Altruism & the Brain

transcript

Dharol Tankersley Cognitive Affective and Social Neuroscience January 23, 2007

Neural Mechanisms of

Altruism

Dharol Tankersley Department of Philosophy Brain Imaging and Analysis Center

Other-Regarding Preferences

• Altruism • Social Reward • Social Preference

Overview

Ø  I. Other-Regarding Preferences Ø  II. Social Reward

Ø  Experiment 1: Altruism & Social Reward Processing

Ø  III. Social Perception

Ø  Experiment 2: Altruism & Social Perception

I. Preference

< “Preference”

Preference –  Psychological mechanism of choice –  Inferred from behavior

“Altruism”

Types of preference

¬ Self-Regarding ¬ Other-Regarding

Preference to help/ harm others at personal cost

Preferences are utility maximizing

Homo Economicus Homo Altruisticus

Revealing other-regarding preferences

Trust Game

Coop Defect

Defect

2,2 3,0

1,1 0,3

Prisoner’s Dilemma

P1 - 10

Ultimatum Game

Accept

Unfair

Reject

0,0 0,0

Coop Defect

P1 - 40

Dictator game

P1 - 10

Individual differences

p  Pleasure

n Choice frequency

Homo Economicus Homo Altruisticus

Overview

“Reward Regions”

II. Neural Mechanisms of Social Reward

•  King-Casas et. al., Science 2005

Trust Punishment

•  Moll et. al., PNAS 2006

•  Rilling et. al., Neuron 2002

P1 20,20

15,30 P2

•  de Quervain et. al., Science 2004

10,20 Cooperation

Giving

2,2 3,0

1,1 0,3

Experiment 1

•  Hypothesis:

Differences in striatum activity during receipt of personal and charitable rewards will be smaller for subjects with strong ORPs than for subjects with weak ORPs

E1: Overview Charity Selection Task Survey

American Red Cross

Easter Seals – United Cerebral Palsey

Animal Protection Society

Durham Literacy Center

Charity Selection Task Survey • Local • Apolitical • Varied

Subject Charity

Recipient

Charitable Reward

Personal Reward

Altruistic Action

Selfish Action

Charity Selection Task Survey

You will play for Easter Seals +

Easter Seals

wins a Dukat!

will play for

Easter Seals

a Dukat!

A priori cluster analysis

1. I have helped push a stranger’s car out of the snow.

12. I have given a stranger a lift in my car.

4. I have given money to a charity.

5. I have given money to a stranger who needed it.

19. I have offered my seat on a bus or a train to a stranger who was standing.

Tree Diagram for 21 VariablesSingle Linkage

Euclidean distances

V21V10

V17V12

V14V19

V18V16

[Playing > Watching]

Right Striatum 0.40%

15s 0s

) Trial

Onset q  Charitable Reward q  Personal Reward q  Selfish Action q  Charitable Action

Individual differences in ORPs tracked by striatum

•  Moll et. al., PNAS 2006 •  Harbaugh et. al., in progress

Frequency of donation correlates with BOLD response to donations in striatum.

Striatal activation during receipt of money inversely predicts activation during donation.

Right STC .15%

-0.15% B

Trial Onset

15s 0s

q  Charitable Reward q  Personal Reward q  Selfish Action q  Charitable Action

[Watching > Playing]

lSTC PCC

Saxe & Kanwisher, NeuroImage 2003.

[Theory of Mind]

Saxe & Wexler, Neuropsychologia 2005.

[Belief Attribution]

Z = 24 X = 4

Y = –60

Subject-receiving Charity-receiving

SRAS scores predict pSTC activity

pSTC signal (Δ%) by altruism (z-score)

–0.25%

r = 0.57, P = 0.002

Low altruism

High altruism

– 0.15

Agency attribution and altruism

•  pSTC

•  Task

Agent Goal Help

Overview

n  Low-level visual perception n  Target detection n  Oddball

n  Social Perception n  Theory of Mind n  Goal detection

III. Social Perception Mechanisms

n  pSTC coordinates for E1

pSTC tasks

Castelli et. al., Neuroimage 2002

Saxe et al Neuropsychologia 2004

Vollm et al NeuroImage 2006

Aichorn et al NeuroImage 2005

Intention attribution

Goal attribution

Mental state detection

Perspective taking

Altruism & pSTC

Altruism

pSTC Empathy

•  Hypothesis 1: Differences in striatum activity during receipt of personal and charitable rewards will be smaller for subjects with strong ORPs than for subjects with weak ORPs

•  Hypothesis 2:

Differences in right pSTC activity during Watching trials will be greater for subjects with strong ORPs than for subjects with weak ORPs - Exploratory: Other traits might mediate

E2: Overview

•  Blocked Design

•  Control Condition

•  Graphics

Charitable Reward

Personal Reward

Altruistic Action

Selfish Action Control

+ will play for

will play for

•  Impulsivity: BIS

•  Empathy: IRI •  Personality: NEO •  Helping Behavior: SRAS & PAL •  Fairness: (Allocation)

PAL Scale

OFC Right pSTC

pSTC signal (ΔPE) by PAL (z-score)

r = 0.57, P = 0.01 –2

High altruism

Low altruism

pSTC activity specific to altruism

STC Models

“Biological”… or “Meaningful”?

Pelphrey et al. Cerebral Cortex, 2005.

Pelphrey et. al. J Neurosci 2003.

STC: “Meaning” vs. Movement

“Disposition or movements of an animate object (agent) relative to a part of the environment (goal or object of the action).”

Perrett et al. J Exp. Biol. 1989.

Goal-Centered ↑

Object-Centered ↑

Viewer-Centered •  Combinatorial representation

Precursor mechanism

• Empathy • ToM

•  Imitation

•  Emotion

Blair, Consc. & Cog., 2005.

Allison et al., Cog Sciences., 2003.

Summary

•  ORPs explain variation in helping behavior

•  Reward regions might track ORPs

•  Individual differences in altruism exist in

early perceptual processing

Future directions

•  Development

•  Individual differences in sensitivities to various types of social reward

http://img.photobucket.com/albums/v335/Pila14/kindness.jpg

Acknowledgments Co-authors on Manuscript •  Jill Stowe •  Scott Huettel Assistance in Data Collection •  Erin Douglas •  Steve Green

Comments on Manuscript and Research •  Greg McCarthy •  Jamie Morris •  Kevin Pelphrey •  Dale Purves •  Bethany Weber

External support •  NIMH R01-70685 •  NINDS P01-41328 (Project 2)

DOI: 10.1038/nn1833

Altruism & the Brain

Health & Medicine