1) The study examined how the brain processes social and monetary rewards by conducting experiments where participants received positive or negative feedback about their reputation or monetary rewards. 2) The results found that both social and monetary rewards activated the striatum, a brain area involved in processing rewards. However, social rewards more strongly activated regions involved in mentalizing like the mPFC. 3) The findings suggest that a good reputation functions as a primary reward that is processed similarly to monetary rewards in the striatum, and gaining a positive reputation may motivate prosocial behaviors even without monetary incentives.

1. Processing of Social and Monetary
Rewards in the Human Striatum
K.Izuma et al. 2008 Neuron
Anna Jo
March 16th, 2010

2. Acquisition of one’s good reputation
=? Monetary Reward
Striatum:
Reward-related Brain area
“Common Neural Currency”
1) Both the anticipation and delivery of the reward (Schultz et al., 2000)
2) Increased activation in response not only to primary rewards such as
liquid or food (McClure et al.,2003) and sexual stimuli (Arnow et al., 2002)
but also to money, which is a secondary reward (Knutson et al., 2000)
3) To be modulated by the perception of the moral character (or reputation)
of others (Delgado et al., 2005)
4) Developing the reputation of other players during an economic game
(King-Casas et al., 2005)

3. How the brain processes One’s own positive reputation:
Social exchange theory
Good Reputation
Direct reward
Happiness Social Approval
=> A Hedonic => A Motivational
component of component of
Anticipated Reward Reward
“Liking” “Wanting”
reciprocity
Monetary Reward
Altruism and
Expected gain in
reputation and
perception of
influence on
efficacy
others
By Thibaut & Kelley 1959

4. Experiment Paradigm for
the Monetary Reward Experiment
[ Experimental Design ]
1. Participants: 19 subjects (9 male)
2. Each block consisted of eight
trials (24 s)
3. 20 blocks for each of the four
conditions [HMR, LMR, NoMR,
and fixation rest]
4. A total of four 8 min sessions

5. Experiment Paradigm for
the Social Reward Experiment
[ Experimental Design ]
1. A self-introduction phase + A
social reward acquisition phase.
2. the same 19 subjects were
presented with a picture of
themselves and a word or
phrase indicating the impression
of them
3. 84 were selected for the fMRI
experiment (42 items each for
the HSR and LSR conditions)

6. Behavioral Results
Monetary Reward Social Reward
• The mean reaction time : • HSR conditions more
1) HMR condition (490 desirable than LSR
ms) slower than NoMR conditions
condition (448 ms), • Happier in the HSR-Self
2) LMR condition (451 ms) condition than the LSR-Self
did not differ significantly condition
from the other two • The mean reaction time:
conditions. 1) NoSR condition (681 ms:
the fastest) / LSR condition
(1337 ms: the slowest)
2) Self condition (slower than
for the Other condition-HSR)

7. Imaging Results
Striatum Thalamus Cerebellum Monetary Reward vs. Social Reward
the left caudate nucleus and putamen
bilateral
caudate bilateral
nucleus putamen

8. Discussion
1. Uniquely activated by social rewards
2. Theory of mind (Gallagher and Frith, 2003), self-
reflection (Johnson et al., 2002; Kelley et al., 2002),
mPFC
and reflected self-knowledge (Ochsner et al., 2005)
3. mPFC involvement in self-reflection in the context
of attributions made by others

9. Discussion
One’s own reputation
OFC
A good reputation
=
A primary reward
Mid Monetary
Striatum Why do people
brain Reward
sometimes engage in
pro-social behaviors
while giving up
monetary benefits?
Insula
How and where the negative reward value of a bad
reputation is represented remains to be explored.