Image caption Subjects were put in a virtual child's body (mirror reflection shown here) or an adult body of the same size Image caption When in a child-sized body objects seemed larger than when in an adult body previous slide next slide

In a virtual world adults in a child-like body start to perceive the world more like a child, a study has shown.

Adults were either placed in a virtual four-year-old body or an adult body scaled down to the same size.

It was found that participants in the child's body overestimated the size of objects and identified better with child-like attributes.

Scientists say their work, published in PNAS, could help unlock hidden memories.

Wearing a head-mounted display and a motion capture suit that tracks body movements, adults were able to move in a virtual world just as they would in the real world.

Previous research has already shown that the brain is amenable to accepting such illusory changes. So if a person moves at the same time their virtual body does, they feel as if they are really moving.

Body illusion

A team led by Mel Slater from the University of Barcelona found three situations in which adult participants reacted differently depending on what virtual body they were in.

Embodiment illusions have already established that when placed in a small virtual body, surrounding objects seem larger. What was unexpected was that those in a child's body overestimated the sizes of objects to a greater extent.

Image caption Presented with two rooms, adults in a child-like body chose a child-like room

The participants were also asked to do an implicit association test, which requires participants to categorise themselves with child-like or adult-like attributes. Those in the child's body reacted faster to child-like attributes to those in the adult body.

A third scenario they were presented with was to pick a child or adult-like room. Those in a child's body preferred the child's room.

"This illusion of body ownership was responsible for these findings," Prof Slater told BBC News.

"Somehow the brain thinks 'this is my body' which makes the whole experience consistent. You see the world bigger, have more childlike attributes and prefer a child's environment rather than an adult one."

The researchers propose that their work has numerous applications, particularly for therapy or remembering childhood memories.

Image caption Participants' body movements were tracked using a motion capture suit

"You're putting yourself in the shoes of someone else, so you can get some aspect of how they feel to be in this position.

"To some extent you could revert people to a child-like experience, so they may be able to remember things from their childhood better or to empathise more with their own children."

Rehabilitate prisoners

He added that longer term studies were needed to discover if these changes still had an effect after the experiment.

Thomas Metzinger from the Johannes Gutenberg University, Germany, said the findings could have numerous applications.

"Virtual reality could help us take the perspective of victims, of young children and could help rehabilitate prisoners.

"It could help us understand how people really feel, maybe even in a crime scene to see what perspectives they had," Prof Metzinger told BBC News.

He added that it was not surprising that people easily identified with avatars as people increasingly live their day-to-day lives in a 'virtual world' of the internet, TV and computer games.

But like Prof Slater, he said it was unclear if a momentary insight into a virtual world could help facilitate empathy in the the long-term.