Emotions trigger facial expressions that harness useful light properties

Emotions filter our reality, says the team, and they shape what we see before any light actually reaches the inner eye.

Researchers say our eyes widen when we are fearful to allow more light and a wider visual field so that we can identify the cause of our fear.

Prof. Anderson says though we think of perception as a process that happens after the brain receives an image, “in fact emotions influence vision at the very earliest moments of visual encoding.”

The narrowing of the eye in disgust results in the greatest visual acuity, they note, which involves less light and better focus, whereas wide-eyed fearful expressions create the most sensitivity, allowing more light and a wider visual field.

“These emotions trigger facial expressions that are very far apart structurally, one with eyes wide open and the other with eyes pinched,” Prof. Anderson says, noting that this allows the eye “to harness the properties of light that are most useful in these situations.”

He and his team are currently studying how such contrasting eye movements could explain how facial expressions in humans have evolved to support nonverbal communication across different cultures.

“We know that the eyes can be a powerful basis for reading what people are thinking and feeling,” he says, “and we might have a partial answer to why that is.”

Speaking with Medical News Today, Prof. Anderson said:

“We are now examining how the optical origins of eye widening and narrowing in emotional expressions may now be used to communicate scrutiny or acceptance of ideas or people. For instance, we might narrow our eyes when scrutinizing an idea, as if to bring it into focus, or show wide-eyed acceptance of it.”

In 2013, we reported on a study that suggested oxytocin – “the love hormone” – has a self-perpetuating effect, whereby the hormone can make us fearful during future stressful situations if a social encounter is negative.