Baumgartner et al. (2008)

Aim

To investigate the role of oxytocin following breaches of trust.

Participants

49 participants 

Method (2)

• Independent samples

• Laboratory experiment

Explain the instructions of the trust game (5)

• Participants played a social game called the “trust game”

Trust Game Instructions:

• An investor must decide whether they will keep a sum of money (e.g. $10) or share it with a trustee 

  • If the sum is shared, the investment is tripled ($30)

• Now, the trustee must decide whether they will repay the trust by sharing the gain with the Investor (so each gets $15) OR violate the trust by keeping the money 

• This game is built on the dilemma of either trusting or not trusting (trusting is profitable, but there are also risks)

• Participants were placed in an fMRI scanner study the role of oxytocin in creating trust throughout the duration of the game

Conditions (4)

• Control group:

  • placebo nasal spray 

• Experimental group:

  • oxytocin nasal spray

• The participants were then investors for several rounds and played the “trust game” with different trustees.

• In a second condition, they were told that they were going to play a "risk game" with a computer, instead of with another human being

Execution (3)

• Participants received feedback

  • They were told that their decisions resulted in poor investments because their trust had been broken

• After that, they were asked to make the next investment decisions

results (feedback-2, activity 1)

Feedback produced different results within the conditions:

• placebo group (affected)

  • more likely to decrease their rate of trust after being told that their trust had been broken

• oxytocin group (indifferent)

  • continued to invest at similar rates 

  • it did not matter to them that their trust had been broken

Activity in The Brain:

• oxytocin group

  • decreased response in the amygdala and caudate nucleus

    • Oxytocin reduces fear (via the amygdala) and shifts decision-making toward reward and positive feedback (via the nucleus accumbens), making people more willing to trust again

Implication (5)

• Oxytocin may facilitate the expression of trust, even despite it being violated, potentially lowering the defence mechanisms associated with social risk

• This occurs in the study when participants in the experimental condition ignored negative feedback

• These results only occurred during the human vs. human condition, rather than when the participants were against a computer player

  • Suggests that oxytocin’s effect on trust only comes into play in interactions with real people