Unsure if your beloved really loves you this Valentine’s Day? Well just look deep into their eyes for the answer, according to new research by the University of Essex.

Researchers have for the first time proved that pupil dilation and sexual arousal are 100 per cent linked after carrying out simultaneous testing during a study.

Published in the Biological Psychology journal, the study will help develop new methods of understanding and testing sexuality which are less invasive and, therefore, more likely to attract a broader and more diverse range of participants.

The study, led by Dr Gerulf Rieger from the Department of Psychology, looked into whether pupil dilation was a precise indicator of the physiological responses linked to sexual arousal.

The scientists recruited 76 men and 72 women of various ages and ethnicities who indicated their sexual orientation on a seven-point scale. They were tested for sexual arousal and eye movements while watching videos which included sexual content.

The results showed a precise link between the volunteers’ sexual orientation with the reactions of their pupils and their bodily responses.

Dr Rieger said: “Sexual attraction and arousal are a fundamental part of human nature – without them we would not exist because we could not mate. Yet, we know so little about them because in the past most people have been reluctant to participate in studies on sexual arousal.

“With our new measure we found a truly novel way of telling somebody’s sexual arousal. Moreover, because our pupils dilate automatically, we have discovered a way of assessing somebody’s arousal that does not rely on what participants are willing or able to tell.”

A new eye-tracking laboratory is currently being built at Essex to verify whether pupil dilation can fully replace the previous methods of assessing sexual arousal.

Dr Rieger and his team are also looking into using their non-intrusive methods to investigate sexuality among other cultures.

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Note to editors

For more information or to interview Dr Gerulf Rieger please contact the University of Essex Communications Office on 01206 872400 or email comms@essex.ac.uk. A photo of Dr Rieger is available to download from our Flickr account.