In social decision-making, people care both about others' outcomes and their intentions to help or harm. How the brain integrates representations of others' intentions with their outcomes, however, is unknown. In this study, participants inferred others' decisions in an economic game during functional magnetic resonance imaging. When the game was described in terms of donations, ventromedial prefrontal cortex (VMPFC) activation increased for inferring generous play and decreased for inferring selfish play. When the game was described in terms of individual savings, however, VMPFC activation did not distinguish between strategies. Distinct medial prefrontal regions also encoded consistency with situational norms. A separate network, including right temporoparietal junction and parahippocampal gyrus, was more activated for inferential errors in the donation than in the savings condition. These results demonstrate that neural responses to others' generosity or selfishness depend not only on their actions but also on their perceived intentions.

Although we examined activation across the whole brain, our key hypotheses related to activation in the VMPFC. Evaluating others' decisions might recruit the VMPFC in three possible ways. First, the VMPFC might represent only the value of personal outcomes. In this case, its activation should not distinguish between any observed outcomes, since participants had no personal stake in the game. Second, the VMPFC might “simulate” the objective value of others' outcomes regardless of how they are described. In this case, since the observed monetary payoffs were identical between conditions, any VMPFC activation should be also identical between conditions. Finally, VMPFC activation might reflect preferences about others' outcomes that incorporate their perceived intentions. In this case, its activation should represent the value of players' contributions in the Donation condition (when those contributions affected players' perceived intentions to help or harm others), but not in the Savings condition (when they did not).

In both conditions, participants on each trial inferred how much they expected the group of players to contribute (in the Donation condition) or save (in the Savings condition). Next, they saw each player's actual contribution amount. In the Donation condition, “High” (compared with “Low”) inferences corresponded to high contributions and hence larger monetary outcomes for the group; in the Savings condition, “High” inferences corresponded to high individual savings and hence larger monetary outcomes for some individual players but not the group. The objective monetary outcomes were identical across conditions, and participants had no personal monetary stake in the game in either condition. The effect of the task descriptions on players' perceived intentions was measured by examining changes in liking for players (in the FMRI study) and interpersonal perceptions of players (in the behavioral study). If the different descriptions suggested different intentions behind the same observed actions, then participants should report increased liking for generous players and decreased liking for selfish players in the Donation condition, but not in the Savings condition.

To test whether VMPFC activation reflects both others' outcomes and their intentions, we examined participants in an event-related functional magnetic resonance imaging (FMRI) study, as well as a separate behavioral study, while they observed other people playing a repeated public goods game () framed with one of two different descriptions ( Figure 1 ). In both versions of the observed game, each player on each trial decided how much of a $10 endowment to contribute to a group investment, which was then doubled and split equally between players. The game presents a tension between contributing, which benefits the group, and not contributing, which benefits the individual player. In the “Donation” condition, the game was described in terms of donations and the group consequences of generous or selfish play. This description was designed to evoke emotional responses to players' actions, and to highlight players' helpful or harmful intentions toward others (). In the “Savings” condition, the game was described in terms of personal savings and the individual consequences of risky or prudent play. This kind of description reduces personal contributions in the public goods game and related social dilemmas () and was designed to minimize emotional judgments about players' intentions toward others.

Participants observed and made inferences about other players in a repeated public goods game. Participants did not play themselves and had no personal monetary stake in the game. In the observed game, each player on each trial decided how much of a $10 endowment to contribute to a group investment that was then doubled and split equally between players on that trial. On each trial, participants first saw the four players for that round (face phase, 8 s), then inferred whether their contributions would total $20 or more (“High”) or less than $20 (“Low”; inference phase, 3-5 s). Each player's actual contribution was then displayed under her face, along with the total contribution and the correct outcome (feedback phase, 5 s). A Donation-condition trial is shown; the Savings condition was identical except all inferences and feedback were in terms of savings ($10 – the contribution amount) rather than contributions.

Neural correlates of social preferences are likely to reflect both others' objective outcomes and their perceived intentions. The ventromedial prefrontal cortex (VMPFC) is one good candidate among neural structures that might represent social preferences. The medial PFC is important for a wide range of social cognitive tasks and social behaviors, and different regions seem to encode different components of social cognitive processing (). In particular, VMPFC activation correlates both with preferences for tangible personal outcomes (like money or food) and for social outcomes (like viewing attractive others or discovering that another person likes you) across a wide range of incentives and tasks (). The VMPFC also plays a critical role in social cognition and empathy more broadly (), which suggests that it may be engaged when people consider others' outcomes as well as their own ().

These theories generally assume that others' intentions are judged by observing past actions, such as how the seller has treated other buyers or how the employer has negotiated before. Judgments based on others' actions, however, can be biased by a range of individual and situational factors, such as the observer's personality, the stereotypes he or she holds, or what other information is provided (). If participants in similar economic games, for example, are given different intentions for the other players (that they are compelled by the experimenter, or by chance), then the same selfish or generous actions are judged less harshly or kindly ().

People often have to evaluate others' decisions, for instance, to decide whether a car seller's offered price is fair, or to arbitrate between an employer and employee in a wage conflict. In these evaluations, people generally care about outcomes, such as how much money is at stake or how much each party earns, but also about intentions, such as whether the seller is honest or the employer is negotiating fairly. Participants in economic games, for example, will sacrifice their own monetary payoffs to punish selfish players or reward generous players (). These evaluations are commonly analyzed with reciprocity-based theories of social decision-making (). Reciprocity-based theories propose formal models of preferences about others' outcomes, or “social preferences,” in which people prefer rewards for others with helpful intentions and punishments for others with harmful intentions.

Averaged across both conditions, inferential errors positively correlated with activation in right parietal cortex, such that higher-than-expected contributions increased activation in this region in both the Donation and Savings conditions ( Table 3 ). Inferential errors in both conditions correlated negatively with clusters in posterior cingulate bordering on the parietal cortex and in occipital cortex. These clusters also met only the exploratory cluster-size threshold.

Several regions in fact responded to inferential errors more in the Donation condition than in the Savings condition ( Table 3 and Figure 5 ; see also Table S3 for activations within condition). Inferential error activation was greater for the Donation condition in the right parahippocampal gyrus, left DLPFC, right temporoparietal junction, and cuneus. Inferential error activation was greater for the Savings condition only in left middle frontal gyrus. These clusters met the exploratory cluster-size threshold, but none was large enough to meet the whole-brain corrected threshold.

Regions where activation for inferential errors averaged across all players was greater for the Donation than the Savings condition. R indicates right. Color bar indicates t-statistic. Activations thresholded voxelwise at p < 0.001 with a ten-voxel extent minimum for display.

PFC = prefrontal cortex. Activations in table were thresholded voxelwise at p < 0.001 and with a cluster size greater than or equal to ten voxels (whole-brain corrected cluster-size threshold = 65 voxels). T-statistics were converted to Z-scores for reporting. Coordinates are reported in MNI/ICBM152 coordinates, as in SPM5. Resampled voxel size was 2 × 2 × 2 mm. See also Table S3 online for activation within conditions.

To examine whether neural responses to learning about players' contributions differed between conditions, we examined activation correlated with inferential errors, which were estimated by a reinforcement learning model that accurately predicted participants' actual inferences (see Supplemental Experimental Procedures for model details). The model estimated errors in a participant's inferred contribution for every player on every trial (positive for higher-than-expected contributions and negative for lower-than-expected contributions in both conditions). Imaging regressors then correlated these inferential errors with trial-by-trial activation when feedback was displayed. Within-participant contrast images that averaged across error regressors for all players were constructed; as before, these contrast images were compared in an independent-sample t test between Donation and Savings conditions. Greater contrast values for the Donation than the Savings condition would indicate (on average) more activation for higher-than-expected contributions and less activation for lower-than-expected contributions.

Since players' contributions influenced liking in the Donation but not Savings condition, participants must have updated their beliefs about participants differently between conditions in response to observing those contributions. The difference between conditions in how players updated their beliefs might be reflected by differential neural activation to observing the contributions on the trial-by-trial level. Brain areas that were more engaged for learning about contributions in the Donation than in the Savings condition might be involved not just in learning numerical amounts, but specifically in learning or updating beliefs about players' likability or their intentions to help and harm.

Only one area was more active for making High versus Low inferences in both conditions, a cluster in right rostromedial PFC ( Table 2 Figure 4 ). Several areas, however, were more active for Low versus High inferences in both conditions. These included anterior cingulate (ACC) overlapping dorsal MPFC (x / y / z = −2 / 18 / 44 mm, peak Z = 4.04, extent = 124 voxels, p < 0.001 corrected), right dorsolateral prefrontal cortex (DLPFC), anterior insula, and occipital cortex. Several areas of medial and lateral frontal cortex, then, encoded the difference between High and Low inferences identically across conditions, even though those inferences corresponded to opposite monetary outcomes in different conditions.

(B) Activation for Low versus High inferences in both conditions. R indicates right. Color bar indicates t-statistic for both panels. Activations thresholded voxelwise at p < 0.001 with a ten-voxel extent minimum for display.

We also examined the main effects of inference type (High or Low) across conditions. High inferences corresponded to opposite monetary outcomes between conditions (high donations or high savings), as did Low, but both kinds of inferences also shared several features; for example, High inferences always corresponded to larger numbers, and were always more consistent with the situational norms. To test the main effects, within-participant High versus Low contrast images for both conditions were averaged in a one-sample t test.

One important experimental control involved subjective certainty about inferences, which might also modulate prefrontal activation (). A reinforcement learning model was fit to each participant's behavior to estimate inferential certainty on each trial. After including regressors for certainty and estimated contribution sum, a smaller cluster of VMPFC was still activated for the interaction between inference and condition (see Table S2 ), suggesting that VMPFC activation was not due to differences in subjective certainty between conditions.

As predicted, VMPFC activation distinguished between High and Low inferences in the Donation but not the Savings condition ( Figure 3 ). The comparison revealed a cluster in VMPFC (x / y / z = 0 / 42 / −8 mm, peak Z = 3.75, extent = 58 voxels, p = 0.046 corrected), as well as several other regions including rostromedial prefrontal cortex (RMPFC), right middle temporal gyrus, and medial precuneus. The reverse interaction activated only one cluster in medial parietal cortex ( Table 2 ). VMPFC activation time courses suggested that the interaction was driven by increased activation for High inferences and decreased activation for Low inferences in the Donation condition, with little difference between High and Low inferences in the Savings condition. (See also Table S2 for activations within conditions.)

PFC = prefrontal cortex. Activations in table were thresholded voxelwise at p < 0.001 and with a cluster size greater than or equal to ten voxels (whole-brain corrected cluster-size threshold = 57 voxels). T-statistics were converted to Z-scores for reporting. Coordinates are reported in MNI/ICBM152 coordinates, as in SPM5. Resampled voxel size was 2 × 2 × 2 mm. See also Table S2 online for activation within conditions.

If VMPFC activation integrated others' objective monetary outcomes with their intentions to help or harm, the difference in activation between High and Low inferred contributions should be larger in the Donation condition (when contributions influenced player likability and perceptions of friendliness) than in the Savings condition (when they did not). To test the interaction of inferred contribution and condition, contrast images for making High versus Low inferences were calculated within participants. These contrast images were then compared between Donation and Savings condition participants in an independent-sample t test.

This pattern suggests that contributions in both Donation and Savings conditions had social meaning; participants in both conditions saw low contributions as indicative of dominance (i.e., placing individual goals before others'). However, in the Donation condition only, those contributions also influenced perceptions of friendliness, an interpersonal dimension identified with the intention to help or harm others ().

Instead, however, the effect of task condition was selective for perceived intentions to help or harm (see Figure S1 ). Specifically, judgments of dominance were unaffected by condition, such that low contributors were judged to be dominant in both conditions (F[1, 87.63] = 7.40, p = 0.01). The interaction of this effect with condition was not significant (F[1, 85.69] = 0.40, p = 0.53). By contrast, judgments of friendliness showed an identical pattern to liking; high contributors were judged to be friendly and low contributors were judged to be unfriendly in the Donation condition (main effect of estimated contribution: F[1, 86.58] = 82.38, p < 0.001), but this effect was significantly reduced in the Savings condition (interaction: F[1, 84.47] = 21.00, p < 0.001). There were no main effects of condition for either trait (dominance: F[1, 78.44] = 0.10, p = 0.75, friendliness: F[1, 79.44] = 1.58, p = 0.21).

To examine how interpersonal perceptions might be connected to liking, we also asked participants to judge players' interpersonal traits before and after the task, specifically, their dominance and their friendliness. One interpretation of the task condition's effect on liking might be that participants in the Savings condition saw players' contributions as purely individual decisions, unconnected to a social group. Differences in VMPFC activation between conditions might then be due to differences in “how social” the situation was perceived to be (). If the Savings condition changed whether players' contributions were perceived to have social meaning at all, then this condition should also decrease whether contributions affected any interpersonal traits.

Participants in the behavioral study performed the same task as FMRI participants, again in either the Donation or Savings condition. Accuracy and reaction time were similar to the FMRI study (see Table S1 ), and participants were again highly accurate in their explicit learning in both conditions (actual contribution effect on estimated contribution: F[1, 504] = 711.62, p < 0.001; interaction with condition: F[1, 504] = 0.29, p = 0.59). As well, participants' own hypothetical contributions were again higher in the Donation (M = $5.83, SEM = 0.33) than in the Savings condition (M = $2.81, SEM = 0.28; t[82] = 6.90, p < 0.001). The effect of players' estimated contribution on liking for players was also replicated. Participants liked high contributors and disliked low contributors in the Donation condition (main effect of estimated contribution: F[1, 86.68] = 76.82, p < 0.001), but this effect was significantly reduced in the Savings condition (interaction: F[1, 84.98] = 39.76, p < 0.001). There was again no main effect of condition on liking (F[1, 81.58] = 0.68, p = 0.41).

Both hypotheses were supported ( Figure 2 ). In the Donation condition, high contributors were liked and low contributors were disliked (F[1, 37.05] = 34.07, p < 0.001). This effect was symmetrical for high and low contributors, such that average liking across players did not differ from zero (F[1, 37.75] = 1.27, p = 0.27). The effect was qualified by a significant interaction with condition (F[1, 36.60] = 10.82, p = 0.002), reflecting a reduced effect of estimated contribution on liking in the Savings condition. There was no main effect of condition (F[1, 37.93] = 2.53, p = 0.12), indicating that participants did not differ between conditions in their average liking across players.

Points represent liking change from before to after the task for each player, plotted against the estimated average contribution for that player. Participants in the Savings condition saw savings amounts ($10 – contributions); contributions are displayed here for clarity. Error bars are standard errors across participants. See also Figure S1 online for changes in interpersonal ratings.

Next, to test how observed contributions and the task descriptions influenced players' perceived intentions, changes in liking for players were predicted using an MLM with estimated contribution, condition, and their interaction as predictors (including initial liking and the quadratic and random effects of estimated contribution as covariates of no interest). We hypothesized that estimated contribution would increase liking in the Donation condition, but that this effect would be reduced in the Savings condition.

Participants were asked how much they themselves would have contributed if they had played (framed either as a question about donating or saving). Participants' own hypothetical contributions were significantly higher in the Donation condition (M = $5.85, SEM = 0.43) than in the Savings condition (M = $3.56, SEM = 0.53; t[36] = 3.40, p = 0.002), suggesting participants viewed contributions more favorably in the Donation condition.

Participants inferred High slightly more often than Low, but this bias did not differ between conditions (mean High in Donation = 56.33%, SEM = 1.67%; mean High in Savings = 55.00%, SEM = 2.10%; t[36] = 0.50, p = 0.62). Reaction times were also faster for High than Low inferences by about 70 ms (High M = 1018.34, SEM = 35.08; Low M = 1084.60, SEM = 37.51; F[1, 36] = 10.00, p = 0.003), but this advantage did not differ by condition (F[1, 36] = 0.94, p = 0.34). High and Low inferences and reaction times were thus comparable across conditions.

To assess explicit learning, players' actual average contributions were used to predict participants' posttask estimates, using a mixed linear model (MLM) with actual contribution, condition, and their interaction as predictors. Perfect learning would correspond to an average estimate (i.e., model intercept) of $5 and an actual contribution slope of $1. Participants made highly accurate estimates of average contributions. Actual contribution significantly predicted estimated contribution (F[1, 228] = 458.79, p < 0.001), and the model intercept of $4.90 did not differ significantly from $5.00 (95% confidence interval [CI]: $4.68–$5.09). The actual contribution slope was $0.88, significantly less than $1 (95% CI: $0.80–$0.96), indicating that participants tended to overestimate low contributions and underestimate high contributions. Condition had no main effect or interaction (main effect: F[1, 228] = 0.03, p = 0.85; interaction: F[1, 228] = 1.37, p = 0.24). Participants therefore made similarly accurate estimates of numerical contributions in both conditions.

Reaction time (averaged over blocks of 15 trials) declined over time, but also did not differ between conditions ( Table 1 ). Polynomial contrasts indicated both linear (F[1, 36] = 8.65, p = 0.006) and quadratic (F[1, 36] = 5.47, p = 0.025) effects, such that the speeding of reaction time declined over blocks. There was no main effect of condition (F[1, 36] = 2.17, p = 0.15) or interaction between condition and time (F[3, 108] = 1.69, p = 0.17), indicating that participants spent similar amounts of time making inferences between conditions.

Performance was measured as the percentage of correct inferences, averaged over blocks of 15 trials within conditions. Correct inferences increased over time, and did not differ between conditions ( Table 1 ). Performance was above chance for all blocks; the worst performance was 59.63% correct in the first block of the Savings condition (t[17] = 2.57, p = 0.02). Polynomial contrasts indicated only a significant linear effect (F[1, 36] = 10.28, p = 0.003). There was no main effect of condition (F[1, 36] = 0.004, p = 0.95) or interaction between condition and time (F[3, 108] = 0.09, p = 0.97). Performance reached an identical plateau in both conditions of about two-thirds correct. For comparison, a participant with perfect knowledge of all players' strategies could have been correct on 76% of trials, due to the probabilistic nature of the task.

n = 38 (20 in Donation condition, 18 in Savings condition). Blocks are 15 trials long. Standard errors of the mean (SEM) are calculated within block and condition. See also Table S1 online.

For consistency, results are described in terms of contributions. Contributions match the numbers that participants in the Donation condition saw but are reversed from what participants in the Savings condition saw (for example, an $8 contribution was seen as a $2 savings). When describing inferences, however, we retain the original framing, to match the words that all participants saw. Results associated with High (versus Low) inferences in the Donation condition are thus associated with contributions of $20 or more, while results associated with High (versus Low) inferences in the Savings condition are associated with savings of $20 or more.

Discussion

When evaluating others' decisions, people consider both their outcomes as well as their intentions. To determine how others' outcomes and intentions were integrated neurally, the current study examined individuals in two conditions of a novel social observation task in separate FMRI and behavioral experiments. All participants made inferences about the outcomes of players in a public goods game in which the participant had no personal stake, and during which the players used strategies ranging from generous to selfish. Participants in the Donation condition saw the game in terms of donations that helped or harmed other people, while participants in the Savings condition saw the same game in terms of savings that individuals maximized in a series of risky market investments. The Donation condition was designed to evoke emotional judgments of players' intentions to help or harm others, while the Savings condition was designed to disengage those judgments.

In the VMPFC, a key structure for evaluating personal outcomes, activation for others' outcomes was significantly affected by judgments of their intentions. In the Donation condition, VMPFC activation increased for high contribution inferences, which helped the group, and decreased for low contribution inferences, which harmed the group. In the Savings condition, however, VMPFC activation did not significantly vary when participants inferred high versus low contributions.

These findings are consistent with the idea that VMPFC activation reflects an integrated evaluation that can guide decisions. In this study, though, these evaluations were solely about others' outcomes. If VMPFC activation only represented personal outcomes, this region should not have responded in either condition, since participants had no monetary stake in the game and knew they would not interact with the players. If, by contrast, the VMPFC only simulated others' objective outcomes during observation, its activation should not have distinguished between conditions, as the observed monetary outcomes in the Savings and Donation conditions were identical. Neither of these accounts matches the current findings.

Instead, a social preference account suggests that participants preferred high contributions to low contributions in the Donation condition, but did not distinguish between them in the Savings condition. Why would preferences for the same outcomes differ between conditions? The clearest possibility is that different descriptions of the public goods game evoked different emotional judgments of players' intentions. Reciprocity-based theories of social preferences suggest that others' intentions to help or harm others play a key role in determining a personal response to their outcomes. Typically, those intentions are judged from behavior. For instance, a player who pursues a “nice” strategy (i.e., donates to the group) is seen as more likable than one who pursues a “nasty” strategy (i.e., withholds donations), and hence rewards for the nice player are preferred.

This judgment process, however, is not fixed; in this study, judgments differed across conditions. High and low contributions only suggested the intention to help or harm others in the Donation condition, as confirmed by changes in liking and ratings of friendliness in the Donation but not in the Savings condition. One possibility is that the framing manipulation changed the basis for moral evaluation. Low contributors were always perceived to put the individual before the group (as confirmed by ratings of dominance in both conditions). In the Donation condition, when pro-group norms were promoted, these norm violations were seen as antisocial and unlikable. In the Savings condition, when pro-individual norms were promoted, low contributions were no longer a violation or an offense. Antisocial actions that seem justified do not generate the same level of outrage as the same actions evaluated as spiteful or competitive.

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Banaji M. Dissociable medial prefrontal contributions to judgments of similar and dissimilar others. Other regions of the medial PFC encoded different representations of players' actions that might correspond with different kinds of judgments. Rostromedial PFC was more active for inferring High in both conditions (at the exploratory cluster threshold), even though High inferences corresponded to different monetary outcomes (contributing or saving) across conditions. High inferences, however, were always more consistent with situational norms, as well as the participants' own hypothetical donations. This region has been linked to “mentalizing,” the process of considering others' mental states and intentions (). In particular, this region is more active when considering intentions with clearer explanations, or when judging others who are more similar to the self (). Activation in this region may thus reflect a situational norm for High inferences across conditions; this norm would provide a clearer reason for High donations/savings than for Low and may have led participants to feel more similar to those following the norm.

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Huettel S. Risky business: the neuroeconomics of decision making under uncertainty. By contrast, Low inferences in both conditions activated a network including ACC, DLPFC, and insula. The ACC and DLPFC especially are involved in response conflicts like overriding a prepotent response, as in the Stroop or oddball tasks (), while the insula has been linked to detecting and processing uncertainty (). Activation of this network suggests that there was a prepotent response toward High inferences, an idea supported by the choice bias and slower reaction times in Low inferences. This interpretation is again consistent with a situational norm across conditions toward High and away from Low inferences, regardless of the monetary outcomes. Low outcomes may have seemed less likely or desirable due to the condition's described norms, and hence inferring Low may have required overriding the “default” prediction about players' behavior.

Taken together, these results suggest that in more dorsal MPFC (RMPFC and ACC), neural representations of players' intentions were relatively less sensitive to their objective monetary outcomes, and more sensitive to whether their behavior was consistent or inconsistent with the situational norms. Inferring behavior consistent with the condition's norm activated mentalizing regions, while inferring inconsistent behavior activated regions linked to response conflict, even when that norm objectively reversed between donating and saving.

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Kerekes A.R.Z. A distributed-memory model of averaging phenoman in person impression-formation. Inferential errors were associated with greater activation (positive and negative) in the right TPJ for participants in the Donation condition. Right TPJ activation has been associated with judging others' intentions in a variety of other social cognitive tasks (). Activation in this region suggests that in the Donation condition, participants saw contributions as more informative about players' intentions to help or harm, consistent with the greater effect of contributions on liking in this condition. Inferential errors in the Donation condition were also associated with greater activation in the right parahippocampal gyrus and left DLPFC, which have been linked to explicit memory encoding (). Donation participants learned more about players' intentions from the same numerical feedback; that learning may have changed existing cognitive representations about the players, such as beliefs about their personality traits. This interpretation is consistent with social psychological models using reinforcement learning algorithms (), in which inferential errors play a similar role to reward prediction errors in studies of incentive learning, that is, improving existing beliefs about others' traits based on feedback.

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Dalgleish T. A key role for similarity in vicarious reward. These findings extend a growing line of research on how social contextual factors can modulate neural representations of others' outcomes. Others' outcomes, such as donations to charity, can activate reward-sensitive regions like the ventral striatum, even when observers have no personal stake (). These activations, though, can depend on emotional judgments of those others. Individuals watching others receive electric shocks, for example, had reduced activation in pain-sensitive regions such as the insula and ACC if those others had played unfairly in a prior economic game (). In another study, when individuals read about others' misfortunes, they had greater activation in the ventral striatum when they envied those people than when they did not (). Contextual modulation can also account for reactions to others' decisions and rewards. In one study, in which participants played economic games with fictional partners given likable, neutral, or unlikable back stories, the ventral caudate was activated only in response to cooperative decisions if the partner was unlikable or neutral, but was activated for both cooperation and noncooperation if the partner was likable (). In another study, individuals watching another player win in a gambling game had greater ventral striatal activation when that player had previously expressed likable (compared with unlikable) personal traits in a taped interview. Further, VMPFC activation in response to those wins was modulated by subjective similarity to the player (but not by liking of him or her;).

The current findings suggest that observing others' outcomes can activate neural structures that are also recruited by personal outcomes, such as the VMPFC, and highlight again that this activity depends upon the social context. Earlier studies, however, manipulated this context by manipulating the others' actual behavior (e.g., changing whether they had done likable things or played fairly). This study demonstrates that VMPFC activation is affected by others' intentions independent of their actions. Generous and selfish players made the same contributions in both conditions. Participants only judged their intentions as helpful or harmful, however, when contributing was described in terms of its consequences for the group, and only then did VMPFC activation vary.

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Sigmund K. Evolution of indirect reciprocity by image scoring. Byrne, 1971 Byrne D. The Attraction Paradigm. The effect of the task descriptions on liking has implications for reciprocity-based models of social preference. These models typically assume individuals automatically judge the “niceness” or “nastiness” of other players, echoing evolutionary accounts of altruism that rely on knowing others' past reputations (). The current findings support these accounts, since merely observing others' contributions in a public goods game can drive formation of strong preferences. Social liking and disliking can persist well beyond observation of a single act and can influence unrelated decisions (), and thus the current results imply that deciding to contribute can have a long-term impact on one's reputation. At the same time, the results emphasize that the judgment of others' niceness or nastiness is not fixed by their behavior, but depends on how it is described. The offered price for a car might seem high when the seller's high profits are emphasized, but the seller might highlight the need to pay his or her staff; similarly, an arbitrator might view a wage offer differently when it is described as an “institutional savings measure” instead of a “pay cut.” In the current study, a high contributor might choose to be described as a “high donator,” while a low contributor might choose the “high saver” description. These descriptions influence both observers' judgments and their neural responses to observing contributions, or failures to contribute.

In summary, when individuals observed others in an economic game described in terms of donations to the group, they liked high contributors and disliked low contributors even when they had no personal stake in the game. In this Donation condition, VMPFC activation increased when inferring generous play and decreased when inferring selfish play. When participants observed the same game in a Savings condition that described play in terms of individual savings, neither VMPFC activation nor liking changed during inference. Regardless of the objective outcomes in each condition, rostromedial PFC activation increased for inferring behavior consistent with the condition's norm, while ACC, DLPFC, and insula activation increased for inconsistent behavior. In addition, inferential errors for observed contributions recruited brain regions linked to social cognition and memory (including the TPJ, DLPFC, and parahippocampal gyrus) in the Donation more than the Savings condition. These findings are consistent with the idea that in the Donation condition, individuals perceived contributions as more informative of others' intentions to help or harm, and that those intentions were integrated with the value of others' outcomes in the VMPFC. This region may thus play a key role in representing preferences about others' outcomes, above and beyond one's own. Those preferences, though, depend crucially on the perceived intentions behind others' actions.