Children typically copy adult behavior as a social phenomenon. They don't do this to learn new skills and this differs among those with autism.
In their study, psychologists at The University of Nottingham found that autistic children, who have profound difficulty in engaging in social situations, were less likely to copy unnecessary behaviour when learning a new task.
The research could offer a new approach to examining social development in children and adults with disorders on the autistic spectrum.
"Our study showed that typically developing children copy everything an adult does, even when they know that some of the actions are 'silly," Dr Antonia Hamilton, who led the research in the University's School of Psychology, said.
"In contrast, the children with autism only copied the useful actions - in a way, they are getting the job done more efficiently than the typical children."
"These results show us that copying unnecessary actions is a social phenomenon, it is not just about learning how to use objects," she said.
The scientists tested 31 children on the autistic spectrum and 30 typically developing children with the same level of language skills and a further 30 typically developing children who were matched by age.
In the study, children were asked to watch carefully as an adult showed them how to retrieve a toy from a box or to build a simple object.
Critically, the demonstration included two vital actions such as unclipping and removing the lid and one superfluous action such as tapping the top of the box twice.
The child was then asked to get or make the toy as fast as they could - without mentioning the need to copy all of the actions of the adult exactly as they had seen them.
Over 97 percent of the children were able to complete the tasks of fetching or making the toy.
Typical children also copied 43-57 percent of the unnecessary actions, while the autistic children copied only 22 percent.
After doing the actions, the children were asked to watch the demonstration again, and judge if each action was "sensible" or "silly".
All children could do this task, but typical children found it easier. This means that typical children copied the unnecessary actions even though they know the actions are silly.
These results found a striking difference between autistic and typical children in both whether they copied the unnecessary actions and how they discriminated between the rationality of each action.
The scientists argue that typical children copy everything an adult does because they are more eager to please and to "fit in".
The study is published in the journal Current Biology.