The authors' previous work involving the task has shown that it takes study subjects longer to identify the correct expression when the expression and word contradict one another. But the slowdown in reaction time is lessened if the previous image was also incongruent, demonstrating that an emotion regulatory process kicked in to help the brain react faster to the conflicting emotional information. "We can see through the reaction-time effect that people are adapting their emotional processing" from image to image, Etkin explained.
In the current study, Etkin and his colleagues found that both healthy participants and GAD patients were able to identify the expressions. Healthy participants, as was expected, reacted more quickly to incongruent images when the previous image was also incongruent. When later asked if they were aware of any pattern that might have helped or hindered their performance, the volunteers said they were not; Etkin said this demonstrated that this process was carried out unconsciously.
However, the researchers found that in the GAD patients, the reaction-time effect seen in healthy patients was absent and in the most anxious patients, reaction time actually worsened when there were two incongruent images in a row. "GAD patients had decreased ability to use emotional content from previous stimuli to help them with the task," said Etkin.
He said the differences between the two groups were striking. "By looking at reaction times alone, we could classify who was a patient and who was a control," he said, adding that this represented the first solid demonstration that a psychiatric population has a deficit in a form of unconscious emotion regulation.
Earlier work from Etkin and colleagues had shown that when healthy subjects encountered the emotional conflict during this task, the pregenual anterior cingulate, a part of the b
|Contact: Michelle Brandt|
Stanford University Medical Center