A study by scientists at Indiana University tested 280 undergraduates of both genders on their ability to spot social signals.
They were shown photographs of women and asked to categorise them as friendly, sexually interested, sad or rejecting.
The male students were far less accurate than the females at interpreting the body language, and were particularly baffled by the difference between flirty and friendly gestures. When shown images of women making advances, men tended to misread the sexual cues as friendliness. At the same time they mistook photos of women merely being friendly for sexual interest.
The researchers also found that women overestimate men's ability to pick up on sexual signals.