The next time you are wondering if somebody is listening to you, perhaps check out their eyes. A new study has found that our pupils dilate and constrict in sync with a speaker during the emotional moments of their speech. Their research can be read in full in the Journal of Experimental Psychology: General.
"Here we show that the eyes not only reveal the inner workings of one mind, but reveal when two minds connect," Thalia Wheatley, associate professor of psychological and brain sciences, said in a statement.
In the experiment, the researchers used infrared eye-tracking technology to track the pattern of participants' pupil dilation while they were shown eight films of people reading out an autobiographical story. Four of these were meant to pull on the heartstrings of the viewer, while the other four were emotionally neutral in tone. Meanwhile, they had a group of independent people listen to just the audio of the clip and rate on a sliding-scale how engaging they felt the narratives were.
The researchers then traced the points of the stories perceived to be the most interesting and saw how the viewers' pupil dilation patterns changed. The moments of high emotion saw all of the viewers' pupils dilate in synchronization with the speaker.
Most obviously, pupils dilate to adjust to the amount of light that enters the eye (like a shutter on a window). They also dilate as a physiological response to social, emotional, and even sexual stimuli, which cannot be consciously controlled. The study builds on the wealth of other research, and indeed old wisdom, that suggests the eyes can reveal a lot about the contents of a person's consciousness, mood, desires, and even perhaps their sexual orientation.
Wheatley added: "'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."