People with Asperger syndrome, a mild form of autism, dramatically improve their social learning skills and spend more time gazing at pictures of faces after inhaling a whiff of the social-bonding hormone oxytocin, researchers have found.

The study, published Monday in the Proceedings of the National Academies of Science , is the first to show the effects of oxytocin, a hormone that promotes mother-infant bonding, socialization, trust and cooperation - in people diagnosed with Asperger's.

It led some experts to speculate that supplementing the normally low levels of oxytocin in people with autism spectrum disorders may help them to detect subtle social cues and engage in smoother social interactions.

In the report, 13 subjects with high-functioning Asperger syndrome and a control group matched for gender and age were asked questions about photographs of human faces - which would normally prompt Asperger subjects to avert their gaze and to avoid, especially, the person's eyes.

But for 90 minutes after inhaling oxytocin through the nose, eye-movement trackers showed that they were far more willing, though not quite as willing as controls, to explore faces, focusing longer on eyes.

In another test, subjects played a computerized ball-tossing game in which they were largely ignored by one fellow ball-tosser but became "favorites" of another. People with Asperger's would usually not pick up on their differential treatment. But those who had sniffed oxytocin were as accurate as controls in detecting which fellow player was "friendly" or not, and in responding in kind.

Co-author Angela Sirigu, director of research at of University of Lyons' Centre de Neuroscience Cognitive, said oxytocin's effect on interactive behavior was especially key as it prompted subjects to interact with others and "learn from others' feedback."

Clara Lajonchere, vice president for clinical programs for Autism Speaks, said that if proved safe and effective in a clinical setting, oxytocin would be the first medicine to target autism-spectrum disorder directly.

At least 800 of the 4.3 million babies born yearly in the U.S. are thought to suffer from the repetitive behaviors, social awkwardness and peculiar speech patterns that frequently characterize Asperger syndrome.