London ? It wasn’t until Jude met Jenny that the 3-year-old autistic boy understood what happy people look like.

Jenny, a green trolley car with a human face, had a furrowed brow when her wheel buckled and she got stuck on a track. But after being rescued by friends, she smiled broadly — and that’s when something clicked for little Jude Baines.

“It was revelatory,” his mother, Caron Freeborn told AP Television News in Cambridge, England. Before watching the video, Jude didn’t understand what emotions were and never noticed the expressions on people’s faces, even those of his parents or younger brother.

Jenny’s adventures are part of a DVD for autistic children released this week in the United States called The Transporters.

The DVD teaches autistic children how to recognize emotions like happiness, anger and sadness through the exploits of vehicles including a train, a ferry, and a cable car.

It is the brainchild of Simon Baron-Cohen, director of the Autism Research Centre at Cambridge University. He also happens to be a cousin of Sacha Baron-Cohen, the comedian behind the character Borat, the crass Kazakh reporter.

Baron-Cohen first became interested in autism in the 1980s while teaching autistic children. “Why should social interaction be so difficult for a child who has very good skills in other areas like memory or an attention to detail?” he wondered.

About a decade ago, Baron-Cohen suggested that autism — which is much less likely to afflict girls — might be an extreme version of the typical male brain. Men tend to understand the world via patterns and structure, whereas women are more inclined to understand emotions and sympathize with others.

Autism, Baron-Cohen believes, is a condition where people perceive systems and patterns while remaining almost oblivious to other people and their feelings.

To help autistic children understand emotions, Baron-Cohen and his team use eight track-based vehicles in their DVD. The vehicles have human faces grafted onto them, making focusing on human features unavoidable. The video was financed by the British government.

“To teach autistic children something they find difficult, we needed an autism-friendly format,” Baron-Cohen said. Autistic children are particularly drawn to predictable vehicles that move on tracks like trains and trams. For years, parents of autistic children have noted their children’s attachment to Thomas the Tank Engine.

“Autistic children are often puzzled by faces, so this video helps focus on them in a way that makes it very appealing and soothing,” said Uta Frith, an emeritus professor of cognitive development at University College London, who was not involved in developing the video.

Frith said the DVD was a way for autistic children to learn social skills the way other children might learn math or a foreign language.

In a small study of 20 autistic children between ages 4 and 7, Baron-Cohen and colleagues found that autistic children who watched the video for at least 15 minutes a day for one month had caught up with normal children in their ability to identify emotions.

But Baron-Cohen cautioned that while autistic children might be able to recognize emotions better after watching the DVD, that would not necessarily change their behavior at home or on the playground.