Motor contagion from gaze: the case of autism
1Centro di Scienza Cognitiva, Dipartimento di Psicologia, Università di Torino, 2Dipartimento di Psicologia Generale, Università di Padova, Italy, 3Department of Psychology, University of Melbourne, Australia and 4Department of Psychology, Royal Holloway-University of London, UK
Correspondence to: Umberto Castiello, Dipartimento di Psicologia Generale, Università di Padova, 35131, Padova, Italy E-mail: umberto.castiello{at}unipd.it
It has been proposed that motor contagion supplies the first step in mentalizing. Here, by using kinematic methods, we show that in contrast to normally developing children, children with autism seem to be immune to motor contagious processes. In the main experiment, involving twelve high-functioning autistic children (six males and six females, 10–13 years old, mean 11.1 years) and 12 normally developing controls (age and gender matched), two participants, a model and an observer, were seated facing each other at a table. The model was a normally developing child but the observer was either a normally developing or autistic child. The model was requested to grasp a stimulus or simply to gaze towards the target which could be presented alone or flanked by a distractor object. After watching the model, the observer was asked to grasp the object (always in the absence of the distractor). Despite the distractor being removed, the kinematics of normally developing children was affected by having observed an action performed in the presence of a distractor, thus revealing a transfer of interference from the model's action. Consistent with prior evidence, this transfer of interference effect was also present when the model simply looked at the target in the presence of the distractor object. In contrast, autistic children did not show any interference effect either from action or from gaze observation. A control experiment explored the importance of the information coming from the model's gaze pattern in eliciting the effects of motor contagion in normally developing children. In this case, the model was asked to fix their eyes on the target despite the presence of the distractor. Results highlight the importance of gaze direction in motor contagion, demonstrating that in normal children blocking the gaze prevented the transfer of interference. Altogether, these findings suggest that eye gaze plays a central role in eliciting motor contagion. We discuss these results in light of the deficit exhibited by children with autism in reading intentions from gaze.
Key Words: autism; eye gaze; motor contagion; motor interference; reach-to-grasp
Abbreviations: ADI-R, autism diagnostic interview-revised; CARS, childhood autism rating scale; DSM-IV, diagnostic and statistical manual of mental disorders-IV; FIR, finite impulse reponse; fMRI, functional magnetic resonance imaging; pSTS, posterior superior temporal sulcus; WISC-R, wechsler intelligence scale for children
Received April 4, 2007. Revised June 20, 2007. Accepted July 2, 2007.