It seems that the brain much more quickly recognizes the emotion of fear than any other emotion, according to research conducted by Vanderbilt University. Although a smile gives a good first impression, fear makes a lasting one.
“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.”
Setting out to determine if our brain was aware of happy, neutral or fearful at the same speed, or if one of these emotions was processed quicker than another, the researchers needed to be able to slow down the information speed, usually less than 40 milliseconds. These high speeds make it impossible to get a good reading. They found that a technique being used in the lab of Randolph Blake, Centennial Professor of Psychology might just be what they needed to slow the facial recognition speed way down.
The technique, called continuous flash suppression, is able to keep people from becoming aware of what they are seeing for up to 10 seconds. With this the team was able to look through a viewer a lot like the eyepiece on a microscope that could allow different images to be presented to each eye.
One eye was presented with many images in rapid succession, while a stationery image was shown to the other eye. The multiple images suppressed the image of the face through a visual “noise” factor. Subjects stated that when they became aware of seeing a face at all, which allowed the researchers to determine if the expression on the face had any impact, they were first aware of the fearful expressions before the happy or neutral ones.
The report, appearing in the November 2007 edition of Emotion and co-authored by Eunice Yang, doctoral student, led researchers to believe that the area of the brain called the amygdale processes the information outside the visual information-processing center of the cerebral cortex. “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.”
Surprisingly, the 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.
The researchers will next explore how this information impacts 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?”
Pure Pedantry: The Function of Fearful Expression: http://scienceblogs.com/purepedantry/2008/07/the_function_of_a_fearful_expr.php
Future Pundit — Brain Scan Shows Fast Reaction To Fearful Face Pictures: http://www.futurepundit.com/archives/002537.html
Psysorg.com – People identify fearful faces before happy ones: http://www.physorg.com/news112026935.html