When 2-year-olds with autism look at someone’s face, they may crave synchronized detection rather than social connection. Toddlers with this developmental condition track sounds and sights that occur together, such as a mother’s lips moving in time with sounds coming out of her mouth, rather than social cues, such as the gleam in that same mother’s eyes, a new study suggests.
Locked in a world of co-occurring sound and motion, youngsters with autism neglect social signals that critically contribute to mental and brain development, propose psychologist Ami Klin of Yale University’s Child Study Center and his colleagues.
“Our findings lead us to the rather sad hypothesis that a toddler with autism might watch a face but not necessarily experience a person, since so much of that experience involves mutual eye gaze,” Klin says.
The new study, published online March 29 in Nature, indicates that by age 2, kids with autism don’t notice the array of cues indicating that a body is moving. Non-autistic children do so within days of birth. Young animals in many species, from humans to birds, monitor signs of movement by others as cues to initiate social contact.
While earlier studies have suggested that children with autism often don’t look at other people’s eyes, it’s been unclear why this behavior occurs. Few studies have included toddlers or infants with autism, who are difficult to diagnose.
“For the first time, this study has pinpointed what grabs the attention of toddlers with autism spectrum disorders,” remarks psychiatrist Thomas Insel, director of the National Institute of Mental Health in Bethesda, Md.
Klin’s study employed point-light cartoons created with data from actors playing five children’s games. Each animation, consisting only of bright dots positioned at body joints, played normally on one side of a computer screen. On the other side, it played upside-down and in reverse. Children with no developmental problems have difficulty discerning movement by inverted figures.
A soundtrack of the actor’s voice and accompanying sound effects was played with each pair of cartoons.
Eye-tracking devices determined that 39 typically developing toddlers and 16 toddlers with non-autistic developmental delays preferred to look at upright animations, tracking biological motion. In contrast, 21 toddlers with autism generally tended to look back and forth at upright and reversed animated figures, suggesting that these children paid no attention to the moving bodies.
But toddlers with autism made an exception for a video with a cartoon that featured a game of patty-cake, where colliding dots that represented two hands repeatedly produced a clapping sound. This physical synchrony existed only for the upright figure because the inverted figure played in reverse so its motions didn’t match the soundtrack.
A closer analysis of other synchronized sounds and motions in the five cartoons indicated that sensory pairings almost always drew the attention of toddlers with autism.
It’s too early to say for sure whether autism really involves a focus on audio-visual synchronies, since a broader mental trait could explain Klin’s new findings, cautions psychologist and autism researcher Mark Strauss of the University of Pittsburgh. An intense focus on details may partly explain a tendency of kids with autism to ignore moving bodies while focusing on synchronized physical events (SN: 7/7/07, p. 4), Strauss suggests. Greater difficulty in detecting subtle eye movements versus larger mouth movements may also contribute to this pattern, he notes.
Questions remain about the extent to which kids with autism make eye contact. Klin’s team reported last year that 2-year-olds with autism mainly look at people’s mouths. But in an upcoming study, Strauss’ group finds that 8- to 12-year-olds with autism look others in the eyes as much as their non-autistic peers.
Klin’s group now plans to see whether children with autism become more social after receiving training that directs attention away from synchronized sights and sounds and toward signs of biological motion.