Jamil Zaki!

prosociality as reward-seeking!

Stanford University!

Jason Mitchell

self-interest prosociality

self-interest prosociality

! prosociality exhibits: !!   neural signatures of reward experience!!   behavioral patterns consistent with reward-seeking!

vMPFC!

OʼDoherty et al., 2003; de Araujo et al., 2003; Tom et al., 2007; Hare et al., 2008; !Knutson et al., 2003; McClure et al., 2004; Levy & Glimcher, 2011!

1: neural reward signatures!

1: neural reward signatures!

Tricomi et al., 2010!Fehr & Schmidt, 1999!Charness & Rabin, 2002!

OR!

$1.00 for! $1.33 for!

1: neural reward signatures!

OR!

$1.00 for! $1.33 for!

<!

1: neural reward signatures!

$2.50 for!

OR!

$2.00 for!

>!

1: neural reward signatures!

OR!

$1.00 for! $1.33 for!

<!

self-serving / inequitable!

1: neural reward signatures!

OR!

$1.00 for! $1.33 for!

<!

generous / equitable!

1: neural reward signatures!

$2.50 for!

OR!

$2.00 for!

>!

self-serving / equitable!

1: neural reward signatures!

Spitzer et al., 2007!

equitable > inequitable decisions!

Haber & Knutson, 2010!

1: neural reward signatures!

equitable > inequitable decisions!

Mbeta!

-1.5!

-1.0!

-0.5!

0.0!

0.5!self-serving / inequitable!generous / equitable!self-serving / equitable!

Zaki & Mitchell (2011), PNAS!

1: neural reward signatures!

2: behavioral signatures of reward-seeking!

$10.00!

or!

$18.00!

today! in 180 days!

2: behavioral signatures of reward-seeking!

$10.00!

or!

$22.00!

today! in 60 days!

2: behavioral signatures of reward-seeking!

$10.00!

or!

$14.00!

today! in 30 days!

self condition (n = 18)!

2: behavioral signatures of reward-seeking!

$10.00!

or!

$14.00!

today! in 30 days!

!“In this portion of the study, you are going to give an anonymous gift to the previous subject who participated in this experiment. This person will receive an Amazon.com (TM) gift code by email, and will be told that the choices of another participant led to them receiving this gift. However, they will not learn your identity, only that they are receiving a gift from “another participant.” Your choices will determine two things: WHEN the person receives this anonymous gift and HOW MUCH the gift code is worth.” !

gift condition (n = 17)!

2: behavioral signatures of reward-seeking!

$10.00!

or!

$14.00!

today! in 30 days!

!“In this portion of the study, you are going to make decisions about a reward that the last subject who participated in this experiment will receive. This person will receive an Amazon.com (TM) reward code by email. Your choices will determine two things: WHEN the person receives this reward and HOW MUCH the reward code is worth.” !

“fiduciary” condition (n = 20)!

2: behavioral signatures of reward-seeking!

0.0!

0.2!

0.4!

0.6!

0.8!

1.0!

0! 100! 200! 300! 400!

prop

(pat

ient

cho

ices

)

delay (days)

self!gift!fid!

0.000!

0.005!

0.010!

0.015!

0.020!

Neut! Gift! Self!

k!

Zaki & Mitchell (under review)!

2: behavioral signatures of reward-seeking!

self-interest prosociality

thanks!!

!   5 trials enacted!!   instructions:!

!   “One thing to keep in mind is that the other participant will have no knowledge that you performed this task. (S)he will simply receive an additional amount of money in addition to his / her base pay, and not be given information about the fact that this additional amount was determined by your decisions here.”!

1: neural reward signatures!

+$1.00 for

$1.00 for

$1.33 for

$1.33 fordecide!

fixation (1-6 sec)

offer (1.5-5 sec)

choice (2 sec)

other self

actual allocation

other

self

maximum possible allocation

generous/equitable

self-servinginequitable

generous/inequitable

self-servingequitable

ba

Figure 1

max allocation!

actual allocation!

gave 22% of total available money!

17%! 83%!

45%!55%!

1: neural reward signatures!

0!

0.2!

0.4!

-1! 0! 1! 2! 3!

inequitable > equitable!

Sanfey et al., 2003!inequitable!

choices!(proportion)!

inequitable – equitable (AI beta)!

Mbeta!

-0.5!

0.0!

0.5!

1.0!self-serving / inequitable!

generous / equitable!

self-serving / equitable!

r = -.64!p < .01!

Zaki & Mitchell (2011), PNAS!

x = 40!

1: neural reward signatures!