Young children with autism appear to be delayed in their ability to categorize objects and, in particular, to distinguish between living and nonliving things, according to a breakthrough study by researchers at Children's Hospital of Pittsburgh and Carnegie Mellon University. The paper has been published in the Journal of Developmental and Physical Disabilities and the results could provide a cognitive explanation for one of the characteristics of autism: the inability to recognize the goals and motivations of others.

Previous research has shown that young children with autism have the same abilities as normally developing children to categorize objects based on so-called surface characteristics, such as size and shape. They have a diminished ability, however, to group objects into more abstract categories (e.g., birds, trees, cars and furniture). A key characteristic that differentiates living and nonliving things is the ability of the former to move on their own, and as humans, we rely on the motions of others -- a hand reaching out to shake ours, a person running toward us -- to help us interpret their actions and intentions.

"People have not really studied these conceptual deficits in very young children as the possible basis for the social and cognitive deficits in older children and adults with autism," said Carnegie Mellon psychologist David Rakison, who co-authored the paper with Cynthia Johnson, director of the Autism Center at Children's Hospital of Pittsburgh and assistant professor of pediatrics and psychiatry at the University of Pittsburgh Medical Center.

"This study opens the door for further research of preschool-age children, which could aid us in the development of possible diagnostic tools and therapies," Johnson said. "Children with autism have the best outcomes when they are diagnosed and begin treatment at an early age."

In this study, 11 children with autism, ranging in age from 34 to 46 months, performed a series of tasks -- some involving toy figures and others in which children followed objects moving on a computer monitor. In one experiment, children were asked to imitate the actions of a researcher who moved an object, such as a toy cat. Children were able to choose from other objects with varying degrees of similarities to the original toy. In the case of the toy cat, they could choose from a toy dog (the same category and the same parts); a toy dolphin (same category but different parts); a table (the same parts -- legs -- but in a different category); and a car (different parts and in a different category.) Researchers studied the children's play to see whether they chose a toy in the same category and with the same parts as the object chosen by the researcher, and whether they demonstrated the appropriate type of motion.

The authors found that the children with autism performed at the same level as children half their age (18 to 22 months). Children with autism could understand the relationship between certain parts and motion, like legs and walking, but ignored other important characteristics, such as the fact that some things with legs are alive and move deliberately toward other objects.

"I've never seen a single paper in which researchers studied these processes in children this young," Rakison said.

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Contact: Jonathan Potts
Carnegie Mellon University