributions of visual and proprioceptive cues by performing two experiments. In Experiment 1, we sought to establish whether kinaesthetic illusions induced using the mirror paradigm would survive marked visual impoverishment (obtained by covering between 0 and 100 % of the mirror in 16 % steps). We found that the mirror illusion was only significantly influenced when the visual degradation was 84 % or more. In Experiment 2, we masked the muscle proprioceptive afferents of the arm reflected in the mirror by co-vibrating antagonistic muscles. We found that masking the proprioceptive afferents reduced the velocity of the illusory displacement of the other arm. These results confirm that the mirror illusion is not a purely visual illusion but emerges from a combination of congruent signals from the two arms, i.e. visual afferents from the virtually moving arm and proprioceptive afferents from the contralateral, moving arm.
authors.affiliation: CNRS, LPNC UMR 5105, University Savoie Mont Blanc, 73000, Chambéry, France.|CNRS, NIA UMR 7260, 13331, Marseille, France.
authors.forename: Marie
authors.initials: M
authors.lastname: Chancel
authors.affiliation: CNRS, LPNC UMR 5105, University Savoie Mont Blanc, 73000, Chambéry, France.|Center for Interdisciplinary Research in Rehabilitation and Social Integration (CIRRIS), Laval University, Quebec, G1M 2S8, Canada.
authors.forename: Clémentine
authors.initials: C
authors.lastname: Brun
authors.affiliation: CNRS, NIA UMR 7260, 13331, Marseille, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Kavounoudias
authors.affiliation: CNRS, LPNC UMR 5105, University Savoie Mont Blanc, 73000, Chambéry, France. Michel.Guerraz@univ-smb.fr.
authors.forename: Michel
authors.initials: M
authors.lastname: Guerraz
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007088:Illusions / Q000502:physiology*; D007699:Kinesthesis / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D014732:Vibration; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
keywords: Kinaesthesia; Mirror illusion; Muscle proprioception; Visual impoverishment