People identify fearful faces before happy ones

October 19, 2007

A new study proves that the brain becomes aware of fearful faces more quickly than faces showing other emotions: a capability that may have evolved to direct attention to potential threats.

You may not be fully dressed without a smile, but a look of horror will make a faster first impression. Vanderbilt University researchers have confirmed what previous research had hinted at: the brain becomes aware of fearful faces more quickly than those showing other emotions.

"There are reasons to believe that the brain has evolved mechanisms to detect things in the environment that signal threat. One of those signals is a look of fear," David Zald, associate professor of psychology and a co-author of the new study, says "We believe that the brain can detect certain cues even before we are aware of them, so that we can direct our attention to potentially threatening situations in our environment."

People identify fearful faces before happy ones
Examples of the fearful, neutral and happy faces used in the experiment. Paul Ekman Group (

Randolph Blake, Centennial Professor of Psychology, and Eunice Yang, doctoral student, were co-authors of the study, which will appear in the November 2007 issue of Emotion.

The researchers set out to determine if we become aware of fearful, neutral or happy expressions at the same speed, or if one of these expressions reaches our awareness faster than the others. To do this, they needed to find a way to slow down the speed at which subjects processed facial information — which usually takes less than 40 milliseconds. At those high speeds it is difficult to tell which images rise to awareness the fastest.

Yang, the lead author of the study, realized that a technique being used in Blake's lab might provide a solution to the problem. The technique, continuous flash suppression, keeps people from becoming aware of what they are seeing for up to 10 seconds. Using this technique, the team had research subjects look at a screen through a viewer, similar to the eyepieces on a microscope, which allowed different images to be presented to each eye.

Many images were rapidly presented to one eye while a static image of a face was presented to the other. The multiple images served as visual "noise," suppressing the image of the face. The subjects indicated when they first became aware of seeing a face, enabling the researchers to determine if the expression on the face had any impact on how quickly the subject became aware of it.

The team found that subjects became aware of faces that had fearful expressions before neutral or happy faces. The researchers believe that a brain area called the amygdala, an area of the brain outside of the regions in the cortex that process visual information, may be responsible.

"The amygdala registers information about an image even before cortical areas involved in vision have finished their job. We think the amygdala has some crude ability to process stimuli and that it can cue some other visual areas to what they need to focus on," Blake says.

Zald and his colleagues believe the eyes of the fearful face play a key role.

"Fearful eyes are a particular shape, where you get more of the whites of the eye showing," Zald says. "That may be the sort of simple feature that the amygdala can pick up on, because it's only getting a fairly crude representation. That fearful eye may be something that's relatively hardwired in there."

A surprising finding was that subjects perceived happy faces the slowest. "What we believe is happening is that the happy faces signal safety. If something is safe, you don't have to pay attention to it," Zald says.

Next, the researchers will explore how this information influences our behavior. "We are interested in now exploring what this means for behavior," Yang says. "Since these expressions are being processed without our awareness, do they affect our behavior and our decision making? If so, how?"

The research was supported by funding from the National Institutes of Health. Blake and Zald are Vanderbilt Kennedy Center for Research on Human Development investigators.

Source: Vanderbilt University

Explore further: Can video games combat mental illness stigma?

Related Stories

Is your fear of radiation irrational?

July 14, 2015

Bad Gastein in the Austrian Alps. It's 10am on a Wednesday in early March, cold and snowy – but not in the entrance to the main gallery of what was once a gold mine. Togged out in swimming trunks, flip-flops and a bath ...

Fear discovery could lead to new interventions for PTSD

December 16, 2010

( -- Researchers at the University of Iowa have pinpointed the part of the brain that causes people to experience fear – a discovery that could improve treatment of post-traumatic stress disorder (PTSD) and ...

Researchers develop 'brain-reading' methods

July 27, 2009

It is widely known that the brain perceives information before it reaches a person's awareness. But until now, there was little way to determine what specific mental tasks were taking place prior to the point of conscious ...

Recommended for you

How the finch changes its tune

August 3, 2015

Like top musicians, songbirds train from a young age to weed out errors and trim variability from their songs, ultimately becoming consistent and reliable performers. But as with human musicians, even the best are not machines. ...

Machine Translates Thoughts into Speech in Real Time

December 21, 2009

( -- By implanting an electrode into the brain of a person with locked-in syndrome, scientists have demonstrated how to wirelessly transmit neural signals to a speech synthesizer. The "thought-to-speech" process ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.