Washington, Mar 20 : Researchers at Stanford have used 'disgusting videos' to study two coping methods the brain uses to regulate human emotions.
For the study, male subjects were shown 15-second videos that were intended to produce 'disgust' and functional magnetic resonance imaging (fMRI) was used to examine and measure the nervous system in the brains of subjects.
Led by Philippe Goldin, a Stanford research associate in psychology, the researchers contrasted two techniques of emotion regulation; that is, the way that humans cope with and control their emotions and feelings.
The researchers found that one method, cognitive reappraisal, reduced the intensity of negative emotions the participants experienced when exposed to videos of disgusting images.
"For example, if you were watching a doctor stitch up a wound in someone's arm, rather than just being horrified by all the blood, you might instead focus on the fact that the patient was being helped and would recover," Goldin said.
The other method is called expressive suppression. It, instead, actually increased the intensity of negative emotions but the subject tries to outwardly act like everything is ok.
In this method, the subject simply suppresses all physical and emotional feelings and 'you grit your teeth and bear it.'
In the study, the participants were taught both techniques. During the experiment, the subjects lie down inside the MRI scanner, which shows neural activity in the brain while they viewed various 15-second video clips on a screen 6 inches from their face.
A camera poised next to the video screen recorded their facial expression, capturing their every twitch and grimace. Participants also rated how they felt immediately after viewing each clip.
James Gross, associate professor of psychology and senior author of the paper, said that some of the clips were very disgusting in nature, showing scenes of 'surgical procedures, vomiting and animal slaughter.'
"In order to understand what happens when people control intense emotions in everyday life, we needed to induce potent emotions in the scanner so that we could see what parts of the brain are activated both by the emotion itself and by the efforts to regulate that emotion," Gross said.
The researchers found that the amygdale and the insula, two regions of the brain that are involved with reactions and emotions, contained the most activity when viewing the disgusting scenes.
However, the study showed that the amount of activity of these two brain areas differed depending on which technique, cognitive reappraisal or expressive suppression, was used by the subjects to cope with their emotions.
Cognitive reappraisal reduced negative emotions of the subjects very quickly. However, expressive suppression caused an increase in the neural activity within the amygdale and insula.
Therefore, the study concluded that only cognitive reappraisal helped participants reduce their emotional reactions to the disgusting scene. Expressive suppression caused more stress in the subjects.
"These two forms of regulation work quite differently. Early forms of [cognitive] regulation, such as reappraisal, effectively shut down the emotion at relatively little cost," Gross said.
As for expressive suppression, Gross said: "Although you can look cool as a cucumber, you actually get physiologically even more activated than you would have been if you had just let the emotion play itself out."
The study is published in the March 15 issue of Biological Psychiatry.