Imitation in fragile X syndrome. Implications for autism.
In kids with fragile X, extra groping movements during imitation can flag co-occurring autism better than simple accuracy scores.
01Research in Context
What this study did
Macedoni-Luksic et al. (2009) watched kids with fragile X syndrome copy hand and finger movements. Some kids also had autism. The team scored how close each copy was to the model.
They looked at two groups: FXS only and FXS plus autism. Both groups tried the same imitation tasks in a quiet lab room.
What they found
Both groups got about the same number of moves right. Accuracy alone did not separate the kids.
The big clue was extra motion. Kids with FXS plus autism showed more groping and wandering hand paths. These extra moves were the red flag.
How this fits with other research
Du et al. (2024) saw lower imitation accuracy in autistic kids without FXS. Marta saw equal accuracy in FXS kids with autism. The difference is the group: Bang studied idiopathic autism; Marta studied autism tied to FXS. Same word "autism," different bodies.
Demily et al. (2018) also found good accuracy in intellectually able adults with ASD, but those adults still moved awkwardly when planning their own actions. Marta’s kids looked similar: right final form, messy path.
Thurman et al. (2015) later mapped how autism traits grow differently in FXS across time. Marta’s 2009 focus on groping fits that slower, bumpier developmental track.
Why it matters
When you test imitation in kids with FXS, ignore the old rule of counting only right or wrong. Watch for extra wiggles, finger taps, or hand loops. Those movement errors can signal autism layered on FXS and guide you to add motor planning support, not just more imitation drills.
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02At a glance
03Original abstract
To address the specific impairment of imitation in autism, the imitation abilities of 22 children with fragile X syndrome (FXS) with and without autism were compared. Based on previous research, we predicted that children with FXS and autism would have significantly more difficulty with non-meaningful imitation tasks. After controlling for full-scale IQ and age, the groups did not differ in their overall imitation accuracy scores, but analysis of error patterns revealed that children with FXS and autism made more groping errors and additional movements than the comparison group. These error patterns are consistent with the hypothesis that an action production system deficit plays an important role in the overall imitation deficit in autism, at least in children with FXS.
Autism : the international journal of research and practice, 2009 · doi:10.1177/1362361309337850