Motor Resonance in Adolescents and Adults with Autism Spectrum Disorder

Background: Motor resonance is motor activation that occurs in the body when one observes or thinks about movement.  Motor resonance is thought to assist in automatic imitation, the development of language (e.g., watching others speak helps a person learn to move their mouth to form the words), the development of empathy (e.g., watching others get hurt makes a person automatically flinch), and the development of motor ability (e.g., watching someone ride a bike should help a person ride it later), all of which are impaired in persons with Autism Spectrum Disorder (ASD). The expression of motor resonance is thought to be supported by the Mirror Neuron System. Thus, motor resonance may relate in important ways to the social, language, affective, and motor atypicalities commonly observed in persons with ASD.

Objectives: The present study used social stimuli (e.g., videos of hand movements), nonsocial stimuli (e.g., videos of objects spinning), and language stimuli (e.g., sentences about movement) to examine the presence of motor resonance in individuals with ASD. All of these videos were non-emotional by nature in order to examine possible group differences in motor resonance that was not driven by attention to affective information.

Methods: Twenty-six individuals with ASD and 26 age-and-IQ-matched individuals with typical development (between the ages of 16 and 30) completed a motor resonance computer game in which each video or sentence portrayed a clockwise or counter-clockwise movement. Participants were instructed to respond to the stimuli by rotating a joystick either clockwise or counter-clockwise in response to a colored square presented on the screen during each video or sentence.  Because motor resonance facilitates responses in the same direction as the observed movement (congruent condition) and inhibits responses in the opposite direction of the observed movement (incongruent condition), quicker congruent responses compared to incongruent responses indicate the presence of motor resonance. Current ASD symptoms were assessed using the Social Responsiveness Scale (SRS).

Results: The results indicated that individuals with ASD demonstrated a similar pattern of motor resonance compared to individuals with typical development across the different types of stimuli (social, non-social, and sentences), F(1,50)=1.24, p =.27.  However, within the ASD group, the degree of motor resonance was significantly correlated with current symptom severity (SRS), r = -.45, p=.02, suggesting that those with more severe ASD symptoms demonstrated less motor resonance.

Conclusions: The present results suggest overall intact motor resonance in adolescents and adults with ASD. The specific methods of this task (lack of emotionally valenced stimuli and use of a motor response to each stimulus) were designed to decrease attention and social demands, which may explain the lack of overall group differences. Intact motor resonance in this population may be behaviorally indicative of intact mirror neuron functioning. Nevertheless, those with more severe ASD symptoms were less likely to demonstrate motor resonance, suggesting that motor resonance may be intimately intertwined with ASD symptom expression. Thus, motor resonance impairments may be evident in a group with more severe symptomatology. Future research and clinical implications are discussed.