Measuring the Impact of Fearful Faces on Cognition
An unregulated amygdala can be frightening thing
DALLAS, Feb. 24, 2014 – As the brain’s primary structure for the formation of memories associated with emotional events – particularly frightening ones – the amygdala is also involved in the genesis of many fear responses, defensive behavior (so-called “fight or flight” reflexes), and other signals that directly influence the nervous system. Changes in blood pressure, heart rate and the release of stress hormones can all be triggered by the amygdala’s reaction to external stimuli.
In a healthy individual with normal level levels of anxiety, the amygdala operates in sync with the pre-frontal cortex, which acts as a governor on impulses that have been part of the human psyche since time immemorial, i.e., how we react to danger cues in our immediate environment and how we interpret certain threats or perceived threats.
Paul J. Whalen, Ph.D., a professor of psychological and brain sciences at Dartmouth College, spoke today on the role of the amygdala in recognizing fearful facial expressions, as part of the Center for Vital Longevity’s Brown Bag Science Luncheon Series. Dr. Whalen delivered his talk, “Neural responses to facial expressions predict attention, bias and personality,” to an audience of post-doctoral researchers, Center faculty and students, as well as guests from the Richardson campus, and UT Southwestern Medical Center.
Since beginning his studies at the University of Vermont, Dr. Whalen’s research has centered on role of the amygdala, with his latest research using facial expressions of emotion to test hypotheses about amygdalar function. Dr. Whalen presented behavioral, psychophysiological and imaging studies showing that fearful facial expressions spur reactions in those seeing them, often triggering increased attention and new learning.
The amygdala typically operates concurrently with processes in the pre-frontal cortex, Dr. Whalen said, which helps mediate the amygdala’s conversation with the nervous system, to allow increased anxiety responses when called for, and guard against unnecessarily elevated levels of anxiety when maladaptive. Through this dialogue between the amygdala and the cortex, the human brain can put into context what is being seen, in the case of Dr. Whalen’s research, the images of fearful faces used in his studies.
"Fear can be broadly characterized as uncertain negativity," Dr. Whalen said. "The amygdala notifies the cortex that this is an important instance to become more vigilant and learn, and the cortex in turn, decides on the proper course of action and updates the amygdala on its decision through a longer cognitive process."
In this way, the amygdala plays an important role in vigilance and priming the rest of the brain for learning, he said. The calculation of actual danger is not always accurate, however, especially in anxious individuals who may be experiencing what could be called a "hyper-vigilant" state that instantly creates a tonic change in the brain’s "readiness" to respond.
In many cases, with proper modulation and taking into account other factors (e.g., previous experience), the person observing a fearful face can empathize with the person showing fear, and seek to help someone who is facing what is ultimately a threat to that individual alone – a more appropriate reaction in certain circumstances.
The typical effect of looking at a fearful face, and the vigilance these faces induce, is to generally diffuse attention, where the subject looks for other information about a threat that cannot be gleaned from just the face alone.
By contrast, when presented with an angry face, the subject focuses attention on the individual alone, and whether he or she represents a real threat.
Therefore "anger tends to be certain negativity" that focuses attention in the onlooker, he said, and primes the body for action that may be key for survival in the moment.