Are you all ears? Your eyes indicate if you are

Turns out, the eyes really are a window to the soul as a recent study has found that your pupils give away whether or not you are listening.

The Dartmouth research found that listeners are most likely to tune in when a speaker delivers the most emotional peaks of his/her narrative, as revealed by synchronous pupil dilation patterns of speakers and listeners due to shared attention.

The findings also demonstrated how empathy comes into play. While listeners with both high and low empathy tuned in for the climax of a story, overall, listeners with higher empathy tuned in more. Speakers who are highly expressive were more likely to evoke pupillary synchrony.

Most people know that pupils dilate to adjust the amount of light that enters the eye, but pupils also dilate rapidly in response to information that is being processed moment by moment.

The study measured engagement in real-time by evaluating a physiological response or in this case, pupil dilations, which cannot be faked or controlled consciously.

"'The eyes are the window to the soul' is an ancient saying supported by many scientific studies linking pupil dilation and eye gaze to mental states such as attention and intention. Here we show that the eyes not only reveal the inner workings of one mind, but reveal when two minds connect," said researcher Thalia Wheatley.

The study builds on the researchers' earlier findings demonstrating that pupil dilation patterns reflect the contents of consciousness or what one pays attention to. They plan to investigate their latest findings on pupillary synchrony further through a study using a dual infrared eye-tracker that can be used to track the dilations of a speaker and listener at the same time.

The findings appear in the Journal of Experimental Psychology: General.