Aggression - Neural and Hormonal Mechanisms (Studies)

Lab method - Ultimatum Game. 2 platers. Proposer offers to split money in a certain way w/ Responer. If R accepts, money split as proposed. If rejects, both receive nothing. Participants in this study played as Rs while having brain scanned by fMRI. 

Found when Rs rejected unfair offers, (aggressive reaction to social provocation) scan revealed fast and heightened response in amygdala.

Also found a benzodiazepine drug (reduses arousal of ANS) taken before game had 2 effects on responses to unfair offers:
   - halved number of rejections (reduced aggression)

   - decreased activity in amygdala

Strong evidence of assiocation between reactive aggression and amygdala activity

Drugs that increase seratonin activity also reduce lebels of aggressive behaviour

Gave participants either placebo or dose of paroxtine (enhances seratonin activity). Participants then took part in lab-based game - electric shocks of varying intensity given and received in response to provocation. 

Paroxetine participants consistently gave fewer and less intesne shocks than placebo group. However, only true of participants who had prior history of aggressive behaviour

Evidence of a link between seratonin function and aggression - beyond usual correlational findings

Measured changes in their male participants' T level before and after competitive game (which they all lost)

Once second sample taken, given choice:
    - challenge victorious opponent to another competition (aggressive)

    - complete unrelated task (non-aggressive)

Losers whose T levels rose after loss, 73% re-challenged. Losers T levels dropped, 22% re-challenged. 

After loss of status, behaved aggressively (choosing to re-challenge) only after increase in T levels. Confirm Mazur's BMoS, increasing its validity as plausable explanation of how T may exert its effects on aggression