CENTENNIAL HONORS COLLEGE
Western Illinois University
Undergraduate Research Day 2015
Poster Presentation
Can you trust a stranger? Choices during the Prisoner’s Dilemma and Snowdrift Dilemma
Ariel Wilson
Faculty Mentor: Sandra McFadden
Psychology
Knowledge about the neural basis of choices made during social dilemma tasks is limited. Previous
research has focused on two choices, cooperation and defection, made during a social dilemma task called
the Prisoner’s Dilemma (PD). EEG activity recorded from the prefrontal cortex showed different patterns
of activation for the two choices, with greater beta (12-24 Hz) and gamma (>25 Hz) activity during
defection choices. The present study extended previous research by using an additional social dilemma
task, called the Snowdrift Dilemma, and a different method of recording EEG activity called
hyperscanning. Undergraduate students played the two games in pairs, while EEG was recorded. EEG
data for cooperation and defection choices were analyzed separately. Participants’ reactions were also
analyzed based on outcomes. We expected more cooperative choices in Snowdrift versus PD, and greater
alpha (8-12 Hz) activity and lower beta activity during cooperative choices versus defection. Results
showed greater alpha activity and lower beta activity for cooperative choices, as predicted. Pairs who
cooperated the most frequently had the highest levels of alpha activation. The EEG results indicate that
fewer cognitive resources are required for cooperation than for defection. In future studies it will be
interesting to compare different groups (e.g., people with and without depression or ADHD) to explore
differences in social interactions.