Eye dilation sex specific but not sexually explicit, study finds

Researchers from the University's School of Psychology studied whether a stronger dilation for the preferred sex is produced when participants viewed images depicting higher levels of sexual explicitness compared to images low on sexual explicitness.

Using eye-tracking technology in combination with highly controlled stimuli, the team found that pupillary responses to images of men and women appeared to be sex-specific but not sensitive to the sexual explicitness of the image.

Researcher Dr Janice Attard-Johnson said: 'We found that changes in pupil size when viewing images of men and women corresponded with participants' self-reported sexual orientation.

'This meant that in heterosexual men and women, dilation occurred during the viewing of opposite-sex people, but that these responses were comparable when participants viewed both naked and dressed targets.

'Our findings suggest that pupillary responses provide a sex-specific measure that is sensitive to both sexually explicit and non-sexually explicit content.'

Other research indicates that naked pictures of people elicit stronger signs of arousal than dressed images when this is measured using other physiological reactions, such as genital responses.

But researchers found this was not the case with pupillary responses, and suggest it is possible that a change in pupil size is elicited with lower levels of sexual arousal than is necessary for other physiological measures.