Researchers have found that very young children and those with autism don’t contagiously yawn.
They tested 120 typically developing 1 – 6 year olds and 30 6 – 15 year-olds with autism spectrum disorders (ASD) to see if they would yawn in response to seeing other people yawn. (Child Development Vol 81 No 5).
About 50% of adults yawn contagiously but in this study only typically developing children aged 4 and older reliably yawned when they watched others yawn. And across all ages the children with autism were less likely to yawn compared to their same-age peers.
The researchers believe that contagious yawning might reflect empathetic feelings and that very young children and children with ASD experience these feelings less than older or typically developing children.