Younger children who use gestures perform better in a problem-solving task than their peers, a new study has found.

Scientists from San Francisco State University, asked kids to complete a relatively simple task - sorting cards printed with coloured shapes first by colour, and then by shape.

But the switch from colour to shape can be tricky for children younger than 5, said Professor of Psychology Patricia Miller.

Miller and SF State graduate student Gina O'Neill found that young children who gesture are more likely to make the mental switch and group the shapes accurately.

In fact, gesturing seemed to trump age when it came to the sorting performance of the children, who ranged from 2 and a half years old to 5 years old.

In the colour versus shape task, as well as one that asked children to sort pictures based on size and spatial orientation, younger children who gestured often were more accurate in their choices than older children who gestured less.

The children's gestures included rotating their hands to show the orientation of a card or using their hands to illustrate the image on the card, for example gesturing the shape of rabbits' ears for a card depicting a rabbit.

"Gina and I were surprised by the strength of the effect. Still, the findings are consistent with a growing body of research showing that mind and body work closely together in early cognitive development," Miller said.

O'Neill and Miller observed the children's spontaneous gestures as they performed the tasks, as well as gestures they were encouraged to make to explain their sorting choices. Both kinds of gestures were counted in comparing high and low gesturing children.

Children who did a lot of gesturing did better at the sorting task than those who didn't gesture as much - even when they did not use gesturing during the task itself, the researchers found.

This makes it difficult to determine whether it's the gesturing itself that helps the children perform the task, or whether children who use a lot of gestures are simply at a more advanced cognitive level than their peers, researchers said.

Miller said there is "quite a bit of evidence now that gestures can help children think," perhaps by helping the brain keep track of relevant information or by helping the brain reflect on the possibilities contained within a task.

The study will be published in the journal Developmental Psychology.