| dc.description.abstract | Stress activates a variety of processes in the human body. An important example includes the activation of the HPA-axis which results in an increase of the stress hormone cortisol.
Besides this stress affects other parts and functions of the brain, amongst which the amygdala and prefrontal cortex that play an important role in the process of decision-making. This leads to the assumption that stress affects this process of decision making. This research-project addresses the question how and whether stress, activated by an acute social stressor, affects the process of long-term decision-making, i.e. the results achieved during the IOWA Gambling Task.
In order to generate stress, a variant of the Trier Social Stress Test has been used for the purpose of this research-project. This includes a task that the participant can only carry out by using its full "mental" abilities, which leads to a stress response that includes the activation of the HPA-axis. In order too check the reaction of the HPA-axis, cortisol samples are taken at several times during the experiment.
A number of 36 females participated and completed the experiment. The females were randomly divided in to two groups: the stress group (23) and the control group (13). Certain participants were excluded from the project in order to prevent any disruptions in a person's decision making ability in general or his or her balance of cortisol, dopamine, or serotonin through external factors. This includes: females with a psychiatric disorder, a BMI lower than 18 or higher than 24, as well as participants who used medication, drugs, or excessively used alcohol, nicotine or caffeine.
After 15 minutes of relaxation, the stress group started a +/- 15 minute Stress Test wherein they were exposed to acute social stress. Instead of this Stress Test, the control group spent another 15 minute period of relaxation. After this, both groups participated in the IOWA Gambling Task.
The differences in performance between the stress and control group during the IOWA Gambling Task resulted in several conclusions. First of all, the average cumulative budget per block of 20 trials between the two groups was compared. This showed that none of the five blocks significantly differed in terms of budget. Secondly, differences in the number of times participants in the stress or control group chose cards from the 'good' or 'bad' stacks per block of 20 trials were analyzed. This showed that there were no significant differences between the two groups in terms of selecting 'good' or 'bad' stacks of cards. However it appeared that participants who were exposed to the social stress of the Stress Test completed the IOWA Gambling Task (190,6 seconds) significantly faster with similar results as the control group (250,1 seconds). Lastly, the investigation results showed that the exposure to social stress did not lead to an increase of short term decisions, as was assumed at the start of this research project. | |
