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Stressed persons less goal-oriented: study- 30-Jul-2012
Psychologists from the Ruhr-Universitat and University Hospital Bergmannsheil in Germany have discovered that stressed persons are more likely to lapse back into habits than to behave goal-directed.
A team of Dr Lars Schwabe and Professor Dr Oliver Wolf from the Institute for Cognitive Neuroscience mimicked a stress situation in the body using stress hormones.
Data was collected from 69 volunteers divided into groups who received hydrocortisone, the stress hormone or just yohimbine, which ensures that the stress hormone noradrenaline stays active longer.
Some volunteers were administered both substances, and a fourth group were administered a placebo.
The study published in the Journal of Neuroscience found that the interaction of the stress hormones shut down the activity of brain regions for goal-directed behaviour.
The brain regions responsible for habitual behaviour remained unaffected.
In the experiment, all participants both male and female were told that they would receive cocoa or orange juice as a reward if they chose certain symbols on the computer.
They were allowed to eat as many oranges or as much chocolate pudding as they liked. "That weakens the value of the reward," Schwabe said.
"Whoever eats chocolate pudding will lose the attraction to cocoa. Whoever is satiated with oranges, has less appetite for orange juice," Schwabe said in a statement.
In this context, goal-directed behaviour meant whoever has previously eaten the chocolate pudding, chooses the symbols leading to cocoa reward less frequently. Whoever is satiated with oranges, selects less frequently the symbols associated with orange juice.
The volunteers who took hydrocortisone and yohimbine did not behave goal-directed but according to habit. In other words, satiation with oranges or chocolate pudding had no effect.
The brain data revealed that the combination of yohimbine and hydrocortisone reduced the activity in the forebrain in the so-called orbitofrontal and medial prefrontal cortex, associated with goal-directed behaviour.
Persons who had taken a placebo or only one medication, on the other hand, behaved goal-directed and showed a satiating effect.
