Beliefs and predictions about harm preferences

We first investigated participants’ ability to develop accurate beliefs about the agents’ objective harm preferences and predict their decisions. On average, participants predicted accurately 72% of the good agent’s choices and 77% of the bad agent’s choices. There was no relationship between ETV score and prediction accuracy for either agent (Spearman’s ρ, good: ρ = −0.065, p = 0.483; bad: ρ = 0.043, p = 0.639). This suggests that participants with higher exposure to violence were equally motivated to learn the harm preferences of the agents, relative to those with lower exposure to violence.

Next, we examined how rapidly participants updated their beliefs about the agents’ preferences in response to feedback. To this end, we fit a hierarchical Bayesian model for learning stable preferences under conditions of uncertainty to participants’ predictions. The model defines how beliefs about an agent’s harm preference evolve over time as a function of a participant-specific parameter ω, capturing inter-individual differences in the rate of belief updating (see Methods and Fig. 1b)30. Formal model comparison indicated that the hierarchical Bayesian model outperformed two alternative Rescorla Wagner models in our sample of participants (see Methods and Supplementary Note 1). Replicating previous research18, beliefs about the bad agent’s preferences were more rapidly updated in response to feedback, as indicated by a higher ω, than beliefs about the good agent’s preferences (signed rank test, Z = −2.328, p = 0.020; Fig. 2a). ETV score was not significantly related to ω for either agent (Spearman’s ρ, good: ρ = 0.025, p = 0.785; bad: ρ = −0.014, p = 0.879), nor was it related to the difference in ω between good and bad agents (Δω: ρ = 0.008, p = 0.929; Fig. 2b). Together, these results suggest that objective harm learning was largely intact in this sample and did not covary with exposure to violence.

Fig. 2 Objective harm learning does not covary with exposure to violence. a Beliefs about the bad agent’s harm preferences were more volatile than beliefs about the good agent’s harm preferences. b Between-agent asymmetries in belief updating (Δω = bad agent belief volatility − good agent belief volatility) were not related to participant’s ETV score, suggesting that exposure to violence does not significantly impact the underlying processes of objective harm learning. Error bars represent standard error of the mean. Error bands represent 95% confidence intervals. Source data are provided as a Source Data file Full size image

Subjective impressions of the agent’s moral character

Despite the fact that ETV score did not impact learning the objective features of agents’ preferences, we observed a strong effect of ETV score on participants’ subjective global impressions of the agent’s moral character. A robust linear regression was used to predict subjective moral impression ratings as a function of agent (good vs. bad), ETV score, and their interaction. We report means and standard error of the mean (sem) as mean ± sem. We included an additional regressor to control for trial number, and found no effects on impression ratings (β = 0.003 ± 0.003, t = 0.955, p = 0.340). Replicating previous research, in general, participants formed more favorable impressions of the good agent’s moral character than the bad agent’s moral character (β = −1.300 ± 0.075, t = −17.284, p < 0.001). Higher ETV scores predicted more negative impressions of the good and bad agents’ moral character (β = −0.018 ± 0.006, t = −2.902, p = 0.004). There was a significant interaction between ETV score and type of agent (β = 0.037 ± 0.009, t = 4.222, p < 0.001), indicating that for participants with higher ETV scores, there was less differentiation in their impressions of the good and bad agents’ moral character (Fig. 3a).

Fig. 3 Model estimates showing diminishing effects of agent with increasing exposure to violence. Participants with higher ETV scores showed less differentiation in their subjective impressions of good (blue line) vs. bad (red line) agent’s moral character (a) and reported smaller discrepancies in the uncertainty of their impressions of good and bad agents (b). Higher ETV scores also resulted in smaller discrepancies in the amounts that participants entrusted with good vs. bad agents in a one-shot trust game (c). Y-axis in figures a and b denote standardized values (z-scored). Error bands represent 95% confidence intervals. Source data are provided as a Source Data file Full size image

To further investigate the interaction between type of agent and exposure to violence on subjective impression ratings, we ran separate regressions on ratings for the good and bad agent. Specifically, we asked whether diminishing effects of agent with higher ETV scores were driven by the good agent, the bad agent, or both. These analyses revealed that the effects were not specifically driven by either agent alone. Higher ETV scores predicted more favorable impressions of the bad agent (β = 0.019 ± 0.007, p = 0.004) and less favorable impressions of the good agent (β = −0.019 ± 0.006, p = 0.001; see Fig. 3a).

Of note, participants with higher ETV scores were no more likely to predict worse harm intentions of the agents in the task before they observed any of their choices (Spearman’s ρ, ρ = −0.082, p = 0.361) and were no less trusting of others in general (as indicated by scores on the General Trust scale31; ρ = −0.040, p = 0.665). These findings suggest that exposure to violence affects how participants in this sample form subjective impressions about other’s moral character through observing their choices, rather than affecting prior beliefs about others.

Certainty of subjective impressions

Past work in non-incarcerated samples indicates that adults hold more certain positive impressions of others and more uncertain negative impressions, which is hypothesized to serve the adaptive social function of enabling people to more easily update negative impressions that turn out to be inaccurate18,32. Consistent with previous research, uncertainty decreased over time as participants were exposed to more information about the agents’ harm preferences (Robust regression, β = −0.018 ± 0.003, t = −5.969, p < 0.001). Furthermore, participants expressed greater uncertainty in their impressions of the bad agent, relative to the good agent (β = 0.513 ± 0.078, t = 6.605, p < 0.001).

To investigate whether exposure to violence affected participants’ uncertainty in their impressions of the agents’ moral character, we performed a robust linear regression to investigate the effects of agent, ETV score, and their interaction on participants’ ratings of uncertainty about their impressions of the agents. Participants with higher ETV scores were more uncertain in their impressions overall (β = 0.019 ± 0.006, t = 2.982, p = 0.003), and this interacted with the effect of agent (β = −0.045 ± 0.009, t = −4.973, p < 0.001; Fig. 3b). Consistent with our findings on subjective impressions, the interaction indicated that participants with higher ETV scores expressed smaller differences in their uncertainty ratings between good and bad agents, such that they became more uncertain that the good agent was good, and less uncertain that the bad agent was bad. Notably, smaller differences in impression ratings between good and bad agents predicted less discrepant uncertainty ratings (Spearman’s ρ, ρ = 0.336, p < 0.001). Finally, mirroring the subjective impression results, these effects were not specifically driven by either agent alone. Higher ETV scores predicted less uncertain impressions of the bad agent (β = −0.025 ± 0.007, t = −3.795, p < 0.001) and more uncertain impressions of the good agent (β = 0.019 ± 0.006, t = 3.126, p = 0.002; see Fig. 3b). Results from our robust linear regressions did not change after controlling for age and education (see Supplementary Tables 4, 5).

Trust behavior

Although exposure to violence impaired participants’ ability to form distinct subjective impressions of agents with different harm preferences, it is unclear whether this has consequences for social behavior. To address this question, we asked participants to engage in a one-shot trust game with each of the agents, after predicting all the agents’ choices in the harm learning task (see Methods). Previous work has shown that non-incarcerated adults adjust their behavior in the trust game according to the harm preferences of the agent with whom they are interacting (i.e., people entrust significantly less money with those who treat others poorly than those who treat others well18,33).

To investigate whether adaptive trust behavior was diminished in participants with higher ETV scores, we entered the amount participants entrusted in a repeated measures general linear model with agent (good vs. bad) as the within-subject factor and ETV score as a continuous covariate. Consistent with previous research, participants entrusted more points with the good agent than the bad agent (F(1,119) = 6.202, p = 0.014, η2 = 0.056). The effect of agent was significantly moderated by ETV score (F(13,119) = 2.142, p = 0.017, η2 = 0.210; Fig. 3c). The interaction indicated that higher ETV scores predicted smaller discrepancies in the amount participants entrusted with the good vs. the bad agent. Specifically, those with higher ETV scores entrusted significantly less with the good agent (Spearman’s ρ, ρ = −0.220, p = 0.016), and consequently ended up earning fewer points overall (ρ = −0.325, p < 0.001). ETV scores did not significantly affect the amount that participants entrusted with the bad agent (ρ = 0.119, p = 0.198). Thus, exposure to violence was associated with maladaptive trusting behavior, specifically when interacting with those who are less willing to harm others, and this had a negative impact on their overall earnings.

Given the relationship between exposure to violence and differential trust behavior (Δentrust, calculated as amount entrusted with good agent − amount entrusted with bad agent), it is possible that participants’ final subjective impressions of the agents’ moral character (Δjudgment, calculated as final impression of the good agent – final impression of the bad agent) account for (i.e., mediate) that relationship. We found a significant indirect effect of Δjudgment on Δentrust, effect = −0.812, CI [−1.705, −0.054] (see Supplementary Note 2 for full mediation results and additional analysis), suggesting that impressions about other’s moral character account for differences in social behavior among participants with higher levels of exposure to violence.

Despite these results, some might question the validity of the trust game in the current sample given their incarceration status. Therefore, we examined whether the extent to which participants adjusted their trust behavior according to the agents’ harm preferences predicted social behavior in prison. Less discrepant behavior towards good and bad agents was associated with more behavioral violations in prison (Spearman’s ρ, ρ = −0.208, p = 0.023), and specifically with aggressive violations against persons (ρ = −0.217, p = 0.020). This suggests the ability to adjust trust behavior based on impressions of other’s moral character, as measured by our task, captures variance in real-world social behavior.

However, it’s possible that this relationship between less discrepant behavior towards good and bad agents and more behavioral violations in prison is largely explained by the relationship with ETV scores. Indeed, higher ETV scores predict more behavioral violations in prison (Spearman’s ρ, ρ = 0.450, p < 0.001). However, we predicted that this relationship would be mediated by the extent to which participants differentiated in their subjective impressions and trust behavior between the good and bad agent. Consequently, we applied a serial multiple mediation analysis using the PROCESS macros for SPSS34 (model 6) that allowed us to determine the causal link between mediators with a specified direction of causal flow. We investigated whether the relationship between exposure to violence and prison violations was mediated by trust behavior (Δentrust) as a function of impression sensitivity (Δjudgment). ETV score was only a marginally significant predictor of prison violations after impression sensitivity and trust behavior were accounted for (direct effect = 0.622 ± 0.340, p = 0.070). The indirect effects were tested using a bootstrap estimation approach with 5000 samples. These results indicated the indirect serial coefficient was significant (indirect effect = 0.099 ± 0.071, 95% CI = [0.002, 0.274]; see Supplementary Note 3 for full mediation results and Supplementary Fig. 1), suggesting that disruptions in the ability to form distinguishable impressions resulting from higher ETV scores, translates into maladaptive trust behavior, which in turn leads to a greater number of direct violations in prison.

Specificity of exposure to violence effects

Previous work has shown that exposure to violence is associated with antisocial behavior and psychopathic traits10,35,36,37. Here we also found that ETV score was associated with increased antisociality, as indicated by higher scores on the Hare Psychopathy Checklist-Revised38 (PCL-R) and increased symptoms of Antisocial Personality Disorder39 (APD) (Spearman’s ρ, PCL-R total score: ρ = 0.394, p < 0.001; APD symptoms: ρ = 0.261, p = 0.004). This leaves open the question of whether the effects of exposure to violence on subjective impressions observed here are a primary consequence of exposure to violence, or an indirect consequence of possessing characteristics that predispose exposure to violence, such as Psychopathy or Antisocial Personality Disorder. To assess whether ETV score had a direct, as opposed to indirect, effect on subjective impressions and uncertainty ratings, and social behavior, we entered each covariate (PCL-R total score and total number of APD symptoms) separately into our regressions with ETV score. Across all measures, we found that interactions between agent and ETV score remain significant even when we include the interaction between agent and each covariate (see Supplementary Tables 4–6 for all analyses including covariates). An alternative possibility is that the observed effects of exposure to violence on impressions reflect a general impact of traumatic experiences, rather than being specific to community violence. To investigate, we entered scores from the Childhood Trauma Questionnaire40 (CTQ) into our regression with ETV score. Again, we found that the interactions between agent and ETV score remain significant even after controlling for CTQ (see Supplementary Tables 4–6 for full analysis). Together, this suggests that being exposed to violence had a direct effect on subjective impressions of moral character and social behavior and that findings could not be entirely explained by antisocial psychopathology or childhood trauma.