Interpersonal Sensory-Motor Synchronization in Adults with and without ASD during a Joint Improvisational Mirror Game
Recent research on Autism Spectrum Disorders (ASD) suggests that individuals with autism may have a basic deficit in synchronizing with others, and that this difficulty may lead to more complex social and communicative deficits. The current project aims to conduct an in-depth investigation of interpersonal sensory-motor synchrony in ASD, using an innovative experimental paradigm - the Mirror Game (MG, Fig 1) – that allows high-resolution temporal and spatial motion tracking in an open-ended joint improvisation game (Noy et al., 2011). Using the MG, it has been shown that players can attain moments of highly synchronized co-confident (CC) motion, in which the players act as a coupled unit.
To investigate the ability of adults with ASD, as compared with typically developing (TD) adults, to synchronize their movements with another person.
Participants: data from 27 participants with high-functioning ASD was compared with that of 39 TD adults.
MG procedure: two players face each other holding handles which can move along parallel tracks, and are told to “imitate each other, create synchronized and interesting motions, and enjoy playing together” (Fig 1a,b). All participants played against the same expert improviser. Participants were instructed to first lead the motion (Leader), then follow the experimenter’s motions (Follower), and then engage in Joint Improvisation (JI), with no designated leader; in 3-minute trials. The motion of the two handles is sampled at 50 HZ (Fig 1c,d).
Data analysis: Players’ synchronization was measured using the mean relative difference in velocity (dV) and the timing differences between zero-velocity events (dT). Segments of CC motion (Fig 1d) met the following criteria: dv<0.95, dT<0.15, and no more than one crossing of the acceleration=0 point (i.e., smooth movement, with no corrective jitter).
We found that individuals with autism can attain co-confident (CC) motion when playing the MG with an expert improviser. ASD participants engaged in overall less CC than TD participants (main effect of Group, F(1,64)=10.6, p<.001), and this was particularly pronounced when following an expert improviser (main effect of Role, F(2,128)=7.11, p<.001; and interaction effect of Role by Group, F(2,128)=9.2, p<.001; post-hoc between-group analyses in the Following round, t(64)=6.78, p<.001). Furthermore, ASD participants stayed in CC periods for a shorter duration of time than TD participants (F(1,61)=8.82, p=0.04).
These data provide the first evidence, to our knowledge, that individuals with autism can attain highly synchronized, co-confident motion, when playing with another player in an open-ended joint improvisation game. At the same time, they suggest that individuals with ASD have an attenuated ability to engage and stay in highly synchronized motion over time. It is possible that individuals with ASD do not detect these periods of CC motions, or do not find them rewarding, hence leading them to disengage earlier from the synchronized motion. Future research should focus on determining the reasons for this attenuated synchronization on both motor and psychological levels.
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