Virtual reality is allowing scientists to ask difficult questions about human behaviour that were previously not possible or were thought too unethical.

A Spanish team has designed a trial that allows men to step inside the body of a woman subjected to violence.

Meanwhile scientists in London are simulating a controversial experiment from the 1960s in which people were persuaded to inflict pain on others.

The original experiments were condemned as immoral and too traumatic.

At Barcelona University, male volunteers have experienced life as a virtual young girl and then separately, witnessed violence towards her.

On returning to live the girl's virtual life, the men empathized with her more than usual, feeling scared and insecure themselves.

"I want to know whether you can use virtual reality, not just to transform the place you are in, but also to transform your very self," said Mel Slater, lead researcher at the Catalan Institute of Research and Advanced Studies.

"If you see yourself in a virtual body, which moves as you do, how will this affect your behaviour?"

Virtual cruelty

Male volunteers in the Spanish experiment see a virtual room with a woman in front of them caressing their arm. Meanwhile, the illusion is reinforced by someone actually running their fingers down their arm in real life.

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