The Neural Basis of Economic Decision-Making in the Ultimatum Game (Science, 2003) PDF

REPORTS ide–sensitive factor) (33–35) or AP2 (36) may GluR2 carboxy-terminal peptide phosphorylated at 34. P. Osten et al., Neuron 21, 99 (1998). be required for export of functional heteromeric Ser880 as previously described (18). To accou...

REPORTS ide–sensitive factor) (33–35) or AP2 (36) may GluR2 carboxy-terminal peptide phosphorylated at 34. P. Osten et al., Neuron 21, 99 (1998). be required for export of functional heteromeric Ser880 as previously described (18). To account for the 35. I. Song et al., Neuron 21, 393 (1998). possibility that mutation of Lys882 interferes with the 36. S. H. Lee, L. Liu, Y.-T. Wang, M. Sheng, Neuron 36, 661 receptor complexes and/or stabilization of these recognition of phosphorylated Ser880 by this antibody, (2002). complexes at the cell surface. we purified polyclonal antiserum on an affinity column 37. Thanks to R. Bock for skillful technical assistance, K. Our results suggest that phosphorylation consisting of a bovine serum albumin (BSA)-conjugated Takamiya for advice on PCR genotyping, and mem- GluR2 carboxy-terminal peptide containing the K882A bers of the Huganir and Linden labs for helpful com- of GluR2 Ser880 is necessary for LTD induc- mutation (KVYGIEpS*VAI; pS* ⫽ phosphoSer880). ments. This work was supported by HHMI and USPHS tion. In Purkinje cells transfected with GluR2 26. N. Burnashev, H. Monyer, P. H. Seeburg, B. Sakmann, NS36715 (R.L.H.), USPHS MH51106 and MH01590 K882A, which presumably contain at least Neuron 8, 189 (1992). (D.J.L.) and the Develbiss Fund (D.J.L.). some GluR2 K882A/GluR3 and/or GluR2 27. Z. Jia et al., Neuron 17, 945 (1996). 28. M. I. Daw et al., Neuron 28, 873 (2000). Supporting Online Material K882A/GluR4c heteromeric receptor com- 29. C. H. Kim et al., Proc. Natl. Acad. Sci. U.S.A. 98: www.sciencemag.org/cgi/content/full/300/5626/1751/ plexes, the presence of a PKC consensus site 11725 (2001). DC1 30. M. Eto, R. Bock, D. L. Brautigan, D. J. Linden, Neuron Materials and Methods on subunits other than GluR2 appears to be 36, 1145 (2002). Fig. S1 insufficient to enable LTD. It is unknown 31. M. Ito, Physiol. Rev. 81, 1143 (2001). References whether the corresponding serines on GluR3 32. See supporting data on Science Online. and GluR4c are indeed phosphorylated by 33. A. Nishimune et al., Neuron 21, 87 (1998). 29 January 2003; accepted 6 May 2003 PKC or if upstream sequence differences and differential protein binding render these sub- units incapable of supporting LTD. Previous attempts to test the involvement The Neural Basis of Economic Downloaded from http://science.sciencemag.org/ on November 14, 2019 of cerebellar LTD in motor learning para- digms have relied on drugs or genetic manip- Decision-Making in the ulations that act early in the LTD induction signaling cascade, either at receptors or sec- ond messengers (1). These studies have been Ultimatum Game limited owing to the nonspecific nature of the Alan G. Sanfey,1,3* James K. Rilling,1* Jessica A. Aronson,2 manipulations (e.g., disruption of mGluR1 or Leigh E. Nystrom,1,2 Jonathan D. Cohen1,2,4 PKC function). A GluR2 K882A knock-in mouse could provide the first strong test of The nascent field of neuroeconomics seeks to ground economic decision- the hypothesis that cerebellar LTD is required making in the biological substrate of the brain. We used functional magnetic for certain forms of motor learning. resonance imaging of Ultimatum Game players to investigate neural substrates of cognitive and emotional processes involved in economic decision-making. In References and Notes this game, two players split a sum of money; one player proposes a division and 1. M. F. Bear, D. J. Linden, in The Synapse, W. M. Cowan, the other can accept or reject this. We scanned players as they responded to T. Sudhof, C. F. Stevens, Eds. ( Johns Hopkins, Balti- more, MD, 2000), pp. 455–517. fair and unfair proposals. Unfair offers elicited activity in brain areas related to 2. C. Hansel, D. J. Linden, E. D’Angelo, Nature Neurosci. both emotion (anterior insula) and cognition (dorsolateral prefrontal cortex). 4, 467 (2001). Further, significantly heightened activity in anterior insula for rejected unfair 3. F. Crepel, M. Krupa, Brain Res. 458, 397 (1988). 4. D. J. Linden, J. A. Connor, Science 254, 1656 (1991). offers suggests an important role for emotions in decision-making. 5. N. A. Hartell, NeuroReport 5, 833 (1994). 6. C. I. De Zeeuw et al., Neuron 20, 495 (1998). Standard economic models of human decision- Ultimatum Game. In the Ultimatum Game, two 7. J. H. Freeman, T. Shi, B. G. Schreurs, NeuroReport 9, making (such as utility theory) have typically players are given the opportunity to split a sum 2237 (1998). 8. J. Goossens et al., J. Neurosci. 21, 5813 (2001). minimized or ignored the influence of emotions of money. One player is deemed the proposer 9. M. Ito, M. Sakurai, P. Tongroach, J. Physiol. (London) on people’s decision-making behavior, idealiz- and the other, the responder. The proposer 324, 113 (1982). ing the decision-maker as a perfectly rational makes an offer as to how this money should be 10. D. J. Linden, M. H. Dickinson, M. Smeyne, J. A. Connor, Neuron 7, 81 (1991). cognitive machine. However, in recent years split between the two. The second player (the 11. D. J. Linden, Learn. Mem.(Cold Spring Harbor) 1, 121 this assumption has been challenged by behav- responder) can either accept or reject this offer. (1994). ioral economists, who have identified additional If it is accepted, the money is split as proposed, 12. K. Narasimhan, D. J. Linden, Neuron 17, 333 (1996). 13. D. J. Linden, Proc. Natl. Acad. Sci. U.S.A. 98, 14066 psychological and emotional factors that influ- but if the responder rejects the offer, then neither (2001). ence decision-making (1, 2), and recently re- player receives anything. In either event, the 14. S. Matsuda, T. Launey, S. Mikawa, H. Hirai, EMBO J. searchers have begun using neuroimaging to game is over. 19, 2765 (2000). examine behavior in economic games (3). This The standard economic solution to the Ulti- 15. Y.-T. Wang, D. J. Linden, Neuron 25, 635 (2000). 16. J. Xia, H. J. Chung,, C. Wihler, R. L. Huganir, D. J. study applies functional neuroimaging tech- matum Game is for the proposer to offer the Linden, Neuron 28, 499 (2000). niques to investigate the relative contributions of smallest sum of money possible to the respond- 17. S. Matsuda, S. Mikawa, H. Hirai, J. Neurochem. 73, cognitive and emotional processes to human er and for the responder to accept this offer, 1765 (1999). 18. H. J. Chung, J. Xia, R. H. Scannevin, X. Zhang, R. L. social decision-making. on the reasonable grounds that any monetary Huganir, J. Neurosci. 20, 7258 (2000). The limitations of the standard economic amount is preferable to none. However, consid- 19. J. L. Perez et al., J. Neurosci. 21, 5417 (2001). model are effectively illustrated by empirical erable behavioral research in industrialized cul- 20. H. Dong et al., Nature 386, 279 (1997). 21. P. Osten et al., Neuron 27, 313 (2000). findings from a simple game known as the tures indicates that, irrespective of the monetary 22. B. E. Kemp, R. B. Pearson, Trends Biochem. Sci. 15, sum, modal offers are typically around 50% of 342 (1990). the total amount. Low offers (around 20% of 23. Single-letter abbreviations for the amino acid resi- 1 Center for the Study of Brain, Mind and Behavior, dues are as follows: A, Ala; C, Cys; D, Asp; E, Glu; F, the total) have about a 50% chance of being 2 Department of Psychology, 3Center for Health and Phe; G, Gly; H, His; I, Ile; K, Lys; L, Leu; M, Met; N, Asn; Well-Being, Princeton University, Princeton, NJ rejected (4–8). This latter, quite robust, experi- P, Pro; Q, Gln; R, Arg; S, Ser; T, Thr; V, Val; W, Trp; X, 08544, USA. 4Department of Psychiatry, University of mental finding is particularly intriguing, dem- any amino acid; and Y, Tyr. Pittsburgh, Pittsburgh, PA 15260, USA. onstrating that circumstances exist in which 24. A. Y. Hung, M. Sheng, J. Biol. Chem. 277, 5699 (2001). *These authors contributed equally to this manu- people are motivated to actively turn down 25. We obtained polyclonal antiserum directed against a script. monetary reward. www.sciencemag.org SCIENCE VOL 300 13 JUNE 2003 1755  REPORTS Fig. 1. (A) Time line for a single round of the Ultimatum Game. Each round lasted 36 s. Each round began with a 12-s prep- aration interval. The partici- pant then saw the photograph and name of their partner in that trial for 6 seconds. A pic- ture of a computer was shown if it was a computer trial, or a roulette wheel if it was a con- trol trial. Next, participants saw the offer proposed by the partner for a further 6 s, after which they indicated whether they accepted or rejected the offer by pressing one of two buttons on participants saw five $5:$5 offers, one $7:$3 offer, two $8:$2 offers, a button box. (B) Behavioral results from the Ultimatum Game. These and two $9:$1 offers from both human and computer partners (20 are the offer acceptance rates averaged over all trials. Each of 19 offers in total). Why do people do this? The game is so a computer interface (Fig. 1A) (13). They com- right insula: t ⫽ 2.83, P ⬍ 0.05). This suggests simple that it is improbable that these rejec- pleted 30 rounds in all, 10 playing the game with that these activations were not solely a function Downloaded from http://science.sciencemag.org/ on November 14, 2019 tions are due to a failure to understand the a human partner (once with each of the 10 of the amount of money offered to the participant rules of the game, or an inability to concep- partners), 10 with a computer partner, and a but rather were also uniquely sensitive to the tualize a single-shot interaction with a part- further 10 control rounds in which they simply context, namely perceived unfair treatment from ner (9). On the basis of participant reports, it received money for a button press. The rounds another human (Fig. 2, C and D). Further, re- appears that low offers are often rejected were presented randomly, and all involved split- gions of bilateral anterior insula demonstrated after an angry reaction to an offer perceived ting $10. Offers made by human partners in fact sensitivity to the degree of unfairness of an offer, as unfair (10). Objecting to unfairness has adhered to a predetermined algorithm, which exhibiting significantly greater activation for a been proposed as a fundamental adaptive ensured that all participants saw the same set $9:$1 offer than an $8:$2 offer from a human mechanism by which we assert and maintain a (and a full range) of offers (14, 15). Half of these partner (Fig. 2E) (left insula, P ⬍ 0.001; right social reputation (11), and the negative emo- offers were fair, that is, a proposal to split the insula, P ⬍ 0.01), in addition to the aforemen- tions provoked by unfair treatment in the Ul- $10 evenly ($5:$5), with the remaining half pro- tioned greater activation for unfair offers than timatum Game can lead people to sacrifice posing unequal splits (two offers of $9:$1, two fair ($5:$5) offers. sometimes considerable financial gain in order offers of $8:$2, and one offer of $7:$3). The 10 Activation of bilateral anterior insula to un- to punish their partner for the slight. Unfair offers from the computer partner were identical fair offers from human partners is particularly offers in the Ultimatum Game induce conflict to those from the human partners (half fair, half interesting in light of this region’s oft-noted in the responder between cognitive (“accept”) unfair). The 10 control trials were designed to association with negative emotional states. An- and emotional (“reject”) motives, motives that control for the response to monetary reinforce- terior insula activation is consistently seen in we might expect to see represented in brain ment, independent of the social interaction. The neuroimaging studies of pain and distress (18– areas implicated in cognitive and emotional distribution of offers generally mimics the range 20), hunger and thirst (21, 22), and autonomic modes of thought, with additional regions pos- of offers typically made in uncontrolled ver- arousal (23). This region has also been implicat- sibly mediating these competing goals (12). sions of the game (i.e., involving freely acting ed in studies of emotion, in particular involve- To shed light on the neural and psycholog- human partners). ment in the evaluation and representation of ical processes mediating such behaviors, we Behavioral results were very similar to specific negative emotional states (24). Chief scanned 19 participants using functional mag- those typically found in Ultimatum Game amongst these are anger and disgust, both of netic resonance imaging (fMRI), each in the experiments (Fig. 1B) (16). Participants ac- which have been found to engage a distinct role of the responder in the Ultimatum Game. cepted all fair offers, with decreasing accep- region of the anterior insula activated by an We were interested in neural and behavioral tance rates as the offers became less fair. unfair offer in the present study (25, 26). reactions to offers which were fair (the money Unfair offers of $2 and $1 made by human Though studies of disgust have largely focused is split 50:50) or unfair (the proposer offered an partners were rejected at a significantly high- on physical sensations of taste and odor (27), it unequal split to his or her advantage). In par- er rate than those offers made by a computer has been suggested that emotion-based disgust ticular, we hypothesized that unfair offers ($9:$1 offer: ␹2 ⫽ 5.28, 1 df, P ⫽ 0.02; $8:$2 (as perhaps induced by an insultingly unfair would engage neural structures involved in offer: ␹2 ⫽ 8.77, 1 df, P ⫽ 0.003), suggesting offer) may be conceptually similar. The recruit- both emotional and cognitive processing, and that participants had a stronger emotional ment of similar neural structures, namely the that the magnitude of activation in these struc- reaction to unfair offers from humans than to anterior insula, in both physical and moral dis- tures might explain variance in the subsequent the same offers from a computer (17). gust gives some credence to this notion. decision to accept or reject these offers. Among the areas showing greater activation If the activation in the anterior insula is a Before scanning, each participant was intro- for unfair compared with fair offers from human reflection of the responders’ negative emotional duced to 10 people they were told would partner partners (Fig. 2, A and B; table S1) were bilateral response to an unfair offer, we might expect with them in the games to follow. They were told anterior insula, dorsolateral prefrontal cortex activity in this region to correlate with the sub- that they would play a single iteration of the (DLPFC), and anterior cingulate cortex (ACC). sequent decision to accept or reject the offer. game with each partner and that their decisions The magnitude of activation was also signifi- Because all fair offers and the vast majority of with each partner would not be revealed to the cantly greater for unfair offers from human part- $7:$3 offers were accepted, we focused on the other partners and, therefore, could not affect ners as compared to both unfair offers from $8:$2 and $9:$1 offers from a human partner for subsequent offers. The participants were then computer partners (left insula: t ⫽ 2.52, P ⬍ the analysis of whether neural activity was re- placed inside the MRI scanner and began play- 0.02; right insula: t ⫽ 2.2, P ⬍ 0.03) and low lated to the decision made in the game. Indeed, ing the Ultimatum Game with their partners via control offers (left insula: t ⫽ 3.46, P ⬍0.001; looking at the participant level, those partici- 1756 13 JUNE 2003 VOL 300 SCIENCE www.sciencemag.org  REPORTS Fig. 2. Activation related to the presentation of an unfair offer. (A) Map of the t statistic for the contrast [unfair human offer – fair human offer] showing activation of bi- lateral anterior insula and anterior cingulate cortex. Areas in orange showed greater activation follow- ing unfair as compared with fair offers (P ⬍ 0.001). (B) Map of the t statistic for the contrast [unfair human offer – fair human offer] showing activation of right dorso- lateral prefrontal cortex. (C) Event-related plot for unfair and fair offers in right anterior insula. The Downloaded from http://science.sciencemag.org/ on November 14, 2019 offer was revealed at t ⫽ 0 on the x axis. (D) Event- related plot for unfair and fair offers in left anterior insula. (E) Event-related plot for different human unfair and fair offers in subset of left anterior insula. pants with stronger anterior insula activation to that this region may be competing with emotion- unfair offers rejected a higher proportion of al areas in influencing the decision, we examined these offers (right insula: correlation coefficient the balance between activation in anterior insula r ⫽ –0.45, P ⫽ 0.025, one-tailed; left insula: and DLPFC for unfair offers. Unfair offers that r ⫽ –0.39, P ⫽ 0.05, one-tailed) (Fig. 3A). Of are subsequently rejected have greater anterior particular interest is whether these differences in insula than DLPFC activation, whereas accepted anterior insular activation extend to the trial offers exhibit greater DLPFC than anterior insula level. Looking across participants, an examina- (Fig. 3B). The contrast in activation between tion of individual trials also revealed a relation these two areas is significantly different for ac- between right anterior insular activity and the cepted and rejected offers (P ⫽ 0.033, one- decision to accept or reject (Fig. 3B). Activation tailed), consistent with the hypothesis that com- in this area was significantly greater in response petition between these two regions influences to unfair offers that were later rejected (P ⫽ behavior. DLPFC activity remains relatively 0.028, one-tailed). These results provide addi- constant across unfair offers, perhaps reflecting tional support for the hypothesis that neural the steady task representation of money maximi- representations of emotional states guide human zation, with anterior insula scaling monotonical- decision-making. ly to the degree of unfairness, reflecting the In contrast to the insula, DLPFC usually has emotional response to the offer. Caution is need- been linked to cognitive processes such as goal ed when comparing the magnitude of the fMRI maintenance and executive control (28, 29). signal across brain regions. However, it is inter- Thus, the DLPFC activation we observed in esting to note that the outcome of the decision response to unfair offers may relate to the rep- may reflect the relative engagement of these resentation and active maintenance of the cogni- regions, with greater anterior insula activation tive demands of the task, namely the goal of biasing toward rejection and greater DLPFC bi- accumulating as much money as possible. An asing toward acceptance. Finally, unfair offers unfair offer is more difficult to accept, as indi- were also associated with increased activity in Fig. 3. (A) Acceptance rates of unfair offers plotted against right anterior insula activation cated by the higher rejection rates of these offers, ACC. ACC has been implicated in detection of for each participant. (B) Right anterior insula and hence higher cognitive demands may be cognitive conflict (30, 31), and activation here and right DLPFC activation for all unfair offer placed on the participant in order to overcome may reflect the conflict between cognitive and trials, categorized by subsequent acceptance or the strong emotional tendency to reject the offer. emotional motivations in the Ultimatum Game. rejection. Although DLPFC activated to unfair offers, this This study sought to identify the neural cor- activation did not correlate with acceptance rates relates of fairness and unfairness, and in partic- sential to many aspects of societal and personal (r ⫽ 0.04, P ⬎ 0.05), suggesting that activation ular the relative contributions of cognitive and decision-making and underlies notions as di- of this region alone is not sufficient to predict emotional processes to human decision-making. verse as ethics, social policy, legal practice, and behavior. However, motivated by the hypothesis A basic sense of fairness and unfairness is es- personal morality. Our results are consistent with www.sciencemag.org SCIENCE VOL 300 13 JUNE 2003 1757  REPORTS the idea that the areas of anterior insula and they had been suspicious of the offers they received. suggests that subjects treated the Ultimatum Game as a DLPFC represent the twin demands of the Ulti- Further, the behavioral results in the human partner single-shot game, as instructed. condition replicate those found in versions of the game 17. We asked our participants as part of the debriefing matum Game task, the emotional goal of resist- using no deception, with approximately half of offers of process what they considered a “fair” offer to be ing unfairness and the cognitive goal of accumu- 20% or less of the total being rejected (9). Perhaps most irrespective of their decision to accept or reject, thus importantly, if subjects suspected deception, this should providing an indication of their standards of fairness. lating money, respectively. Further, our finding Of our participants, 58% considered any offer less have diminished emotional responses (i.e., if subjects that activity in a region well known for its in- suspected the offers to be fictitious, their emotional than $5:$5 as unfair, with the remaining 42% deem- volvement in negative emotion is predictive of reactions to these offers, particularly unfair offers, should ing anything less than $7:$3 to be an unfair division. have been muted). The fact that we observed significant 18. S. W. Derbyshire et al., Pain 73, 431 (1997). subsequent behavior supports the importance of 19. M. J. Iadarola et al., Brain 121, 931 (1998). effects consistent with emotional responses suggests, emotional influences in human decision-making. once again, that the effects of deception were minimal 20. K. C. Evans et al., J. Neurophysiol. 88, 1500 (2002). We believe that these findings, and work that and, if they were present, have simply caused an under- 21. D. Denton et al., Proc. Natl. Acad. Sci. U.S.A. 96, proceeds from them, will provide a more de- estimate of the observed effects. Although we are sensi- 5304 (1999). tive to the issue of deception, we believe that the meth- 22. P. A. Tataranni et al., Proc. Natl. Acad. Sci. U.S.A. 96, tailed characterization of specific emotional re- odological constraints of fMRI justified our practice and 4569 (1999). sponses, their neural substrates, and the social that the findings do not appear to be tainted by subjects’ 23. H. D. Critchley, R. Elliott, C. J. Mathias, R. J. Dolan, circumstances under which they are elicited. possible perceptions of the deception used. J. Neurosci. 20, 3033 (2000). 15. A common concern regarding the use of deception 24. A. J. Calder, A. D. Lawrence, A. W. Young, Nature Rev. Therefore, not only do our results provide direct Neurosci. 2, 352 (2001). involves possible contamination of the participant pool. empirical support for economic models that ac- As mentioned previously, rejection rates in the current 25. A. R. Damasio et al., Nature Neurosci. 3, 1049 (2000). knowledge the influence of emotional factors on study replicate those typically reported from uncon- 26. M. L. Phillips et al., Nature 389, 495 (1997). trolled Ultimatum Game studies; therefore, we do not 27. P. Rozin, A. E. Fallon, Psychol. Rev. 94, 23 (1987). decision-making behavior, but they also provide 28. E. K. Miller, J. D. Cohen, Annu. Rev. Neurosci. 24, 167 believe we suffered unduly from this. Furthermore, a the first step toward the development of quanti- comparison of rejection rates over the course of the (2001). Downloaded from http://science.sciencemag.org/ on November 14, 2019 tative measures that may be useful in constrain- experiment (i.e., longitudinally over participants) indi- 29. A. D. Wagner, A. Maril, R. A. Bjork, D. L. Schacter, cates no systematic trends in these rates (mean rejec- NeuroImage 14, 1337 (2001). ing the social utility function in economic mod- tion rate of offers for first six participants was 32%; 30. A. W. MacDonald III, J. D. Cohen, V. A. Stenger, C. S. els (32, 33). Models of decision-making cannot mean rate for last six participants was 35%). Carter, Science 288, 1835 (2000). afford to ignore emotion as a vital and dynamic 16. After the conclusion of the Ultimatum Game with all 31. M. Botvinick, L. E. Nystrom, K. Fissell, C. S. Carter, J. D. Cohen, Nature 402, 179 (1999). component of our decisions and choices in the partners, subjects then played a single round of the 32. E. Fehr, K. M. Schmidt, Q. J. Econ. 114, 817 (1999). real world. Prisoner’s Dilemma (PD) game with each of the partners. 33. G. E. Bolton, A. Ockenfels, Am. Econ. Rev. 90, 166 (2000). This raises the possibility that subjects did not treat the 34. R. Hertwig, A. Ortmann, Behav. Brain Sci. 24, 383 Ultimatum Game as a true single-shot game. We do not References and Notes (2001). believe playing the PD game affected their play in the 1. C. Camerer, G. Loewenstein, in Advances in Behavioral 35. S. Bonetti, J. Econ. Psychol. 19, 377 (1998). Ultimatum Game in this study for several reasons. First, Economics, C. Camerer, G. Loewenstein, M. Rabin, 36. We would like to thank D. Kahneman, A. Scheres, and our behavioral results support the notion that the Ulti- Eds. (Princeton Univ. Press, Princeton, NJ), in press. three anonymous reviewers for their helpful com- matum Game was played as a single-shot game. As noted 2. G. Loewenstein, J. Lerner, in The Handbook of Affec- ments. This work was supported in part by grants above, the proportion of rejected offers in our study tive Science, R. J. Davidson, H. H. Goldsmith, K. R. from the Seaver Institute and the Mind, Brain, Body, matches proportions reported in the experimental eco- Scherer, Eds. (Oxford Univ. Press, Oxford, 2003). and Health Initiative. nomic literature when the game is strictly controlled as 3. K. McCabe, D. Houser, L. Ryan, V. Smith, T. Trouard, single-shot. We would have expected much higher rejec- Supporting Online Material Proc. Natl. Acad. Sci. U.S.A. 98, 11832 (2001). tion rates in an iterated Ultimatum Game. Second, un- www.sciencemag.org/cgi/content/full/300/5626/1755/ 4. W. Guth, R. Schmittberger, B. Schwarze, J. Econ. published data of ours using a single-shot Ultimatum DC1 Behav. Organ. 3, 376 (1982). Game (with no subsequent task) produced rejection rates Materials and Methods 5. R. H. Thaler, J. Econ. Perspect. 2, 195 (1988). of unfair offers that are virtually identical to those re- Table S1 6. G. E. Bolton, R. Zwick, Game Econ. Behav. 10, 95 (1995). ported here ($8:$2 split, 47% versus 49%; $9:$1 split, 7. A. E. Roth, in Handbook of Experimental Economics, 61% versus 60%). We believe this evidence strongly 31 January 2003; accepted 15 April 2003 J. H. Kagel, A. E. Roth, Eds. (Princeton Univ. Press, Princeton, NJ, 1995). 8. See J. Henrich et al. [Am. Econ. Rev. 91, 73 (2001)] for Ultimatum Game research in simple societies. 9. C. Camerer, R. H. Thaler, J. Econ. Perspect. 9, 209 (1995). V1 Neurons Signal Acquisition of 10. M. M. Pillutla, J. K. Murnighan, Organ. Behav. Hum. Dec. Proc. 68, 208 (1996). 11. M. A. Nowak, K. M. Page, K. Sigmund, Science 289, an Internal Representation of 1773 (2000). 12. We use the term “cognitive” here, in place of the term “rational” (as commonly used in the traditional econom- Stimulus Location ic literature), in recognition of the fact that emotional responses may also have a rational basis (e.g., to punish Jitendra Sharma,1,2* Valentin Dragoi,1,2 unfair offers). The term “cognitive” is perhaps also prob- Joshua B. Tenenbaum,1 Earl K. Miller,1,2,3 Mriganka Sur1,2* lematic, for similar reasons. Terms such as “proximal” and “distal” may be more accurate, respectively indicat- ing the immediate and longer-term sources of gain A fundamental aspect of visuomotor behavior is deciding where to look or move associated with the behavior. However, until the field next. Under certain conditions, the brain constructs an internal representation converges on a new set of accepted terms for designat- of stimulus location on the basis of previous knowledge and uses it to move ing these classes of motivation, we use the terms cog- nitive and emotional as intuitively accessible, if not the eyes or to make other movements. Neuronal responses in primary visual technically accurate. cortex were modulated when such an internal representation was acquired: 13. Materials and methods are available as supporting Responses to a stimulus were affected progressively by sequential presentation material on Science Online. of the stimulus at one location but not when the location was varied randomly. 14. This methodology deviates somewhat from the standards of experimental economics, a field that generally pro- Responses of individual neurons were spatially tuned for gaze direction and scribes the use of deception [see (34) for a summary of tracked the Bayesian probability of stimulus appearance. We propose that the the issues, though there are some exceptions (35)]. We representation arises in a distributed cortical network and is associated with chose to use a limited amount of deception in the current study primarily because of the heavy logistic demands of systematic changes in response selectivity and dynamics at the earliest stages an fMRI study, requiring a full distribution of offers in a of cortical visual processing. constrained number of participants. Practical issues not- withstanding, we believe the use of deception had little if To assess whether monkeys (Macaca mu- information about future stimulus locations any impact on our results, and any effect was not likely to confound their interpretation. During the post-experi- latta) form an internal representation of stim- could be acquired progressively with succes- ment debriefing, no subject gave any suggestion that ulus location, we devised a task in which sive trials in one experimental condition but 1758 13 JUNE 2003 VOL 300 SCIENCE www.sciencemag.org The Neural Basis of Economic Decision-Making in the Ultimatum Game Alan G. Sanfey, James K. Rilling, Jessica A. Aronson, Leigh E. Nystrom and Jonathan D. Cohen Science 300 (5626), 1755-1758. DOI: 10.1126/science.1082976 Downloaded from http://science.sciencemag.org/ on November 14, 2019 ARTICLE TOOLS http://science.sciencemag.org/content/300/5626/1755 SUPPLEMENTARY http://science.sciencemag.org/content/suppl/2003/06/12/300.5626.1755.DC1 MATERIALS RELATED http://science.sciencemag.org/content/sci/300/5626/1673.full CONTENT REFERENCES This article cites 26 articles, 6 of which you can access for free http://science.sciencemag.org/content/300/5626/1755#BIBL PERMISSIONS http://www.sciencemag.org/help/reprints-and-permissions Use of this article is subject to the Terms of Service Science (print ISSN 0036-8075; online ISSN 1095-9203) is published by the American Association for the Advancement of Science, 1200 New York Avenue NW, Washington, DC 20005. The title Science is a registered trademark of AAAS. American Association for the Advancement of Science