When and why do people avoid unknown probabilities in decisions under uncertainty? Testing some predictions from optimal foraging theory

Learning about successfully implemented sustainability policies abroad increases support for sustainable domestic policies

Anthropogenic climate change poses an existential threat to life on Earth, hastening the need to generate support for sustainability policies. Four preregistered studies (total N = 2524) tested whether informing United States citizens about the successful implementation of sustainability policies abroad increased support for similar domestic policies. Studies 1 and 2 found that learning about the successful implementation of sustainability policies (reducing automobile use, using wind energy) abroad increased (1) support for similar domestic policies, (2) intentions to modify behavior to facilitate the adoption of sustainability policies, and (3) behavioral support for sustainability policies. Study 3 found that learning about sustainability policies in both WEIRD (Western, Educated, Industrialized, Rich, Democratic) (France) and non-WEIRD (Colombia) countries increased support for similar domestic policies. Study 4 found that learning about sustainability policies abroad increased support for domestic policy proposals that would impact participants' city of residence. Overall, these findings suggest that educating citizens about the implementation of sustainability policies abroad can bolster support for domestic policies that combat climate change.

Keep your budget together! Investigating determinants on risky decision-making about losses

The present study investigates the influence of framing, different amounts to lose, and probabilities of a risky and sure choice option, time limits, and need on risky decision-making. For a given block of trials, participants were equipped with a personal budget (number of points). On each trial within a block, a specific initial amount is possibly taken from the budget by the outcome of a gamble or the choice of a sure loss option. The goal was to avoid losing points from the budget for not falling below a predefined need threshold. Three different levels of induced need were included. Employing a psychophysical experimental approach, we furthermore tested a sequential component of human risk behavior towards a need threshold inspired by research on animal foraging behavior. Risk-sensitivity models and the Stone-Geary framework serve as generating hypotheses on need thresholds. We found that framing, need, and probabilities influenced risky choices. Time limits and initial amounts moderated the framing effect. No sequential component was observed.

A review of risky decision-making in psychosis-spectrum disorders

The investigation of risky decision-making has a prominent place in clinical science, with sundry behavioral tasks aimed at empirically quantifying the psychological construct of risk-taking. However, use of differing behavioral tasks has resulted in lack of agreement on risky decision-making within psychosis-spectrum disorders, as findings fail to converge upon the typical, binary conceptualization of increased risk-seeking or risk-aversion. The current review synthesizes the behavioral, risky decision-making literature to elucidate how specific task parameters may contribute to differences in task performance, and their associations with psychosis symptomatology and cognitive functioning. A paring of the literature suggests that: 1) Explicit risk-taking may be characterized by risk imperception, evidenced by less discrimination between choices of varying degrees of risk, potentially secondary to cognitive deficits. 2) Ambiguous risk-taking findings are inconclusive with few published studies. 3) Uncertain risk-taking findings, consistently interpreted as more risk-averse, have not parsed risk attitudes from confounding processes that may impact decision-making (e.g. risk imperception, reward processing, motivation). Thus, overgeneralized interpretations of task-specific risk-seeking/aversion should be curtailed, as they may fail to appropriately characterize decision-making phenomena. Future research in psychosis-spectrum disorders would benefit from empirically isolating contributions of specific processes during risky decision-making, including the newly hypothesized risk imperception.

Deriving Features of Religions in the Wild : How Communication and Threat-Detection May Predict Spirits, Gods, Witches, and Shamans

Religions "in the wild" are the varied set of religious activities that occurred before the emergence of organized religions with doctrines, or that persist at the margins of those organized traditions. These religious activities mostly focus on misfortune; on how to remedy specific cases of illness, accidents, failures; and on how to prevent them. I present a general model to account for the cross-cultural recurrence of these particular themes. The model is based on (independently established) features of human psychology-namely, (a) epistemic vigilance, the set of systems whereby we evaluate the quality of information and of sources of information, and (b) threat-detection psychology, the set of evolved systems geared at detecting potential danger in the environment. Given these two sets of systems, the dynamics of communication will favor particular types of messages about misfortune. This makes it possible to predict recurrent features of religious systems, such as the focus on nonphysical agents, the focus on particular cases rather than general aspects of misfortune, and the emergence of specialists. The model could illuminate not just why such representations are culturally successful, but also why people are motivated to formulate them in the first place.

Is a Rational Politics of Disaster Possible? Making Useful Decisions for Others in an Experimental Disaster Game

Disaster responses are political. But can citizens make useful disaster decisions? Potential obstacles are that such decisions are complex, involve public goods, and often affect other people. Theories of political decision-making disagree on whether these problems can be overcome. We used experimental economic games that simulate disaster to test whether people are willing and able to prevent disasters for others. Groups of players face a complex task in which options that might help vary in their riskiness. Importantly, although all options are reasonable, which option is most useful depends on the experimental condition. We find that players will pay to help, can identify which option is most useful across experimental conditions, and will pay to learn how best to help. Thus, players were able to make useful and costly decisions to prevent others from experiencing disaster. This suggests that, in at least some situations, citizens may be able to make good disaster decisions.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11109-021-09700-2.

Analysis of the relationship between psychological gender and risk perception style and attitudes towards safety in a group of women and men

The aim of the research was to analyse the relationship between psychological gender and risk perception style and the manifestation of pro-safe attitudes. The study involved 507 people in the age range 20-64 years, including 257 women and 250 men. Variables were measured using the following methods: Znajmiecka-Sikora's questionnaire of attitudes towards safety (PwB), Zaleśkiewicz's questionnaire of the individual risk perception style (SIRI) and Lipińska-Grobelny and Gorczycka's scale of masculinity and femininity (SMiK). The obtained results prove that psychological gender significantly differentiates risk perception style and attitudes towards safety. The feminine dimension has been shown to strengthen safe attitudes and minimize risk-taking, while the masculine dimension weakens attitudes towards safety and strengthens risk propensity.

Neural Dynamics Underlying the Evaluation Process of Ambiguous Options During Reward-Related Decision-Making

Ambiguous decision-making involves different processes. However, few studies have focused on the evaluation process. In this study, event-related potentials (ERPs) and event-related spectrum perturbation (ERSP) techniques were used to explore the neural dynamics underlying the evaluation process of ambiguous options through an ambiguous choice task. Some important results emerged. We found a preference for lotteries with low ambiguity regardless of reward amount, suggesting that subjects were averse to ambiguity in our paradigm. Our electroencephalography (EEG) results clarified the neural dynamics underlying the evaluation process. In the time domain, lotteries with both a larger reward and lower ambiguity elicited a larger P3. In the time-frequency domain, larger amplitudes of delta activity at 200–400 ms and 500–600 ms post-stimulus were elicited by lotteries with low ambiguity. Moreover, lotteries with a larger reward elicited larger amplitudes of delta activity at 400–600 ms post-stimulus. Our ERPs and ERSP results suggested that individuals in our paradigm evaluated ambiguity and reward separately, and then integrated their evaluation to form subjective values of different lotteries.

State-dependent risk-taking

Who takes risks, and when? The relative state model proposes two non-independent selection pressures governing risk-taking: need-based and ability-based. The need-based account suggests that actors take risks when they cannot reach target states with low-risk options (consistent with risk-sensitivity theory). The ability-based account suggests that actors engage in risk-taking when they possess traits or abilities that increase the expected value of risk-taking (by increasing the probability of success, enhancing payoffs for success or buffering against failure). Adaptive risk-taking involves integrating both considerations. Risk-takers compute the expected value of risk-taking based on their state-the interaction of embodied capital relative to one's situation, to the same individual in other circumstances or to other individuals. We provide mathematical support for this dual pathway model, and show that it can predict who will take the most risks and when (e.g. when risk-taking will be performed by those in good, poor, intermediate or extreme state only). Results confirm and elaborate on the initial verbal model of state-dependent risk-taking: selection favours agents who calibrate risk-taking based on implicit computations of condition and/or competitive (dis)advantage, which in turn drives patterned individual differences in risk-taking behaviour.

Why the Uncertain Term Occurs in the Farmland Lease Market: Evidence from Rural China

Urbanization and aging of the agricultural population lead to the insufficient supply of agricultural labor and land being idle in rural China, calling for the farmland lease market to maintain sustainable and efficient use of farmland. However, rural households tend to agree on an uncertain term for farmland leasing in/out, which leads to low efficiency and land loss in agriculture. Therefore, using the survey data collected from 2704 rural households and a logistic regression model, we examine the effects of risk faced by the rural households on the likelihood of the uncertain term for farmland leasing. Results reveal that a large share of labor with low education and high income increase the likelihood of an uncertain term for farmland leasing out activities, while a high disaster frequency, a high education of household and a high share of agricultural income increase the probability of an uncertain term for farmland leasing in activities. Additionally, leasing farmland to/from relatives or neighbors, informal contracts, low rent and the lack of pension insurance also increase the likelihood of the uncertain term for farmland leasing out/in activities. Findings suggest that more attention should be paid to education, agricultural insurance and social security system in rural areas.

An investigation of the probability of reciprocation in a risk-reduction model of sharing

A laboratory study investigated whether reductions in the probability of reciprocation would influence sharing in situations of shortfall risk. Choice in twelve adults was evaluated against the predictions of a risk-reduction model of sharing derived from a risk-sensitive foraging theory (the energy-budget rule). Participants responded on a computer task to earn hypothetical money which could be later exchanged for real money. If participants selected the sharing option, their earnings were pooled and split with a (fictitious) partner. To model shortfall risk, the task was arranged so that participants lost their accumulated earnings if it fell below an earnings requirement. Across conditions the probability that the partner would contribute to the pool was .95, .65, and 0. Choosing the sharing option was optimal under the .95 and .65, but not 0 condition. Although levels of preference for the sharing option were below optimal, participants chose it significantly more in the .95 and .65 conditions than in the 0 condition. Sharing was lower in the .65 condition than .95 condition but the difference was not statically significant. The results are consistent with prior cooperation research and demonstrate that under shortfall risk, reductions in the probability of reciprocation by partners may decrease sharing.

Ambiguous games: Evidence for strategic ambiguity aversion

The problem of ambiguity in games is discussed, and a class of ambiguous games is identified. A total of 195 participants played strategic-form games of various sizes with unidentified co-players. In each case, they first chose between a known-risk game involving a co-player indifferent between strategies and an equivalent ambiguous game involving one of several co-player types, each with a different dominant strategy, and then they chose a strategy for the preferred game. Half the players knew that the ambiguous co-player types were equally likely, and half did not. Half expected the outcomes to be known immediately, and half expected a week's delay. Known-risk games were generally preferred, confirming a significant strategic ambiguity aversion effect. In the delay conditions, players who knew that the ambiguous co-player types were equally likely were significantly less ambiguity averse than those who did not. Decision confidence was significantly higher in 2 × 2 than in larger games.

Examining the Priority Heuristic in Conditions of Resource Need Levels

Within the domain of risky decision making, there are a number of predictive models which are consistent with the hypothesis that human minds are molded for specific behavioral patterns based on environmental cues. Two models are the priority heuristic and risk sensitive foraging. Using a modified version of the traditional risky choice gambles paradigm, a study was designed to tease apart specific predictions made by each of these two models. It was discovered that the best explanation for choice behavior was consistent with risk sensitive foraging. This was true for risky preferences in gambles. Also, decision time predictions from the priority heuristic were not supported. Collectively, this may show additional support for risk-sensitivity driving some human behaviors. It may also carve out the boundaries for the proper "ecology" of the priority heuristic.

Gambling, Risk-Taking, and Antisocial Behavior: A Replication Study Supporting the Generality of Deviance

Research suggests that high frequency gambling is a component of the "generality of deviance", which describes the observation that various forms of risky and antisocial behavior tend to co-occur among individuals. Furthermore, risky and antisocial behaviors have been associated with such personality traits as low self-control, and impulsivity, and sensation-seeking. We conducted a replication (and extension) of two previous studies examining whether high frequency gambling is part of the generality of deviance using a large and diverse community sample (n = 328). This study was conducted as a response to calls for more replication studies in the behavioral and psychological sciences (recent systematic efforts suggest that a significant proportion of psychology studies do not replicate). The results of the present study largely replicate those previously found, and in many cases, we observed stronger associations among measures of gambling, risk-taking, and antisocial behavior in this diverse sample. Together, this study provides evidence for the generality of deviance inclusive of gambling (and, some evidence for the replicability of research relating to gambling and individual differences).

Tolerance of Ambiguity: Text Analytic vs Self-Report Measures in Two Nonclinical Groups

Avoidance of ambiguity can be examined by both text analytic and self-report methods. In previous studies using text analytic methods, clinical groups showed a higher avoidance of ambiguity than nonclinical subjects. In nonclinical subjects, however, higher avoidance of ambiguity did not correlate with emotional processes. In these studies, higher avoidance of ambiguity was assessed by a text analytic method (DoTA), which was applied to the Holtzman Inkblot Technique. However, the Inkblot Technique may not activate those cognitive-affective structures in nonclinical subjects required to elicit higher avoidance of ambiguity. Thus, the following discrepant results can be predicted: in nonclinical subjects, DoTA indicators of higher avoidance of ambiguity based on Holtzman Inkblot Technique do not show correlations with self-report measures of higher avoidance of ambiguity such as the Ambiguity Tolerance Questionnaire, the Inventory for the Measurement of Tolerance of Ambiguity (Reis inventory), or self-report measures of related traits of personality such as the Giessen Test. Self-report measures of higher avoidance of ambiguity should show such correlations. Two studies were carried out to test these hypotheses. In Study 1, 80 nonclinical subjects (48 women, M age = 34.5 yr.) were examined using the DoTA text analytic method, the Ambiguity Tolerance Questionnaire-14 and the Giessen Test. In Study 2, 82 nonclinical subjects (43 women, M age = 34.0 yr.) were tested using the Reis inventory. The results obtained in these subjects are consistent with the hypothesis.

The Relative State Model: Integrating Need-Based and Ability-Based Pathways to Risk-Taking

Who takes risks, and why? Does risk-taking in one context predict risk-taking in other contexts? We seek to address these questions by considering two non-independent pathways to risk: need-based and ability-based. The need-based pathway suggests that risk-taking is a product of competitive disadvantage consistent with risk-sensitivity theory. The ability-based pathway suggests that people engage in risk-taking when they possess abilities or traits that increase the probability of successful risk-taking, the expected value of the risky behavior itself, and/or have signaling value. We provide a conceptual model of decision-making under risk-the relative state model-that integrates both pathways and explicates how situational and embodied factors influence the estimated costs and benefits of risk-taking in different contexts. This model may help to reconcile long-standing disagreements and issues regarding the etiology of risk-taking, such as the domain-generality versus domain-specificity of risk or differential engagement in antisocial and non-antisocial risk-taking.

P300 and Decision Making under Risk and Ambiguity

Our study aims to contrast the neural temporal features of early stage of decision making in the context of risk and ambiguity. In monetary gambles under ambiguous or risky conditions, 12 participants were asked to make a decision to bet or not, with the event-related potentials (ERPs) recorded meantime. The proportion of choosing to bet in ambiguous condition was significantly lower than that in risky condition. An ERP component identified as P300 was found. The P300 amplitude elicited in risky condition was significantly larger than that in ambiguous condition. The lower bet rate in ambiguous condition and the smaller P300 amplitude elicited by ambiguous stimuli revealed that people showed much more aversion in the ambiguous condition than in the risky condition. The ERP results may suggest that decision making under ambiguity occupies higher working memory and recalls more past experience while decision making under risk mainly mobilizes attentional resources to calculate current information. These findings extended the current understanding of underlying mechanism for early assessment stage of decision making and explored the difference between the decision making under risk and ambiguity.

Inequality and Risk-Taking

Inequality has been associated with risk-taking at the societal level. However, this relationship has not been directly investigated at the individual level. Risk-sensitivity theory predicts that decision makers should increase risk-taking in situations of disparity between one's present state and desired state. Economic inequality creates such a disparity. In two experiments, we examined whether imposed economic inequality affects risk-taking. In Experiment 1, we examined whether victims of inequality engaged in greater risk-taking compared to beneficiaries of inequality and those not experiencing inequality. In Experiment 2, we examined whether ameliorating inequality for victims reduced risk-taking. In both experiments, victims of inequality engaged in greater risk-taking compared to beneficiaries of inequality and those not experiencing inequality. Among victims, amelioration of inequality contributed to decreased risk-taking. These findings provide further evidence in support of risk-sensitivity theory and suggest that reductions in economic inequality may lead to lower risk-taking.

Probability judgments under ambiguity and conflict

Whether conflict and ambiguity are distinct kinds of uncertainty remains an open question, as does their joint impact on judgments of overall uncertainty. This paper reviews recent advances in our understanding of human judgment and decision making when both ambiguity and conflict are present, and presents two types of testable models of judgments under conflict and ambiguity. The first type concerns estimate-pooling to arrive at “best” probability estimates. The second type is models of subjective assessments of conflict and ambiguity. These models are developed for dealing with both described and experienced information. A framework for testing these models in the described-information setting is presented, including a reanalysis of a multi-nation data-set to test best-estimate models, and a study of participants' assessments of conflict, ambiguity, and overall uncertainty reported by Smithson (2013). A framework for research in the experienced-information setting is then developed, that differs substantially from extant paradigms in the literature. This framework yields new models of “best” estimates and perceived conflict. The paper concludes with specific suggestions for future research on judgment and decision making under conflict and ambiguity.

Relative gains, losses, and reference points in probabilistic choice in rats

Theoretical reference points have been proposed to differentiate probabilistic gains from probabilistic losses in humans, but such a phenomenon in non-human animals has yet to be thoroughly elucidated. Three experiments evaluated the effect of reward magnitude on probabilistic choice in rats, seeking to determine reference point use by examining the effect of previous outcome magnitude(s) on subsequent choice behavior. Rats were trained to choose between an outcome that always delivered reward (low-uncertainty choice) and one that probabilistically delivered reward (high-uncertainty). The probability of high-uncertainty outcome receipt and the magnitudes of low-uncertainty and high-uncertainty outcomes were manipulated within and between experiments. Both the low- and high-uncertainty outcomes involved variable reward magnitudes, so that either a smaller or larger magnitude was probabilistically delivered, as well as reward omission following high-uncertainty choices. In Experiments 1 and 2, the between groups factor was the magnitude of the high-uncertainty-smaller (H-S) and high-uncertainty-larger (H-L) outcome, respectively. The H-S magnitude manipulation differentiated the groups, while the H-L magnitude manipulation did not. Experiment 3 showed that manipulating the probability of differential losses as well as the expected value of the low-uncertainty choice produced systematic effects on choice behavior. The results suggest that the reference point for probabilistic gains and losses was the expected value of the low-uncertainty choice. Current theories of probabilistic choice behavior have difficulty accounting for the present results, so an integrated theoretical framework is proposed. Overall, the present results have implications for understanding individual differences and corresponding underlying mechanisms of probabilistic choice behavior.

Brain areas activated by uncertain reward-based decision-making in healthy volunteers

Reward-based decision-making has been found to activate several brain areas, including the ventrolateral prefrontal lobe, orbitofrontal cortex, anterior cingulate cortex, ventral striatum, and mesolimbic dopaminergic system. In this study, we observed brain areas activated under three degrees of uncertainty in a reward-based decision-making task (certain, risky, and ambiguous). The tasks were presented using a brain function audiovisual stimulation system. We conducted brain scans of 15 healthy volunteers using a 3.0T magnetic resonance scanner. We used SPM8 to analyze the location and intensity of activation during the reward-based decision-making task, with respect to the three conditions. We found that the orbitofrontal cortex was activated in the certain reward condition, while the prefrontal cortex, precentral gyrus, occipital visual cortex, inferior parietal lobe, cerebellar posterior lobe, middle temporal gyrus, inferior temporal gyrus, limbic lobe, and midbrain were activated during the ‘risk’ condition. The prefrontal cortex, temporal pole, inferior temporal gyrus, occipital visual cortex, and cerebellar posterior lobe were activated during ambiguous decision-making. The ventrolateral prefrontal lobe, frontal pole of the prefrontal lobe, orbitofrontal cortex, precentral gyrus, inferior temporal gyrus, fusiform gyrus, supramarginal gyrus, inferior parietal lobule, and cerebellar posterior lobe exhibited greater activation in the ‘risk’ than in the ‘certain’ condition (P < 0.05). The frontal pole and dorsolateral region of the prefrontal lobe, as well as the cerebellar posterior lobe, showed significantly greater activation in the ‘ambiguous’ condition compared to the ‘risk’ condition (P < 0.05). The prefrontal lobe, occipital lobe, parietal lobe, temporal lobe, limbic lobe, midbrain, and posterior lobe of the cerebellum were activated during decision-making about uncertain rewards. Thus, we observed different levels and regions of activation for different types of reward processing during decision-making. Specifically, when the degree of reward uncertainty increased, the number of activated brain areas increased, including greater activation of brain areas associated with loss.

Decision-Making Under Risk: Integrating Perspectives From Biology, Economics, and Psychology

Decision-making under risk has been variably characterized and examined in many different disciplines. However, interdisciplinary integration has not been forthcoming. Classic theories of decision-making have not been amply revised in light of greater empirical data on actual patterns of decision-making behavior. Furthermore, the meta-theoretical framework of evolution by natural selection has been largely ignored in theories of decision-making under risk in the human behavioral sciences. In this review, I critically examine four of the most influential theories of decision-making from economics, psychology, and biology: expected utility theory, prospect theory, risk-sensitivity theory, and heuristic approaches. I focus especially on risk-sensitivity theory, which offers a framework for understanding decision-making under risk that explicitly involves evolutionary considerations. I also review robust empirical evidence for individual differences and environmental/situational factors that predict actual risky decision-making that any general theory must account for. Finally, I offer steps toward integrating various theoretical perspectives and empirical findings on risky decision-making.

Differential responses to anticipation of reward after an acute dose of the designer drugs benzylpiperazine (BZP) and trifluoromethylphenylpiperazine (TFMPP) alone and in combination using functional magnetic resonance imaging (fMRI)

RATIONALE

Functional magnetic resonance imaging (fMRI) studies have reported increased activation of the mesolimbic system in response to anticipation of rewarding stimuli. The anticipation of uncertain outcomes evokes activation in the amygdala, orbitofrontal cortex, inferior frontal gyrus and insula. Drugs known to effect dopaminergic and serotonergic neurons also alter regional activation.

OBJECTIVES

Benzylpiperazine (BZP) and/or trifluoromethylphenylpiperazine (TFMPP) have been recreationally used worldwide for more than a decade. BZP affects mainly dopaminergic neurons, while TFMPP has serotonergic effects.

METHODS

We investigated the effects of an acute dose of BZP, TFMPP or a combination of BZP and TFMPP on the anticipation of reward in a double-blind, placebo-controlled, crossover study using fMRI. An event-related gambling paradigm was completed by healthy controls 90 min after taking an oral dose of either BZP (200 mg), TFMPP (either 50 or 60 mg), BZP + TFMPP (100 + 30 mg) or placebo.

RESULTS

After giving BZP, the anticipation of a $4 reward decreased the activation of the inferior frontal gyrus, insula and occipital regions in comparison to placebo. TFMPP increased the activation of the putamen but decreased the activity in the insula relative to placebo. When BZP and TFMPP were given in combination, activation of the rolandic operculum occurred. The magnitude of reward also affected neural correlates.

CONCLUSION

We propose that the effects of BZP and TFMPP on dopaminergic and serotonergic circuitry, respectively, reflect regional changes. The dopaminergic effects of BZP appear to increase positive arousal and subsequently reduce the response to uncertainty, while TFMPP appears to alter the response to uncertainty by increasing emotional responses.

Foraging under conditions of short-term exploitative competition: the case of stock traders

Theory purports that animal foraging choices evolve to maximize returns, such as net energy intake. Empirical research in both human and non-human animals reveals that individuals often attend to the foraging choices of their competitors while making their own foraging choices. Owing to the complications of gathering field data or constructing experiments, however, broad facts relating theoretically optimal and empirically realized foraging choices are only now emerging. Here, we analyse foraging choices of a cohort of professional day traders who must choose between trading the same stock multiple times in a row--patch exploitation--or switching to a different stock--patch exploration--with potentially higher returns. We measure the difference between a trader's resource intake and the competitors' expected intake within a short period of time--a difference we call short-term comparative returns. We find that traders' choices can be explained by foraging heuristics that maximize their daily short-term comparative returns. However, we find no one-best relationship between different trading choices and net income intake. This suggests that traders' choices can be short-term win oriented and, paradoxically, maybe maladaptive for absolute market returns.

The role of risk aversion in non-conscious decision making

To what extent can people choose advantageously without knowing why they are making those choices? This hotly debated question has capitalized on the Iowa Gambling Task (IGT), in which people often learn to choose advantageously without appearing to know why. However, because the IGT is unconstrained in many respects, this finding remains debated and other interpretations are possible (e.g., risk aversion, ambiguity aversion, limits of working memory, or insensitivity to reward/punishment can explain the finding of the IGT). Here we devised an improved variant of the IGT in which the deck-payoff contingency switches after subjects repeatedly choose from a good deck, offering the statistical power of repeated within-subject measures based on learning the reward contingencies associated with each deck. We found that participants exhibited low confidence in their choices, as probed with post-decision wagering, despite high accuracy in selecting advantageous decks in the task, which is putative evidence for non-conscious decision making. However, such a behavioral dissociation could also be explained by risk aversion, a tendency to avoid risky decisions under uncertainty. By explicitly measuring risk aversion for each individual, we predicted subjects’ post-decision wagering using Bayesian modeling. We found that risk aversion indeed does play a role, but that it did not explain the entire effect. Moreover, independently measured risk aversion was uncorrelated with risk aversion exhibited during our version of the IGT, raising the possibility that the latter risk aversion may be non-conscious. Our findings support the idea that people can make optimal choices without being fully aware of the basis of their decision. We suggest that non-conscious decision making may be mediated by emotional feelings of risk that are based on mechanisms distinct from those that support cognitive assessment of risk.

Decision-making under uncertainty: biases and Bayesians

Animals (including humans) often face circumstances in which the best choice of action is not certain. Environmental cues may be ambiguous, and choices may be risky. This paper reviews the theoretical side of decision-making under uncertainty, particularly with regard to unknown risk (ambiguity). We use simple models to show that, irrespective of pay-offs, whether it is optimal to bias probability estimates depends upon how those estimates have been generated. In particular, if estimates have been calculated in a Bayesian framework with a sensible prior, it is best to use unbiased estimates. We review the extent of evidence for and against viewing animals (including humans) as Bayesian decision-makers. We pay particular attention to the Ellsberg Paradox, a classic result from experimental economics, in which human subjects appear to deviate from optimal decision-making by demonstrating an apparent aversion to ambiguity in a choice between two options with equal expected rewards. The paradox initially seems to be an example where decision-making estimates are biased relative to the Bayesian optimum. We discuss the extent to which the Bayesian paradigm might be applied to the evolution of decision-makers and how the Ellsberg Paradox may, with a deeper understanding, be resolved.

Alterations in choice behavior by manipulations of world model

How to compute initially unknown reward values makes up one of the key problems in reinforcement learning theory, with two basic approaches being used. Model-free algorithms rely on the accumulation of substantial amounts of experience to compute the value of actions, whereas in model-based learning, the agent seeks to learn the generative process for outcomes from which the value of actions can be predicted. Here we show that (i) "probability matching"-a consistent example of suboptimal choice behavior seen in humans-occurs in an optimal Bayesian model-based learner using a max decision rule that is initialized with ecologically plausible, but incorrect beliefs about the generative process for outcomes and (ii) human behavior can be strongly and predictably altered by the presence of cues suggestive of various generative processes, despite statistically identical outcome generation. These results suggest human decision making is rational and model based and not consistent with model-free learning.

Colloquium paper: adaptive specializations, social exchange, and the evolution of human intelligence

Blank-slate theories of human intelligence propose that reasoning is carried out by general-purpose operations applied uniformly across contents. An evolutionary approach implies a radically different model of human intelligence. The task demands of different adaptive problems select for functionally specialized problem-solving strategies, unleashing massive increases in problem-solving power for ancestrally recurrent adaptive problems. Because exchange can evolve only if cooperators can detect cheaters, we hypothesized that the human mind would be equipped with a neurocognitive system specialized for reasoning about social exchange. Whereas humans perform poorly when asked to detect violations of most conditional rules, we predicted and found a dramatic spike in performance when the rule specifies an exchange and violations correspond to cheating. According to critics, people's uncanny accuracy at detecting violations of social exchange rules does not reflect a cheater detection mechanism, but extends instead to all rules regulating when actions are permitted (deontic conditionals). Here we report experimental tests that falsify these theories by demonstrating that deontic rules as a class do not elicit the search for violations. We show that the cheater detection system functions with pinpoint accuracy, searching for violations of social exchange rules only when these are likely to reveal the presence of someone who intends to cheat. It does not search for violations of social exchange rules when these are accidental, when they do not benefit the violator, or when the situation would make cheating difficult.

An effect of inter-trial duration on the gambler's fallacy choice bias

The gambler's fallacy is defined as the avoidance of a winning outcome in a stochastic environment with a constant probability. We tested the possibility that the gambler's fallacy in humans is responsive to the amount of time between choice allocations. Two groups of subjects were placed in a six-choice betting game in which the choices were clustered into two "patches." Groups were defined by the length of time - 2s or 6s - between trials. On any given trial subjects allocated six points among the alternatives, and retained any points that were bet on the winning alternative. Both groups showed evidence of the gambler's fallacy bias. However, the bias was stronger in the 6-s ITI group than in the 2-s ITI group. This difference was found primarily to be due to differences in the number of subjects showing an opposing bias to the gambler's fallacy, namely a preference for the most recent winning alternative. This choice bias is termed the hot hand fallacy. Our findings contradict predictions derived from a foraging heuristic and from traditional accounts of the gambler's fallacy.

Laypersons' responses to the communication of uncertainty regarding cancer risk estimates

OBJECTIVE

To explore laypersons' responses to the communication of uncertainty associated with individualized cancer risk estimates and to identify reasons for individual differences in these responses.

DESIGN

A qualitative study was conducted using focus groups. Participants were informed about a new colorectal cancer risk prediction model, and presented with hypothetical individualized risk estimates using presentation formats varying in expressed uncertainty (range v. point estimate). Semistructured interviews explored participants' responses to this information.

PARTICIPANTS AND SETTING

Eight focus groups were conducted with 48 adults aged 50 to 74 residing in 2 major US metropolitan areas, Chicago, IL and Washington, DC. Purposive sampling was used to recruit participants with a high school or greater education, some familiarity with information technology, and no personal or immediate family history of cancer.

RESULTS

Participants identified several sources of uncertainty regarding cancer risk estimates, including missing data, limitations in accuracy and source credibility, and conflicting information. In comparing presentation formats, most participants reported greater worry and perceived risk with the range than with the point estimate, consistent with the phenomenon of "ambiguity aversion.'' However, others reported the opposite effect or else indifference between formats. Reasons suggested by participants' responses included individual differences in optimism and motivations to reduce feelings of vulnerability and personal lack of control. Perceptions of source credibility and risk mutability emerged as potential mediating factors.

CONCLUSIONS

Laypersons' responses to the communication of uncertainty regarding cancer risk estimates differ, and include both heightened and diminished risk perceptions. These differences may be attributable to personality, cognitive, and motivational factors.