Any interaction with a member of the opposite sex can bring a glow to a woman''s face, according to a new study.

Researchers at the University of St Andrews found contact with men - even non-sexual contact - caused a noticeable rise in the temperature of a woman''s face.

The team used thermal imaging to detect temperature changes when heterosexual women met other people.

They found that even without noticing, a woman''s face would get slightly hotter (about 1 degree) in the company of the opposite sex.

Lead author of the study, Amanda Hahn, said "This thermal change was in response to simple social interaction, without any experimental change to emotion or arousal. Indeed our participants did not report feeling embarrassment or discomfort during the interaction."

The study team claimed that thermal imaging could be developed to monitor level of stress and emotion in future, for example in lie detection tests.

The researchers took skin temperature readings on a woman''s hand, arm, chest and face when they chatted with men and found the most dramatic increase occurred in a woman''s face,

The study - to be published in Biology Letters - shows that gender alone was the key - as women showed very little thermal response to interaction with other women.

Research team member Prof David Perrett added, "We are only just beginning to understand the potential uses of thermal imaging in medicine and it can be very useful in areas of national security, where changes in skin temperature can be gauged as part of lie detection tests."