Looking scared could be protective

“Fearful faces 'spot threats better'” is the headline on Channel 4 News. The Observer also reported on the same study at the weekend, claiming that a team of Canadian neuroscientists had solved the evolutionary mystery of why our faces contort in a certain way when we are scared.

The researchers found that when a group of students were told to make their eyes bulge or nostrils flare to mimic the facial expressions of fear, their ability to sense danger improved more than when they mimicked the face of disgust. This, the researchers say, supports Darwin’s 1872 idea that facial expressions of emotion are often remarkably similar across human cultures, and even the animal kingdom, implying they may have a common evolutionary benefit. The researchers say that their experiment shows how a fearful expression is a protective one rather than a social one because it increases the range of vision, speeds up eye movement and improves airflow through the nose.

It is not clear how the facial expressions of fear or disgust might affect the selection processes that form the basis of evolutionary theory. However, the results of this testing demonstrate a plausible sequence of events for how selection might occur.

Where did the story come from?

Dr Joshua M Susskind and colleagues from the Department of Psychology, University of Toronto in Canada carried out this research, supported by a Canada Research Chairs program and a Natural Sciences and Engineering Research Council grant. It was published in the peer-reviewed science journal Nature Neuroscience .

What kind of scientific study was this?

This was an experimental study. Using computer-generated graphics, the researchers trained a group of undergraduate students to model a set of facial expressions and then tested their vision and the airflow through their nose.

During the training, the participants were presented with facial examples from one of eight different individuals, four men and four women, displaying six different emotional expressions. They used pictures of faces showing anger, disgust, fear, happiness, sadness and surprise. After the participants rated these faces to identify which type of expression was shown, they were then asked to perform the face themselves. For fear, they were asked to furrow the brow by contracting the muscles, widen the eyes and flare the nostrils. For neutral expressions, they were asked to relax their muscles.

In separate experiments, with up to 20 participants each time, the researchers checked their ability to perform various tasks and took some measurements. They checked the visual fields by assessing how well the participants could see objects at the periphery of their vision, and by tracking participants’ eye movements. The researchers also used a respiratory device with a mask attached to a computer to measure how well the participants could breathe through the nose and to record the volume of air inhaled each minute. They also used MRI scans to take images of the nasal passages and this allowed them to estimate the volume of air within the nose by counting the number of pixels contained in the image of the passages on the screen.

They repeated the same tests when the participants were asked to show disgust. This face type was closest to the opposite of fear, with narrowed eyes, raised lips and a narrow nose.

What were the results of the study?

The researchers say, “When subjects posed expressions of fear, they had a subjectively larger visual field, faster eye movements during target localisation and an increase in nasal volume and air velocity during inspiration.” The opposite pattern was found for disgust.

What interpretations did the researchers draw from these results?

The researchers suggest that fear may enhance perception, whereas disgust dampens it. These results provide support for the Darwinian theory that facial expressions are not tools for social communication, but may have originated as a means of changing our interaction with the sights and smells of the physical world.

What does the NHS Knowledge Service make of this study?

This study has examined the idea that expressions not only signal emotions, but may have originated to prepare us for perception and action. This is the basis for one of Darwin’s principles about facial expressions. By showing that fear and disgust were recognised by volunteers as opposite expressions, and that they also had opposite effects on some measures of vision and smell, the researchers have added to the debate.

This was a small study and, as the researchers say, it focused on a subset of expressions. There is still the possibility that expressions other than fear and disgust have a role to play in selection pressures.
All researchers and participants were aware of the purpose and goals of the testing and this may have affected responses. People were asked to open their eyes and flare their nostrils; therefore, it is not surprising that differences appeared in objective testing.
This study has tried to replicate the facial expressions of various emotions, including fear and disgust. It is not clear whether these findings are representative of what happens in people truly experiencing these emotions. Even if these findings do represent the true effects of fear on facial expressions, it is not clear whether the improvements in sensory perception brought about by these expressions would have a significant effect on a person’s ability to survive the fearful event – and therefore whether they would give the person a “selection advantage”.

Sir Muir Gray adds...

I have referred this to my image consultant and face coach.