¡Descarga Trust and Oxytocin: The Neuroscience of Cooperation and Social Interactions y más Apuntes en PDF de Economía solo en Docsity! Lecture 15 – Trust Trust Game -‐-‐-‐ There is an Investor and a Responder. The Investor is given $10 and is allowed to give as much as he wants to the proposer. Any amount that he gives will be tripled. The proposer then can return as much as he wants to the Investor. Again, egoistic agents should not give back any money to investors, and again, experimental evidence goes against that idea. Most investors are keen to give at least half of their money, and most of proposers do return money to investors. Propensity to trust (proportion of the initial endowment that is sent to the responder by the investor) Propensity to reciprocate (ratio between the amount returned and the amount sent by the investor) The backward solution of the game is that the responder will not give any money back to the investor, and by consequence the investor will not give any money to the responder (Nash Equilibrium). OXYTOCIN increases trust in humans. Trust is one of the strongest predictor of a nation’s wealth. Experiment: Subjects play the trust game against a human opponent and a computer program which, they were told, would play a human-‐like strategy (monitored by magnetic resonance) Findings • Subjects are more likely to cooperate with human being than with computers • Co-‐operators have significantly different brain activation in the two conditions • The six subjects with the highest cooperation scores show significant increases in activation in medial prefrontal regions during human-‐human interactions when compared with human-‐ computer interactions. • The six subjects who received the lowest cooperation scores (22, 10, 18, 21, 11, and 3) did not show significant activation differences in medial prefrontal cortex between the human and computer conditions. • Behavioural data shows that half the subjects in our experiment consistently attempted cooperation with their human counterpart. • Within this group, and within subjects comparison, they find that regions of prefrontal cortex are more active when subjects are playing a human than when they are playing a computer following a fixed (and known) probabilistic strategy. Within the group of non-‐cooperators, we find no significant differences in prefrontal cortex between the computer and human conditions. • One possible explanation for our results is that within this class of games, subjects learn to adopt game form-‐dependent rules of thumb when playing the computer or when playing non-‐cooperatively with a human counterpart. • Cooperation requires an active convergence zone in prefrontal cortex, that binds joint attention to mutual gains with the inhibition of immediate reward gratification to allow cooperative decisions. Comparison between rational and emotional area of the brain. System 1 and system 2 are never alternative objects. They are always activated together but one is more activated than the other. A picture of our brain 1.5 seconds before showing the results; for seeing if the player 1 thinks about player 2 behaviour or not. Cooperation à one reason is altruism, but the other reason is that we need other people for getting more. So even rationality can explain a trusting behaviour. Findings: • Subjects were more likely to cooperate with real humans than with computers. • The brain region activated is different in the two cases. • Dominant strategies are strong in rational behaviour, but at the same time our mind is more complicated than this. • System 2 can decide both to trust and not to trust. To trust can be a rational solution. Cooperation requires an active convergence zone in prefrontal cortex OXYTOCIN AND TRUSTING BEHAVIOUR Women are more risk averse than man, and women reciprocate more than men. In women oxytocin is produced in larger quantities. EXP with placebo effects à oxytocin causes a general increase in pro-‐social inclinations. Oxytocin affects trust. BETRAYAL (tradimento) AVERSION • Oxytocin helps subjects to overcome their betrayal aversion in social interactions. • The reason of trusting under a dose of oxytocin is not that you aspect the other gives you back the money. You trust more because your fear to be betrayed is less controlled.
