Tipping pro-environmental norm diffusion at scale: opportunities and limitations

Rapid and comprehensive social change is required to mitigate pressing environmental issues such as climate change. Social tipping interventions have been proposed as a policy tool for creating this kind of change. Social tipping means that a small minority committed to a target behaviour can create a self-reinforcing dynamic, which establishes the target behaviour as a social norm. The possibility of achieving the large-scale diffusion of pro-environmental norms and related behaviours with an intervention delimited in size and time is tempting. Yet, the canonical model of tipping, the coordination game, may evoke overly optimistic expectations regarding the potential of tipping, due to the underlying assumption of homogenous preferences. Relaxing this assumption, we devise a threshold model of tipping pro-environmental norm diffusion. The model suggests that depending on the distribution of social preferences in a population, and the individual cost of adopting a given pro-environmental behaviour, the same intervention can activate tipping, have little effect, or produce a backlash. Favourable to tip pro-environmental norms are widespread advantageous inequity aversion and low adoption costs. Adverse are widespread self-regarding preferences or disadvantageous inequity aversion, and high costs. We discuss the policy implications of these findings and suggest suitable intervention strategies for different contexts.

Social disappointment and partner presence affect long-tailed macaque refusal behaviour in an "inequity aversion" experiment

Inequity aversion plays a central role in human cooperation. Some animals similarly show frustration and become demotivated when rewarded more poorly than a conspecific, which has been taken as evidence of inequity aversion. An alternative explanation - social disappointment - shifts the cause of frustration from the unequal reward to the human experimenter who could – but elects not to – treat subject and partner equally. This study investigates whether social disappointment could explain frustration patterns in long-tailed macaques, Macaca fascicularis. We tested twelve monkeys in a novel inequity aversion paradigm. Subjects had to pull a lever and were rewarded with low-value food; in half of the trials a partner worked alongside the subjects receiving high-value food. Rewards were distributed either by a human or a machine. In line with the social disappointment hypothesis monkeys rewarded by the human refused food more often than monkeys rewarded by the machine. Our study extends previous findings in chimpanzees and suggests that both social disappointment and food competition drive refusal patterns.

A comparative test of inequity aversion in domestic dogs (Canis familiaris) and dingoes (Canis dingo)

Despite much recent empirical work on inequity aversion in nonhuman species, many questions remain about its distribution across taxa and the factors that shape its evolution and expression. Past work suggests that domestic dogs (Canis familiaris) and wolves (Canis lupus) are averse to inequitable resource distributions in contexts that call upon some degree of training such as ‘give paw’ and ‘buzzer press’ tasks. However, it is unclear whether inequity aversion appears in other canid species and in other experimental contexts. Using a novel inequity aversion task that does not require specific training, this study helps address these gaps by investigating inequity aversion in domestic dogs and a closely related but non-domesticated canid, the dingo (Canis dingo). Subjects were presented with equal and unequal reward distributions and given the opportunity to approach or refuse to approach allocations. Measures of interest were (1) subjects’ refusal to approach when getting no food; (2) approach latency; and (3) social referencing. None of these measures differed systematically across the inequity condition and control conditions in either dogs or dingoes. These findings add to the growing literature on inequity aversion in canids, providing data from a new species and a new experimental context. Additionally, they raise questions about the experimental features that must be in place for inequity aversion to appear in canids.

Neural representations of stereotype content predict social decisions

Perceptions of others' traits based on social group membership (stereotypes) are known to affect social behavior, but little is known about the neural mechanisms mediating these effects. Here, using fMRI and representational similarity analysis (RSA), we investigated neural representations of others' traits and their contributions to social decision making. Behaviorally, perceptions of others' traits, captured by a two-dimensional framework, biased participants' monetary allocation choices in a context-dependent manner: recipients' perceived warmth increased advantageous inequity aversion and competence increased disadvantageous inequity aversion. Neurally, RSA revealed that stereotypes about others' traits were represented in activity patterns in the temporoparietal junction and superior temporal sulcus, two regions associated with mentalizing, and in the lateral orbitofrontal cortex (OFC), known to represent latent environmental features during goal-directed outcome inference. Critically, only the latter predicted individual choices, suggesting that the effect of stereotypes on behavior is mediated by inference-based, goal-directed decision-making processes in the OFC.

Explaining Individual Differences in Advantageous Inequity Aversion by Social-Affective Trait Dimensions and Family Environment

Humans are averse to both having less (i.e., disadvantageous inequity aversion [IA]) and having more than others (i.e., advantageous IA). However, the social-affective traits that drive individual differences in IA are not well understood. Here, by combining a modified dictator game and a computational model, we found in a sample of incarcerated adolescents ( N = 67) that callous-unemotional traits were specifically associated with low advantageous but not disadvantageous IA. We replicated and extended the finding in a large-scale university student sample ( N = 2,250) by adopting a dimensional approach to social-affective trait measures. We showed that advantageous IA was strongly and negatively associated with a trait dimension characterized by callousness and lack of social emotions (e.g., guilt and compassion). A supportive family environment negatively correlated with this trait dimension and positively with advantageous IA. These results identify a core set of social-affective dimensions specifically associated with advantageous IA.

Reciprocity With Unequal Payoffs: Cooperative and Uncooperative Interactions Affect Disadvantageous Inequity Aversion

Cooperation among unrelated individuals can evolve through reciprocity. Reciprocal cooperation is the process in which lasting social interactions provide the opportunity to learn about others' behavior, and to further predict the outcome of future encounters. Lasting social interactions may also decrease aversion to unequal distribution of gains – when individuals accept inequity payoffs knowing about the possibility of future encounters. Thus, reciprocal cooperation and aversion to inequity can be complementary phenomena. The present study investigated the effects of cooperative and uncooperative interactions on participants' aversion to disadvantageous inequity. Participants played an experimental task in the presence of a confederate who acted as a second participant. In reality, the participant interacted with a computer programed to make cooperative and uncooperative choices. After interacting with a cooperative or uncooperative computer, participants chose between blue cards to produce larger gains to the computer and smaller for him/her or green cards to produce equal and smaller gains for both. Results confirmed our first hypothesis that uncooperative interactions would produce aversion to disadvantageous inequity. Lastly, half of the participants were informed that points received during the experiment could be later exchanged for money, and half were not. Results indicated that information about monetary outcomes did not affect aversion to inequity, contradicting our second hypothesis. We discuss these results in the light of theories of reciprocal cooperation, inequity aversion, and conformity.

A Computational Model of Non-optimal Suspiciousness in the Minnesota Trust Game

This study modeled spite sensitivity (the worry that others are willing to incur a loss to hurt you), which is thought to undergird suspiciousness and persecutory ideation. Two samples performed a parametric, non-iterative trust game known as the Minnesota Trust Game (MTG). The MTG is designed to distinguish suspicious decision-making from otherwise rational mistrust by incentivizing the player to trust in certain situations. Individuals who do not trust even under these circumstances are particularly suspicious of their potential partner’s intentions. In Sample 1, 243 undergraduates who completed the MTG showed less trust as the amount of money they could lose increased. However, for choices where partners had a financial disincentive to betray the player, variation in the willingness to trust the partner was associated with suspicious beliefs. To further examine spite sensitivity, we modified the Fehr-Schmidt (1999) inequity aversion model, which compares unequal outcomes in social decision-making tasks, to include the possibility for spite sensitivity. In this case, an anticipated partner’s dislike of advantageous inequity (i.e., guilt) parameter could take on negative values, with negative guilt indicating spite. We hypothesized that the anticipated guilt parameter would be strongly related to suspicious beliefs. Our modification of the Fehr-Schmidt model improved estimation of MTG behavior. We isolated the estimation of partner’s spite-guilt, which was highly correlated with choices most associated with persecutory ideation. We replicated our findings in a second sample, where the estimated spite-guilt parameter correlated with self-reported suspiciousness. The “Suspiciousness” condition, unique to the MTG, can be modeled to isolate spite sensitivity, suggesting that spite sensitivity is separate from inequity aversion or risk aversion, and may provide a means to quantify persecution. The MTG offers promise for future studies to quantify persecutory beliefs in clinical populations.

Explaining individual differences in advantageous inequity aversion by social-affective trait dimensions and family environment

Humans are averse to both having less (i.e., disadvantageous inequity aversion) and having more than others (i.e., advantageous inequity aversion). However, the social-affective traits that drive individual differences in inequity aversion (IA) are not well understood. Here, by combining a modified Dictator Game and a computational model, we found in a sample of incarcerated adolescents (N = 67) that callous-unemotional traits were specifically associated with low advantageous but not disadvantageous IA. We replicated and extended the finding in a large- scale university student sample (N = 2,250) by adopting a dimensional approach to social- affective trait measures. We showed that advantageous IA was strongly and negatively associated with a trait dimension characterized by callousness and lack of social emotions (e.g., guilt and compassion). A supportive family environment negatively correlated with this trait dimension and positively with advantageous IA. These results identify a core set of social- affective dimensions specifically associated with advantageous IA.