| Abstract: |
In economic experiments decisions often differ from game-theoretic
predictions. Why are people generous in one-shot ultimatum games with
strangers? Is there a benefit to generosity toward strangers? Research on the
neural substrates of decisions suggests that some choices are
hormone-dependent. By artificially stimulating subjects with neuroactive
hormones, we can identify which hormones and brain regions participate in
decisionmaking, to what degree and in what direction. Can a hormone make a
person generous while another stingy? In this paper, two laboratory
experiments are described using the hormones oxytocin (OT) and arginine
vasopressin (AVP). Concentrations of these hormones in the brain continuously
change in response to external stimuli. OT enhances trust (Michael Kosfeld et
al. 2005b), reduce fear from strangers (C. Sue Carter 1998), and has
anti-anxiety effects (Kerstin UvnÃÂäs-Moberg, Maria Peterson 2005). AVP
enhances attachment and bonding with kin in monogamous male mammals (Jennifer
N. Ferguson et al. 2002) and increases reactive aggression (C. Sue Carter
2007). Dysfunctions of OT and/or AVP reception have been associated with
autism (Miranda M. Lim et al. 2005). In Chapter One I review past experiments
with the ultimatum (UG) and dictator (DG) games and visit some of the major
results in the literature. In Chapter Two I present the results of my
laboratory experiment where I examine why people are generous in one-shot
economic games with strangers. I hypothesize that oxytocin would enhance
generosity in the UG. Players in the OT group were much more generous than
those in the placeboâÃÂÃÂOT offers in the UG were 80% higher than
offers on placebo. Enhanced generosity was not due to altruism as there was no
effect on DG offers. This implies that other-regarding preferences are at play
in the amount of money sent but only in a reciprocal context. The third
chapter presents an experiment on punishment. I hypothesized that AVP would
increase rejections and stinginess in the UG and TG. Results show that AVP
affects rejections and stinginess in small groups but not in large ones.
Chapter Four contains the summary of future research suggestions. |