The research, conducted by Marius C. Vollberg of the University of Zurich and University of Geneva and Jörg Gross of the University of Zurich, spans nine preregistered online experiments involving 8,769 adults, predominantly residents of the United States. The central finding is striking in its symmetry: both selfish and prosocial individuals distort the social consequences of their choices, but they do so in predictably different directions. Selfish people shrink the apparent harm of their actions, while prosocial people inflate the apparent benefit of theirs. Crucially, when these distorted interpretations are transmitted to others, only the selfish-serving version reliably spreads, nudging those who encounter it toward more selfish behaviour.

The experimental logic was elegantly simple. Participants, cast as ‘Deciders’, chose between two options with fully known personal payoffs: option A yielded 7 points for themselves, option B yielded 5. Each option also carried an ambiguous consequence for another anonymous participant, the ‘Receiver’. Option A gave the Receiver between 1 and 3 points, option B between 3 and 5. Because the Decider’s own payoff was certain while the Receiver’s was a range, the design captured a fundamental asymmetry in social life: personal outcomes are immediate and tangible, whereas social outcomes are shadowy and hard to verify. After choosing, participants estimated the Receiver’s actual outcome for both options, with real money riding on the accuracy of their guesses.

If participants treated each outcome within a range as equally likely, their estimates should cluster around the midpoint and should not depend on what they chose. That is not what happened. Selfish Deciders, those who took the higher payoff, reported the two options’ social consequences as more similar than prosocial Deciders did, effectively portraying their choice as socially harmless. Statistically, the difference was robust: prosocial Deciders’ estimates exceeded selfish Deciders’ by a coefficient of 0.24, with a 95 percent confidence interval of 0.14 to 0.34. Selfish Deciders exaggerated the Receiver’s outcome under the selfish option while downplaying it under the prosocial option, compressing the apparent moral gap between the two choices until their selfishness looked costless.

Prosocial Deciders distorted too, but differently. They exaggerated the social benefit of the option they chose, and, intriguingly, they also exaggerated the benefit of the selfish option they rejected. Rather than painting their sacrifice as heroic against a dark alternative, they construed a world in which even a modest social benefit justified forgoing personal gain, casting themselves as people who need little prompting to do good. In a neutral condition where the self-maximizing option also maximized the Receiver’s payoff, removing any conflict between self-interest and social interest, estimates drifted closer to the true midpoints, though some downplaying of the unchosen alternative persisted.

Sceptics might wonder whether these deviations reflect genuine beliefs about how the ambiguous outcomes were generated rather than motivated distortions. The team addressed this in a conceptual replication that made the outcome-generation process fully transparent: participants watched an animation showing numbers being sampled into an urn and one drawn at random, making clear that the expected value equalled the range midpoint and that their choice could not influence the process. Distortions persisted. The selfish pattern replicated in full, and the overall difference between Decider types remained strong, indicating that the effects cannot be dismissed as private theories about hidden sampling procedures.

Two further experiments probed the psychology behind the distortions. When participants reported their estimates before choosing, the distortions were already present, though attenuated, ruling out a purely post-hoc justification account. More decisive was a forced-choice design in which participants were randomly assigned to implement either the selfish or the prosocial option. If distortions served to justify specific actions, forcing a choice should have reshaped them accordingly. Instead, distortions tracked participants’ underlying social preferences, measured under free choice, better than the choice they had been forced to make; a Bayesian model comparison strongly favoured the preference-based account. Distortions, in other words, are not excuses manufactured after the fact but preference-consistent interpretations of social reality.

Yet the distortions also revealed a telling double standard. In a separate task, participants faced the very same ambiguous ranges, but this time the outcomes determined their own bonuses. Their earlier estimates about others’ outcomes did not predict how they treated equivalent ambiguity when their own money was at stake. People who had reported that a 3-to-5 range favoured the Receiver did not behave as if they believed it when choosing gambles for themselves. This suggests the distortions are not sincere beliefs about underlying distributions but selective interpretations reserved for the social domain, beliefs held too weakly to guide decisions where self-interest is directly measurable.

Do these distortions actually pay off socially? A fifth experiment asked naive observers to rate the trustworthiness of Deciders whose choices were presented with fully known social outcomes drawn from the distortion patterns observed earlier. Selfish Deciders whose outcomes implied both options were socially equivalent, the aggregate selfish distortion, were rated significantly more trustworthy than selfish Deciders in any other scenario, including the undistorted midpoint case. Prosocial Deciders likewise earned higher trust ratings when outcomes matched their aggregate distortion, implying a generous sacrifice. Distortion, when it goes undetected, appears to buy reputation, offering a concrete social function for what might otherwise look like mere self-deception.

The most consequential finding came last. In a final experiment, participants saw estimates attributed to a previous participant, an ‘Influencer’, before making their own choices and estimates. When the Influencer’s estimates were selfish-serving, portraying the selfish option as no more harmful than the prosocial one, Followers adopted those estimates and became significantly more likely to choose selfishly themselves, an effect that held against every comparison condition. Prosocial-serving distortions, though sometimes echoed in individual estimates, produced no reliable shift in average estimates or choices. Because fewer than 10 percent of Deciders actually produce the selfish aggregate pattern, a small minority may exert a disproportionate influence on collective beliefs. The authors suggest that information lowering the psychological cost of selfishness appeals to undecided actors in a way that glorified sacrifice does not. In domains from climate mitigation to foreign aid, the study offers a psychological foundation for why polarized views about the impact, rather than merely the value, of our actions take hold: when social consequences are open to interpretation, people may predictably form divergent interpretations, and the most self-serving of them can spread.

Subject of Research: How selfish and prosocial individuals distort estimates of the ambiguous social consequences of their decisions, and how those distortions spread socially

Article Title: Selfish and prosocial individuals both distort their actions’ impact, but selfish distortions can be more contagious

Article References: Vollberg, M. C., & Gross, J. (2026). Selfish and prosocial individuals both distort their actions’ impact, but selfish distortions can be more contagious. Nature Human Behaviour. https://doi.org/10.1038/s41562-026-02585-3

Image Credits: AI Generated

DOI: 10.1038/s41562-026-02585-3

Keywords: social preferences, decision making, motivated reasoning, selfishness, prosocial behaviour, ambiguity, trustworthiness, social contagion, behavioral economics, moral psychology, Nature Human Behaviour, preregistered experiments

The centerpiece of the work is a tightly controlled feeding experiment. Participants consumed an identical standardized carbohydrate meal on separate occasions, once alone and once in the company of a person to whom they felt close. Continuous glucose monitoring revealed that the same food produced a different metabolic story depending on the social context. When participants ate in companionship, their post-meal glucose excursions were smaller, meaning the spike in blood sugar after eating was blunted, and their glucose levels returned to baseline more quickly. In physiological terms, the body needed to deploy less of its regulatory machinery to keep a potentially destabilizing nutrient load under control. Because repeated large glucose swings are implicated in the long arc of metabolic disease, the finding has immediate relevance for one of the most pressing public health challenges of the era.

Crucially, the researchers did not treat this single result as an isolated curiosity. Across a series of preregistered experiments, they tested whether the same proximity effect would appear in other homeostatic domains. It did. When adults were exposed to cold, those who were near a close social partner maintained their temperature regulation more effectively than those tested alone. The pattern also emerged in the earliest stages of life: infants, whose survival depends entirely on the bodies of their caregivers, showed more efficient stress regulation when held or kept in close contact. The consistency of the effect across glucose control, thermoregulation, and stress responsivity is what elevates the work from an interesting observation to a candidate general principle, one that cuts across organ systems that are usually studied in isolation from one another.

Two features of the findings are particularly striking from a technical standpoint. First, the benefits of companionship appeared even without physical touch. Mere proximity to a loved individual was sufficient, suggesting that the relevant signal is not tactile contact or shared heat but something subtler, likely a learned association in which the presence of a specific person predicts safety and reduced physiological demand. Second, the researchers found that the effect was not explained by reductions in subjective stress. This is a critical distinction, because a simpler interpretation of the data would be that companions merely feel calmer, and that calmness secondarily improves metabolic readings. The evidence points instead to a direct regulatory benefit, as if the body recalibrates its operating costs downward when it detects a reliable ally nearby, independent of how stressed the person reports feeling.

Prof. Atzil framed the discovery as a challenge to one of the deepest assumptions in biomedical science. We used to think of the body as an isolated system that regulates itself, she noted, but the findings show that human physiology is inherently social. In her account, being close to someone you love lowers the physical energy the body spends on self-regulation, producing a direct metabolic dividend for togetherness. This framing carries an evolutionary implication that the researchers make explicit: if bodies genuinely run better in company, then social bonding may not be merely a strategy for protection, cooperation, or reproduction layered on top of individual physiology. It may be woven into the very economics of homeostasis, giving organisms a concrete energetic reason to form and maintain attachments in the first place. Human bonds, on this view, are partly metabolic instruments.

The mechanistic story that emerges is one of energetic accounting. Keeping internal conditions stable, a process biologists call homeostasis, is not free. Every correction the body makes, secreting insulin to clear glucose from the bloodstream, shivering or redirecting circulation to defend core temperature, releasing and then dampening stress hormones, consumes energy and imposes wear on tissues. If the nervous system can verify, through continuous monitoring of the social environment, that a protective partner is present, the allostatic load, the cumulative cost of staying ready for threat, can be lowered. The parasympathetic branch of the autonomic nervous system, which favors restorative states, can gain greater influence, and predictive circuits in the brain can downshift their threat forecasts. The result is a body that achieves the same regulatory targets with less expenditure, which is precisely the signature the experiments detected.

The developmental dimension of the work deserves particular emphasis. Infants cannot regulate their own temperature, glucose, or stress responses competently on their own; for most of human evolutionary history, an infant separated from caregivers faced rapid physiological collapse. The finding that infant stress regulation is more efficient in close proximity is therefore unsurprising in outline, but it gains new meaning when read alongside the adult data. It suggests that the social modulation of physiology does not disappear with maturity, as many researchers assumed, but persists throughout life as a quiet background process. The adult eating lunch with a friend and the newborn cradled against a parent may be running variations on the same ancient regulatory program, one in which the presence of a bonded other is counted as an external resource that the body can draw upon to lighten its internal workload.

The public health implications arrive at a moment when dysregulated blood sugar has become a global concern. Rates of type 2 diabetes and prediabetes continue to climb across income levels and continents, and standard advice centers on diet composition, portion control, physical activity, and medication. This study does not overturn any of that guidance, and the researchers are careful to state that social closeness is not a substitute for medical care, nutrition, or exercise. But it does introduce a variable that almost no clinical guideline currently addresses: the identity of the people sitting at the table. If identical meals produce meaningfully different glycemic responses depending on companionship, then epidemiological models of metabolic health that ignore relational context may be systematically missing part of the picture. Blood sugar regulation, as Atzil puts it, is not just about what we eat but who we eat with, and relationships may hold an active biological role in physical wellbeing.

The research design strengthens the credibility of these claims in ways worth noting for readers weighing how much to trust a single headline. The experiments were preregistered, meaning the researchers committed to their hypotheses and analysis plans before collecting data, a safeguard against the selective reporting that has troubled social science in the past. The meal challenge was standardized, removing the obvious confound that shared meals might simply involve different foods. The replication of the effect across distinct physiological domains, and across age groups from infancy to adulthood, makes it unlikely that the result is an artifact of one particular task or population. At the same time, open questions remain. The precise neural and hormonal pathways that translate the perception of a companion into altered insulin dynamics or thermal efficiency have not yet been fully mapped, and future work will need to identify whether oxytocinergic signaling, vagal tone, or other mechanisms carry the signal.

What the study ultimately offers is a revised map of what a human body is. For more than a century, physiology has been practiced largely as the science of the sealed individual, a self-contained machine measured in isolation within laboratory walls. The concept of Social Physiology proposes instead that the boundary of the regulating system extends beyond the skin, into the network of trusted others whose presence the nervous system tracks at all times. Human connection, long celebrated in poetry and studied in psychology as a source of meaning and happiness, now appears in the laboratory as something harder-edged: a measurable reduction in the biological cost of staying alive. The people beside us, the researchers conclude, constitute a powerful and overlooked factor in health, one that operates not through inspiration or encouragement but through the quiet, continuous recalibration of glucose curves, thermal defenses, and stress responses. Relationships, it turns out, do not merely support our emotional lives. They help run the machinery of the body itself.

Subject of Research: The effect of social proximity on human glucose, temperature, and stress regulation

Article Title: Eating with a loved one lowers your blood sugar

Article References: Eating with a loved one lowers your blood sugar. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: social physiology, blood glucose, homeostasis, stress regulation, thermoregulation, metabolic health, Science Advances, Hebrew University of Jerusalem, social bonding, preregistered experiments, infant development, public health

The research tackles a puzzle that has haunted climate communication for years. Collective climate action depends on a public whose beliefs broadly track the scientific consensus, but fallacious information circulates widely on social media, and people frequently misjudge the quality of the arguments they encounter. What has remained unclear is exactly why these failures happen. Three candidate mechanisms compete for attention: partisan identity, which may lead people to protect their group by accepting congenial claims; prior beliefs, which may color judgment regardless of group loyalty; and cognitive limits, which may simply prevent people from detecting reasoning errors even when they want to.

Disentangling these forces is methodologically difficult, because in ordinary discourse they are hopelessly entangled. A climate-skeptic argument is usually encountered by a skeptic, in a context framed by partisans, and it is usually fallacious. Bago and Purcell broke this confound with an experimental protocol that orthogonally manipulated argument quality and argument direction across realistic contexts. Participants evaluated arguments that were either logically valid or built on recognizable fallacies, and that either supported or contradicted mainstream climate positions, while the surrounding context was varied to be neutral or explicitly partisan.

The baseline result is striking. In neutral contexts, prior beliefs dominated judgments of argument strength. People rated arguments consistent with their existing views as stronger, and this belief-driven effect dwarfed the influence of the argument’s actual logical quality. Partisanship mattered too, but its effect was smaller, and the objective quality of the argument—whether it was valid or fallacious—exerted only a modest pull on participants’ assessments. In other words, when judging everyday climate arguments, what people already think about the climate matters far more than whether the argument in front of them actually holds up.

This finding aligns with a growing body of work suggesting that for everyday arguments, prior beliefs play a larger role in perceived argument quality than argument quality itself. It also complicates optimistic accounts of human reasoning, including theories holding that people are naturally adept argument evaluators who, given time and motivation, will converge on logically sound conclusions. In the climate domain, at least, the intuitive response to an argument appears heavily filtered through what the reader already believes to be true.

The more surprising results concern what happens when those arguments appear in hostile partisan territory. Identity-protective models of political cognition predict that embedding an argument in a context where one’s own group is attacked should sharpen motivated reasoning: people should double down on congenial claims and reject hostile ones more vigorously, and their ability to detect logical flaws should deteriorate. That is not what happened. When arguments were embedded in contexts featuring partisan attacks, participants did not show increased partisan bias, and their capacity to discriminate between strong and weak arguments was not impaired.

Instead, something unexpected occurred: partisan attacks reduced participants’ reliance on their prior beliefs. Rather than retreating into their existing positions, people moved away from them when confronted with hostile partisan framing. The authors characterize this pattern as a kind of demotivated responding, visible in their third figure, in which identity threat appears to blunt the drive to defend prior views rather than intensifying it. This stands in tension with the assumption that incivility and intergroup hostility inevitably polarize judgment, an assumption supported by earlier experiments on online partisan criticism. The new data suggest that in the specific task of evaluating argument quality, hostility may disrupt rather than amplify motivated reasoning.

The most practically consequential finding, however, concerns the intervention. In the treatment conditions, participants received a minimal logic warning—an indication that the arguments they were about to evaluate might contain fallacies. This small nudge measurably enhanced discrimination between weak and strong arguments. The warning did not require participants to trust a particular fact-checker, did not tell them what to conclude, and did not touch the substance of climate science at all. It simply prompted them to attend to the logical structure of the claims before them, and that shift was enough to improve performance across belief groups and partisan affiliations.

The result echoes but extends a broader literature on scalable debiasing. Accuracy prompts, which ask people to consider the truthfulness of a headline before sharing it, have proven a replicable tool for reducing misinformation spread, and warning labels from fact-checkers have been shown to work even among people who distrust the fact-checkers themselves. The logic warning tested here differs in a crucial respect: it targets reasoning form rather than factual accuracy. Because it does not adjudicate contested facts, it sidesteps the credibility problem that plagues partisan fact-checking, which may explain why its benefits emerged across the ideological spectrum rather than being confined to one side.

For climate communication, the implications are twofold. First, the diagnosis is more nuanced than the popular narrative of hopeless polarization suggests. Prior beliefs are indeed the dominant filter through which climate arguments are judged, but partisan identity is not the overriding force that identity-protective accounts predict, and hostile partisan environments do not appear to cripple reasoning. Second, and more optimistically, a cheap and content-neutral intervention—a brief note that fallacies may be present—can sharpen the public’s critical faculties. As climate misinformation evolves from outright denial toward subtler attacks on solutions, tools that improve discernment without dictating conclusions may prove among the most durable defenses available. The study’s data and analysis code are publicly available, allowing other researchers to test how far these logic warnings can be pushed, and for whom, as the information environment around climate change continues to deteriorate.

Subject of Research: Psychological mechanisms of climate argument evaluation and the effect of logic warnings on fallacy detection

Article Title: Simple logic warnings improve climate argument evaluation across beliefs and partisanship

Article References: Bago, B., & Purcell, Z. A. (2026). Simple logic warnings improve climate argument evaluation across beliefs and partisanship. Nature Climate Change. https://doi.org/10.1038/s41558-026-02754-2

Image Credits: AI Generated

DOI: 10.1038/s41558-026-02754-2

Keywords: climate change, argument evaluation, logical fallacies, misinformation, prior beliefs, partisanship, motivated reasoning, logic warnings, climate communication, preregistered experiments, debiasing, psychology