When they were physically touched by a male researcher, women really are "heated" - the skin temperature increased, particularly in the face and chest.

"The women showed an increase in temperature when were involved in social contact with a male investigator," said lead study researcher Amanda Hahn of the University of St. Andrews, United Kingdom. "For some women the temperature increased by almost one degree."

These changes occur unconsciously. Discover how temperature changes of the skin in response to stress and other emotional factors may help researchers develop a lie detector sensor without any contact.

The face is hot when we are under stress or when we get angry or scared. The researchers wanted to know how other emotions influence the temperature of the face, so they took pictures of the heat emitted two groups of young women during heterosexual interaction in series with a researcher, who touched his arm, palm, face and chest.

When a researcher (any kind) touching one of the participants, the skin temperature was increased on average about 0.1 ° C. The effect was not significant when played on the arm or the palm of your hand, but if there was much variation when they played in the face and chest.

The change was three times higher when the researcher was a man. The skin temperature reached 0.3 ° C increase to half when a male investigator touched the face or chest.

The researchers say this increase is considerably large for a change in facial temperature. "This magnitude of change would be the logic for any explicit emotional stressor" such as fear or stress, said Hahn. "In the study we manipulated the emotional or affective state of individuals, it was a subtle social interaction with the researcher ... but the reactions were very significant."

Many participants were aware of the change in temperature of your skin, but, "Only a quarter of them reported feeling an emotional change. The rest did not notice anything consciously," said Hahn.

Researchers can not confirm whether these changes are visible to the eye, or can be detected by touch. If there are people that can detect these changes, they could use that information as signals of nonverbal communication.