Conflict and cooperation in paranoia: a large-scale behavioural experiment

Social identification and paranoia

Paranoia is associated with variation in social behaviour, such as lower inclination to trust others or to behave generously in economic game settings. Such variation may stem, in part, from a reduced tendency to socially identify with others, although previous studies have reported mixed results. We tested whether paranoia involves altered social identification in a pre-registered online study investigating the relationship between a measure of social identification, paranoia, and social behaviours in economic games. We successfully manipulated social identification, but paranoia was associated with slightly increased social identification overall. Neither paranoia nor social identification predicted behaviour in the economic games, and there was no interaction between paranoia and social identification regarding trusting and cooperative behaviours. Our results converge with recent work suggesting that more paranoid individuals may harbour a higher tendency to perceive themselves as having similar beliefs to others. We discuss some key areas for future research to progress understanding in this area.

Measurement invariance of the Revised-Green Paranoid Thought Scale across Black and White Americans

Given the culturally diverse landscape of mental healthcare and research, ensuring that our psychological constructs are measured equivalently across diverse populations is critical. One construct for which there is significant potential for inequitable assessment is paranoia, a prominent feature in psychotic disorders that can also be driven by culture and racial marginalization. This study examined measurement invariance-an analytic technique to rigorously investigate whether a given construct is being measured similarly across groups-of the Revised-Green Paranoid Thought Scale (R-GPTS; Freeman et al., 2021) across Black and White Americans in the general population. Racial group differences in self-reported paranoia were also examined. The analytic sample consisted of 480 non-Hispanic White and 459 non-Hispanic Black Americans. Analyses demonstrated full invariance (i.e., configural, metric, and scalar invariance) of the R-GPTS across groups, indicating that the R-GPTS appropriately captures self-reported paranoia between Black and White Americans. Accordingly, it is reasonable to compare group endorsement: Black participants endorsed significantly higher scores on both the ideas of reference and ideas of persecution subscales of the R-GPTS (Mean ± SD = 10.91 ± 7.12 versus 8.21 ± 7.17 and Mean ± SD = 10.18 ± 10.03 versus 6.35 ± 8.35, for these subscales respectively). Generalized linear modeling revealed that race remained a large and statistically significant predictor of R-GPTS total score (β = -0.38756, p < 0.001) after controlling for relevant demographic factors (e.g., sex, age). This study addresses a critical gap within the existing literature as it establishes that elevations in paranoia exhibited by Black Americans in the R-GPTS reflect actual differences between groups rather than measurement artifacts.

Schizophrenia and Increased Distrust-Based Competitiveness in Interpersonal Interactions: A Serial Process Model

BACKGROUND AND HYPOTHESIS

Game theory paradigms, such as the Prisoner's Dilemma Game (PDG), have been used to study nonclinical paranoia, though research using clinical populations has been scarce. We test our novel theoretical model that schizophrenia leads to competitiveness in interpersonal interactions, and that this link is serially mediated by trait paranoia, state paranoia, and distrust.

STUDY DESIGN

In this quasi-experimental study, individuals with schizophrenia spectrum diagnoses with current persecutory delusions (n = 46) and a nonclinical control group (n = 43) played the PDG, and completed measures of trait paranoia, state paranoia, and distrust.

STUDY RESULTS

Individuals with schizophrenia competed more in the PDG than the control group. Supporting our theoretical model, all direct effects were significant: schizophrenia was associated with higher trait paranoia (H1); trait paranoia predicted state paranoia in the PDG (H2); state paranoia in the PDG predicted distrust of the opponent in the PDG (H3); and distrust predicted competition in the PDG (H4). The hypothesized indirect effect of schizophrenia on competition in the PDG via trait paranoia, state paranoia, and distrust was supported in a serial mediation model (H5).

CONCLUSIONS

The findings make clear theoretical and methodological contributions. We provide the first evidence for a theoretical process model by which schizophrenia leads to competitiveness in interpersonal interactions via trait paranoia, state paranoia, and distrust. Game theory paradigms, and the PDG in particular, are important for advancing theory and research on paranoia as it occurs in both clinical and nonclinical populations.

Paranoid thinking and perceived competitive intention

Paranoid thinking, that others are hostile, can be seen even in the general population. Paranoia is considered the expectation that others are competitors who aim to maximize the differences in payoffs rather than maximize their own payoffs. This study examined whether paranoia reflects the irrational belief that others have a competitive intention and is associated with avoiding perceived competition. We recruited 884 US residents via the Internet and conducted a modified Dictator Game, in which monetary allocation was carried out between the Dictator and the Recipient. The Dictator chooses either fair or competitive allocation while selecting the competitive allocation is irrelevant to increasing the Dictator's payoffs. The Recipient decides whether to accept the Dictator's decision or receive sure but low rewards. We found that Recipients with high-level paranoid thinking expected their opponent to select competitive allocation more than those with low levels, even when selecting it was costly for Dictators. Paranoid thinking was not associated with selecting sure rewards or competitive allocations. The results suggest that paranoia reflects the belief that others have a competitive intention but is not related to avoidance behavior against perceived threats and unilateral attacks.

The computational relationship between reinforcement learning, social inference, and paranoia

Theoretical accounts suggest heightened uncertainty about the state of the world underpin aberrant belief updates, which in turn increase the risk of developing a persecutory delusion. However, this raises the question as to how an agent’s uncertainty may relate to the precise phenomenology of paranoia, as opposed to other qualitatively different forms of belief. We tested whether the same population (n = 693) responded similarly to non-social and social contingency changes in a probabilistic reversal learning task and a modified repeated reversal Dictator game, and the impact of paranoia on both. We fitted computational models that included closely related parameters that quantified the rigidity across contingency reversals and the uncertainty about the environment/partner. Consistent with prior work we show that paranoia was associated with uncertainty around a partner’s behavioural policy and rigidity in harmful intent attributions in the social task. In the non-social task we found that pre-existing paranoia was associated with larger decision temperatures and commitment to suboptimal cards. We show relationships between decision temperature in the non-social task and priors over harmful intent attributions and uncertainty over beliefs about partners in the social task. Our results converge across both classes of model, suggesting paranoia is associated with a general uncertainty over the state of the world (and agents within it) that takes longer to resolve, although we demonstrate that this uncertainty is expressed asymmetrically in social contexts. Our model and data allow the representation of sociocognitive mechanisms that explain persecutory delusions and provide testable, phenomenologically relevant predictions for causal experiments.

What drives beliefs in COVID-19 conspiracy theories? The role of psychotic-like experiences and confinement-related factors

Rationale

The COVID-19 pandemic is a worldwide threat to public health and the global economy. The climate of fear and uncertainty associated with the pandemic has fostered the emergence of a wide range of COVID-19 conspiracy theories that have the potential to shape public opinion and hinder the effective dissemination of valid information. Beliefs in conspiracy theories have been associated with maladaptive personality traits such as schizotypy and paranoia, as well as other non-psychotic psychological characteristics (e.g., social isolation, stress).

Methods

An online survey was conducted to examine the associations between beliefs in COVID-19 conspiracy theories and psychotic-like experiences in a Portuguese community sample (N = 438), while also addressing the role of sociodemographic variables, psychological outcomes (e.g., stress, affective states), confinement-related factors (e.g., confinement conditions/behaviors), and pandemic-related factors (e.g., health concerns, financial issues).

Results

Findings suggest that psychotic-like experiences are associated with beliefs in COVID-19 conspiracy theories, particularly perceptual abnormalities and persecutory ideation. Moreover, increased health-related concerns and reduced education levels also seem to be liability factors for these conspiracy beliefs.

Conclusion

These results add important insights into how the adherence to illogical and erroneous disease-related arguments can be related to psychotic-like experiences. COVID-19 conspiracy theories are yet another major challenge that governments and policymakers must contemplate when defining strategic directions to manage the current and future pandemics.

Trusting and learning from others: immediate and long-term effects of learning from observation and advice

Social learning underpins our species's extraordinary success. Learning through observation has been investigated in several species, but learning from advice-where information is intentionally broadcast-is less understood. We used a pre-registered, online experiment (n = 1492) combined with computational modelling to examine learning through observation and advice. Participants were more likely to immediately follow advice than to copy an observed choice, but this was dependent upon trust in the adviser: highly paranoid participants were less likely to follow advice in the short term. Reinforcement learning modelling revealed two distinct patterns regarding the long-term effects of social information: some individuals relied fully on social information, whereas others reverted to trial-and-error learning. This variation may affect the prevalence and fidelity of socially transmitted information. Our results highlight the privileged status of advice relative to observation and how the assimilation of intentionally broadcast information is affected by trust in others.

Conjecturing Harmful Intent and Preemptive Strike in Paranoia

Paranoia depicts a belief of others having harmful intent. Research using economic games has exhibited the correlation between paranoia and the propensity to characterize ambiguous intentions as harmful. Using a non-clinical sample recruited online from the United States (N=290), we examined whether paranoid thoughts influence aggressive behavior against the subjective perception of harmful intent. We conducted a preemptive strike game wherein aggressive behavior was assumed to be guided by the fear of an opponent. The outcomes indicate that (1) individuals with high paranoia assume harmful intent of an opponent more than those with low paranoia (2) conjecturing an opponent's harmful intent predicted an increase in the probability of a preemptive strike, and (3) paranoia did not have a statistically significant effect on encouraging a preemptive strike. Additionally, the exploratory analysis revealed that paranoia was related to participant's aggressiveness and with suppositions of other's self-interests and competitiveness. This study presents empirical evidence that paranoia is related to the perception of social threats in an uncertain situation. We discuss the possibility that paranoid ideation can promote or inhibit a preemptive strike.

The revised Green et al., Paranoid Thoughts Scale (R-GPTS): psychometric properties, severity ranges, and clinical cut-offs

BACKGROUND

The Green et al., Paranoid Thoughts Scale (GPTS) - comprising two 16-item scales assessing ideas of reference (Part A) and ideas of persecution (Part B) - was developed over a decade ago. Our aim was to conduct the first large-scale psychometric evaluation.

METHODS

In total, 10 551 individuals provided GPTS data. Four hundred and twenty-two patients with psychosis and 805 non-clinical individuals completed GPTS Parts A and B. An additional 1743 patients with psychosis and 7581 non-clinical individuals completed GPTS Part B. Factor analysis, item response theory, and receiver operating characteristic analyses were conducted.

RESULTS

The original two-factor structure of the GPTS had an inadequate model fit: Part A did not form a unidimensional scale and multiple items were locally dependant. A Revised-GPTS (R-GPTS) was formed, comprising eight-item ideas of reference and 10-item ideas of persecution subscales, which had an excellent model fit. All items in the new Reference (a = 2.09-3.67) and Persecution (a = 2.37-4.38) scales were strongly discriminative of shifts in paranoia and had high reliability across the spectrum of severity (a > 0.90). The R-GPTS score ranges are: average (Reference: 0-9; Persecution: 0-4); elevated (Reference: 10-15; Persecution: 5-10); moderately severe (Reference: 16-20; Persecution:11-17); severe (Reference: 21-24; Persecution: 18-27); and very severe (Reference: 25+; Persecution: 28+). Recommended cut-offs on the persecution scale are 11 to discriminate clinical levels of persecutory ideation and 18 for a likely persecutory delusion.

CONCLUSIONS

The psychometric evaluation indicated a need to improve the GPTS. The R-GPTS is a more precise measure, has excellent psychometric properties, and is recommended for future studies of paranoia.

Social reward, punishment, and prosociality in paranoia

Paranoia is the exaggerated belief that harm will occur and is intended by others. Although commonly framed in terms of attributing malicious intent to others, recent work has explored how paranoia also affects social decision-making, using economic games. Previous work found that paranoia is associated with decreased cooperation and increased punishment in the Dictator Game (where cooperating and punishing involve paying a cost to respectively increase or decrease a partner's income). These findings suggest that paranoia might be associated with variation in subjective reward from positive and/or negative social decision-making, a possibility we explore using a preregistered experiment with U.S.-based participants (n = 2,004). Paranoia was associated with increased self-reported enjoyment of negative social interactions and decreased self-reported enjoyment of prosocial interactions. More paranoid participants attributed stronger harmful intent to a partner. Harmful intent attributions and the enjoyment of negative social interactions positively predicted the tendency to pay to punish the partner. Cooperation was positively associated with the tendency to enjoy prosocial interactions and increased with participant age. There was no main effect of paranoia on tendency to cooperate in this setting. We discuss these findings in light of previous research. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Reduction in social learning and increased policy uncertainty about harmful intent is associated with pre-existing paranoid beliefs: Evidence from modelling a modified serial dictator game

Current computational models suggest that paranoia may be explained by stronger higher-order beliefs about others and increased sensitivity to environments. However, it is unclear whether this applies to social contexts, and whether it is specific to harmful intent attributions, the live expression of paranoia. We sought to fill this gap by fitting a computational model to data (n = 1754) from a modified serial dictator game, to explore whether pre-existing paranoia could be accounted by specific alterations to cognitive parameters characterising harmful intent attributions. We constructed a ‘Bayesian brain’ model of others’ intent, which we fitted to harmful intent and self-interest attributions made over 18 trials, across three different partners. We found that pre-existing paranoia was associated with greater uncertainty about other’s actions. It moderated the relationship between learning rates and harmful intent attributions, making harmful intent attributions less reliant on prior interactions. Overall, the magnitude of harmful intent attributions was directly related to their uncertainty, and importantly, the opposite was true for self-interest attributions. Our results explain how pre-existing paranoia may be the result of an increased need to attend to immediate experiences in determining intentional threat, at the expense of what is already known, and more broadly, they suggest that environments that induce greater probabilities of harmful intent attributions may also induce states of uncertainty, potentially as an adaptive mechanism to better detect threatening others. Importantly, we suggest that if paranoia were able to be explained exclusively by core domain-general alterations we would not observe differential parameter estimates underlying harmful-intent and self-interest attributions.

A great deal of work has tried to explain paranoia through general cognitive principles, although relatively little has tried to understand whether paranoia may be explained by specific changes to social learning processes. This question is crucial, as paranoia is inherently a social phenomenon, and requires mechanistic explanations to match with its dynamic phenomenology. In this paper we wanted to test whether pre-existing and live paranoid beliefs about others specifically altered how an individual attributed harmful intent–the live expression of paranoia–to partners over a series of live interactions. To do this we applied a novel computational model and network analysis to behavioural data from a large sample of participants in the general population that had played a modified Dictator game online, and required them to attribute whether the behaviour of their partner was due to their intent to harm, or their self-interest, on two mutually exclusive scales. Pre-existing paranoid beliefs about others reduced the value of new partner behaviours on evolving attributions of harmful intent. We suggest that both pre-existing paranoid beliefs and momentary paranoia may incur an adaptive cognitive state to better track potentially threatening others, and demonstrate phenomenological specificity associated with mechanisms of live paranoia.

Paranoia as a deficit in non-social belief updating

Paranoia is the belief that harm is intended by others. It may arise from selective pressures to infer and avoid social threats, particularly in ambiguous or changing circumstances. We propose that uncertainty may be sufficient to elicit learning differences in paranoid individuals, without social threat. We used reversal learning behavior and computational modeling to estimate belief updating across individuals with and without mental illness, online participants, and rats chronically exposed to methamphetamine, an elicitor of paranoia in humans. Paranoia is associated with a stronger prior on volatility, accompanied by elevated sensitivity to perceived changes in the task environment. Methamphetamine exposure in rats recapitulates this impaired uncertainty-driven belief updating and rigid anticipation of a volatile environment. Our work provides evidence of fundamental, domain-general learning differences in paranoid individuals. This paradigm enables further assessment of the interplay between uncertainty and belief-updating across individuals and species.

Everyone has had fleeting concerns that others might be against them at some point in their lives. Sometimes these concerns can escalate into paranoia and become debilitating. Paranoia is a common symptom in serious mental illnesses like schizophrenia. It can cause extreme distress and is linked with an increased risk of violence towards oneself or others. Understanding what happens in the brains of people experiencing paranoia might lead to better ways to treat or manage it.

Some experts argue that paranoia is caused by errors in the way people assess social situations. An alternative idea is that paranoia stems from the way the brain forms and updates beliefs about the world. Now, Reed et al. show that both people with paranoia and rats exposed to a paranoia-inducing substance expect the world will change frequently, change their minds often, and have a harder time learning in response to changing circumstances.

In the experiments, human volunteers with and without psychiatric disorders played a game where the best choices change. Then, the participants completed a survey to assess their level of paranoia. People with higher levels of paranoia predicted more changes would occur and made less predictable choices. In a second set of experiments, rats were put in a cage with three holes where they sometimes received sugar rewards. Some of the rats received methamphetamine, a drug that causes paranoia in humans. Rats given the drug also expected the location of the sugar reward would change often. The drugged animals had harder time learning and adapting to changing circumstances.

The experiments suggest that brain processes found in both rats, which are less social than humans, and humans contribute to paranoia. This suggests paranoia may make it harder to update beliefs. This may help scientists understand what causes paranoia and develop therapies or drugs that can reduce paranoia. This information may also help scientists understand why during societal crises like wars or natural disasters humans are prone to believing conspiracies. This is particularly important now as the world grapples with climate change and a global pandemic. Reed et al. note paranoia may impede the coordination of collaborative solutions to these challenging situations.

Paranoia, sensitization and social inference: findings from two large-scale, multi-round behavioural experiments

The sensitization model suggests that paranoia is explained by over-sensitivity to social threat. However, this has been difficult to test experimentally. We report two preregistered social interaction studies that tested (i) whether paranoia predicted overall attribution and peak attribution of harmful intent and (ii) whether anxiety, interpersonal sensitivity and worry predicted the attribution of harmful intent. In Study 1, we recruited a large general population sample (N = 987) who serially interacted with other participants in multi-round dictator games and matched to fair, partially fair or unfair partners. Participants rated attributions of harmful intent and self-interest after each interaction. In Study 2 (N = 1011), a new sample of participants completed the same procedure and additionally completed measures of anxiety, worry and interpersonal sensitivity. As predicted, prior paranoid ideation was associated with higher and faster overall harmful intent attributions, whereas attributions of self-interest were unaffected, supporting the sensitization model. Contrary to predictions, neither worry, interpersonal sensitivity nor anxiety was associated with harmful intent attributions. In a third exploratory internal meta-analysis, we combined datasets to examine the effect of paranoia on trial-by-trial attributional changes when playing fair and unfair dictators. Paranoia was associated with a greater reduction in harmful intent attributions when playing a fair but not unfair dictator, suggesting that paranoia may also exaggerate the volatility of beliefs about the harmful intent of others.

Inflexible social inference in individuals with subclinical persecutory delusional tendencies

It has been suspected that abnormalities in social inference (e.g., learning others' intentions) play a key role in the formation of persecutory delusions (PD). In this study, we examined the association between subclinical PD and social inference, testing the prediction that proneness to PD is related to altered social inference and beliefs about others' intentions. We included 151 participants scoring on opposite ends of Freeman's Paranoia Checklist (PCL). The participants performed a probabilistic advice-taking task with a dynamically changing social context (volatility) under one of two experimental frames. These frames differentially emphasised possible reasons behind unhelpful advice: (i) the adviser's possible intentions (dispositional frame) or (ii) the rules of the game (situational frame). Our design was thus 2 × 2 factorial (high vs. low delusional tendencies, dispositional vs. situational frame). We found significant group-by-frame interactions, indicating that in the situational frame high PCL scorers took advice less into account than low scorers. Additionally, high PCL scorers believed more frequently that incorrect advice was delivered intentionally and that such misleading behaviour was directed towards them personally. Overall, our results suggest that social inference in individuals with subclinical PD tendencies is shaped by negative prior beliefs about the intentions of others and is thus less sensitive to the attributional framing of adviser-related information. These findings may help future attempts of identifying individuals at risk for developing psychosis and understanding persecutory delusions in psychosis.

Paranoia and conspiracy: group cohesion increases harmful intent attribution in the Trust Game

Current theories argue that hyper-sensitisation of social threat perception is central to paranoia. Affected people often also report misperceptions of group cohesion (conspiracy) but little is known about the cognitive mechanisms underpinning this conspiracy thinking in live interactions. In a pre-registered experimental study, we used a large-scale game theory approach (N > 1,000) to test whether the social cohesion of an opposing group affects paranoid attributions in a mixed online and lab-based sample. Participants spanning the full population distribution of paranoia played as proposers in a modified Trust Game: they were allocated a bonus and chose how much money to send to a pair of responders which was quadrupled before reaching these responders. Responders decided how much to return to the proposers through the same process. Participants played in one of two conditions: against a cohesive group who communicated and arrived at a joint decision, or a non-cohesive group who made independent decisions. After the exchange, proposers rated the extent to which the responders’ decisions were driven by (i) self-interest and (ii) intent to harm. Although the true motives are ambiguous, cohesive responders were reliably rated by participants as being more strongly motivated by intent to harm, indicating that group cohesion affects social threat perception. Highly paranoid participants attributed harmful intent more strongly overall but were equally reactive to social cohesion as other participants. This suggests that paranoia involves a generally lowered threshold for social threat detection but with an intact sensitivity for cohesion-related group characteristics.

Paranoia and conspiracy: group cohesion increases harmful intent attribution in the Trust Game

Current theories argue that hyper-sensitisation of social threat perception is central to paranoia. Affected people often also report misperceptions of group cohesion (conspiracy) but little is known about the cognitive mechanisms underpinning this conspiracy thinking in live interactions. In a pre-registered experimental study, we used a large-scale game theory approach (N > 1,000) to test whether the social cohesion of an opposing group affects paranoid attributions in a mixed online and lab-based sample. Participants spanning the full population distribution of paranoia played as proposers in a modified Trust Game: they were allocated a bonus and chose how much money to send to a pair of responders which was quadrupled before reaching these responders. Responders decided how much to return to the proposers through the same process. Participants played in one of two conditions: against a cohesive group who communicated and arrived at a joint decision, or a non-cohesive group who made independent decisions. After the exchange, proposers rated the extent to which the responders' decisions were driven by (i) self-interest and (ii) intent to harm. Although the true motives are ambiguous, cohesive responders were reliably rated by participants as being more strongly motivated by intent to harm, indicating that group cohesion affects social threat perception. Highly paranoid participants attributed harmful intent more strongly overall but were equally reactive to social cohesion as other participants. This suggests that paranoia involves a generally lowered threshold for social threat detection but with an intact sensitivity for cohesion-related group characteristics.

An evolutionary perspective on paranoia

Paranoia is the most common symptom of psychosis but paranoid concerns occur throughout the general population. Here, we argue for an evolutionary approach to paranoia across the spectrum of severity that accounts for its complex social phenomenology - including the perception of conspiracy and selective identification of perceived persecutors - and considers how it can be understood in light of our evolved social cognition. We argue that the presence of coalitions and coordination between groups in competitive situations could favour psychological mechanisms that detect, anticipate and avoid social threats. Our hypothesis makes testable predictions about the environments in which paranoia should be most common as well as the developmental trajectory of paranoia across the lifespan. We suggest that paranoia should not solely be viewed as a pathological symptom of a mental disorder but also as a part of a normally-functioning human psychology.

Moral Emotions and Social Economic Games in Paranoia

Impaired social cognitive processes are putative psychological mechanisms implicated in the formation and maintenance of paranoid beliefs. Paranoia denotes unfounded fears about the hostile intentions of others and is prevalent in a significant proportion of the general population. We investigated social cognition in healthy participants selectively recruited to have a broad occurrence of paranoid thinking (n = 89). Participants completed a novel computerized task of moral emotions and two social economic exchange games (Prisoner's Dilemma, Ultimatum Game) from the EMOTICOM neuropsychological test battery. Regression analyses revealed that delusional ideation predicted shameful feelings when the victim of deliberate harm by another person. Cooperative behavior on the Prisoner's Dilemma was greatest when the participant and opponent contributed equally to joint earnings. Participants demonstrated significantly more punishment behavior when contributions were unequal and stole more from the opponent using a suspicious strategy of gameplay. In addition, paranoid thinking was positively associated with more stealing from the cooperative opponent. On the Ultimatum Game, participants accepted significantly more unequal offers when the opponent contributed more and sensitivity to fairness was greatest when the participant contributed more. These data demonstrate that delusional ideation predicts a maladaptive emotional response to interpersonal harm and that paranoid thinking may lead to reduced cooperation toward mutual reward. The effects of paranoia on moral emotions and pro-social behavior at more severe levels of persecutory thinking warrant further investigation.

Experimentally induced social threat increases paranoid thinking

The ability to attribute intentions to others is a hallmark of human social cognition but is altered in paranoia. Paranoia is the most common positive symptom of psychosis but is also present to varying degrees in the general population. Epidemiological models suggest that psychosis risk is associated with low social rank and minority status, but the causal effects of status and group affiliation on paranoid thinking remain unclear. We examined whether relative social status and perceived group affiliation, respectively, affect live paranoid thinking using two large-N (N = 2030), pre-registered experiments. Interacting with someone from a higher social rank or a political out-group led to an increase in paranoid attributions of harmful intent for ambiguous actions. Pre-existing paranoia predicted a general increase in harmful intent attribution, but there was no interaction with either type of social threat: highly paranoid people showed the same magnitude of increase as non-paranoid people, although from a higher baseline. We conclude social threat in the form of low social status and out-group status affects paranoid attributions, but ongoing paranoia represents a lowered threshold for detecting social threat rather than an impaired reactivity to it.

Conflict and cooperation in paranoia: a large-scale behavioural experiment

BACKGROUND

Paranoia involves thoughts and beliefs about the harmful intent of others but the social consequences have been much less studied. We investigated whether paranoia predicts maladaptive social behaviour in terms of cooperative and punitive behaviour using experimental game theory paradigms, and examined whether reduced cooperation is best explained in terms of distrust as previous studies have claimed.

METHODS

We recruited a large population sample (N = 2132) online. All participants completed the Green et al. Paranoid Thoughts Scale and (i) a Dictator Game and (ii) an Ultimatum Game, the former with an option for costly punishment. Following distrust-based accounts, we predicted highly paranoid people would make higher offers when the outcome depended on receiving a positive response from their partner (Ultimatum Game) but no difference when the partner's response was irrelevant (Dictator Game). We also predicted paranoia would increase punitive responses. Predictions were pre-registered in advance of data collection. Data and materials are open access.

RESULTS

Highly paranoid participants actually made lower offers than non-paranoid participants both in the Dictator Game and in the Ultimatum Game. Paranoia positively predicted punitive responses.

CONCLUSIONS

These findings suggest that distrust is not the best explanation for reduced cooperation in paranoia and alternative explanations, such as increased self-interest, may apply. However, the tendency to attribute harmful intent to partners was important in motivating punitive responses. These results highlight differing motivations underlying adverse social behaviour in paranoia and suggest that accounts based solely on the presenting features of paranoia may need to be rethought.

Do patients with different psychiatric disorders show altered social decision-making? A systematic review of ultimatum game experiments in clinical populations

BACKGROUND

Impairments in social functioning are a common feature of psychiatric disorders. Game paradigms pose a unique way for studying how people make decisions in interpersonal contexts. In the last decade, researchers have started to use these paradigms to study social decision-making in patients with psychiatric disorders.

PURPOSE

The aim of this systematic literature review is to summarise the currently available evidence on the behaviour of patients with psychiatric disorders in the commonly used Ultimatum Game (UG).

METHOD

A systematic literature search including MEDLINE, PsycINFO, PSYNDEXplus Tests, PSYNDEXPLUS Literature, EBM Reviews-Cochrane Central Register of Controlled Trials, Embase and PASCAL was performed via the Ovid interface.

RESULTS

We found evidence for alterations in UG behaviour for patients with frontotemporal dementia, schizophrenia, affective disorders, alcohol, cocaine, heroin and 3,4-methylenedioxymethamphetamine consumption, alcohol dependence, anxiety disorders, borderline personality disorder, autism, Tourette syndrome and oppositional defiant disorder.

CONCLUSION

There is some evidence that different psychiatric disorders might go along with alterations in social decision-making. However, in general, data are currently limited and studies are hard to compare due to differences in methodologies.

Quantitative account of social interactions in a mental health care ecosystem: cooperation, trust and collective action

Mental disorders have an enormous impact in our society, both in personal terms and in the economic costs associated with their treatment. In order to scale up services and bring down costs, administrations are starting to promote social interactions as key to care provision. We analyze quantitatively the importance of communities for effective mental health care, considering all community members involved. By means of citizen science practices, we have designed a suite of games that allow to probe into different behavioral traits of the role groups of the ecosystem. The evidence reinforces the idea of community social capital, with caregivers and professionals playing a leading role. Yet, the cost of collective action is mainly supported by individuals with a mental condition - which unveils their vulnerability. The results are in general agreement with previous findings but, since we broaden the perspective of previous studies, we are also able to find marked differences in the social behavior of certain groups of mental disorders. We finally point to the conditions under which cooperation among members of the ecosystem is better sustained, suggesting how virtuous cycles of inclusion and participation can be promoted in a 'care in the community' framework.