The risky choice framing effect disclosed that presenting data in a loss scenario lead decision-makers towards risky choices. Conversely, a gain scenario prevents them from taking a risk. Framing effect robustness has been widely confirmed by psychological literature. However, the framing of medical treatments, based on McNeil et al. (1982) paradigm, raised both methodological doubts and contrasting evidence. Our research aimed to investigate the presence and the nature of the framing effect in the McNeil et al. (1982) paradigm. In particular, we thought that the obtained switch of preferences across frames was due to a misleading formulation of the data given in a negative cumulative frequency format. We conducted three studies: (1) we replicated McNeil et al.’s (1982) original study (N=150) with medicine (n=50), statistics (n=50) and lay (n=50) students; (2) we tested (N=180) our hypothesis by comparing a cumulative frequency format with an alternative version, namely a linear progression one; (3) we compared (N=430) the effect of different formats (cumulative frequency, linear progression and interval frequency) on choices. Our results showed that, while the framing effect is present when employing a cumulative frequency format, it disappears when using a linear progression one. Moreover, our results show that decision-makers better understand information when given in a linear progression and an interval frequency format. In the current paper, we argue that the way in which a problem is formulated plays a relevant role in the representation of the decisional task and the decision-making.

Mathematical and computational decision models are powerful tools for studyingchoice behavior, and hundreds of distinct decision models have been proposedover the long interdisciplinary history of decision making research. Theexistence of so many models has led to theoretical fragmentation and redundancy,obscuring key insights into choice behavior, and preventing consensus about theessential properties of preferential choice. We provide a synthesis of formalmodels of risky, multiattribute, and intertemporal choice, three importantdomains in decision making. We identify recurring insights discovered byscholars of different generations and different disciplines across these threedomains, and use these insights to classify over 150 existing models asinvolving various combinations of eight key mathematical and computationalproperties. These properties capture the main avenues of theoretical developmentin decision making research and can be used to understand the similarities anddifferences between decision models, aiding both theoretical analyses andempirical tests.

In ten studies (N = 9187), I systematically investigated the direction and sizeof seven helping effects (the identifiable-victim effect, proportion dominanceeffect, ingroup effect, existence effect, innocence effect, age effect andgender effect). All effects were tested in three decision modes (separateevaluation, joint evaluation and forced choice), and in their weak form (equalefficiency), or strong form (unequal efficiency). Participants read about one,or two, medical help projects and rated the attractiveness of and allocatedresources to the project/projects, or choose which project to implement. Theresults show that the included help-situation attributes vary in their: (1)Evaluability – e.g., rescue proportion is the easiest to evaluate inseparate evaluation. (2) Justifiability – e.g., people prefer to savefewer lives now rather than more lives in the future, but not fewer identifiedlives rather than more statistical lives. (3) Prominence – e.g., peopleexpress a preference to help females, but only when forced to choose.

Harmful acts are punished more often and more harshly than harmful omissions. This asymmetry has variously been ascribed to differences in how individuals perceive the causal responsibility of acts versus omissions and to social norms that tend to proscribe acts more frequently than omissions. This paper examines both of these hypotheses, in conjunction with a new hypothesis: that acts are punished more than omissions because it is usually more efficient to do so. In typical settings, harms occur as a result of relatively few harmful actions, but many individuals may have had the opportunity to prevent or rectify the harm. Penalising actors therefore requires relatively few punishment events compared to punishing omitters. We employ a novel group paradigm in which harm occurs only if both actors and omitters contribute to the harm. Subjects play a repeated economic game in fixed groups involving a social dilemma (total N = 580): on each round self-interest favours harmful actions (taking from another) and harmful omissions (failing to repair the victim’s loss), but the group payoff is maximized if individuals refrain from these behaviors. In one treatment harm occurs as a result of one action and two omissions; in the other, it is the result of two actions and one omission. In the second treatment, the more efficient strategy to maximize group benefit is to punish omissions. We find that subjects continue to prefer to punish acts rather than omissions, with two important caveats. There is still a substantial level of punishment of omissions, and there is also evidence of some responsiveness to the opportunity to enforce a more efficient rule. Further analysis addresses whether the omission effect is associated with asymmetric norm-based attitudes: a substantial proportion of subjects regard it as equally fair to punish harmful acts and omissions, while another portion endorse an asymmetry; and punishment behavior correlates with these attitudes in both groups.

In many situations people behave ethically, while elsewhere dishonesty reigns. Studies of the determinants of unethical behavior often use random assignment of participants in various conditions to identify contextual or psychological factors influencing dishonesty. However, in many real-world contexts, people deliberately choose or avoid specific environments. In three experiments (total N = 2,124) enabling self-selection of participants in two similar tasks, one of which allowed for cheating, we found that participants who chose the task where they could lie for financial gain reported a higher number of correct predictions than those who were assigned it at random. Introduction of financial costs for entering the cheating-allowing task led to a decrease in interest in the task; however, it also led to more intense cheating. An intervention aimed to discourage participants from choosing the cheating-enabling environment based on social norm information did not have the expected effect; on the contrary, it backfired. In summary, the results suggest that people low in moral character are likely to eventually dominate cheating-enabling environments, where they then cheat extensively. Interventions trying to limit the preference of this environment may not have the expected effect as they could lead to the selection of the worst fraudsters.

The COVID-19 crisis has forced healthcare professionals to make tragic decisions concerning which patients to save. Furthermore, The COVID-19 crisis has foregrounded the influence of self-serving bias in debates on how to allocate scarce resources. A utilitarian principle favors allocating scarce resources such as ventilators toward younger patients, as this is expected to save more years of life. Some view this as ageist, instead favoring age-neutral principles, such as “first come, first served”. Which approach is fairer? The “veil of ignorance” is a moral reasoning device designed to promote impartial decision-making by reducing decision-makers’ use of potentially biasing information about who will benefit most or least from the available options. Veil-of-ignorance reasoning was originally applied by philosophers and economists to foundational questions concerning the overall organization of society. Here we apply veil-of-ignorance reasoning to the COVID-19 ventilator dilemma, asking participants which policy they would prefer if they did not know whether they were younger or older. Two studies (pre-registered; online samples; Study 1, N=414; Study 2 replication, N=1,276) show that veil-of-ignorance reasoning shifts preferences toward saving younger patients. The effect on older participants is dramatic, reversing their opposition toward favoring the young, thereby eliminating self-serving bias. These findings provide guidance on how to remove self-serving biases to healthcare policymakers and frontline personnel charged with allocating scarce medical resources during times of crisis.

Recent research has highlighted a tendency for more rational and deliberative decision-making in individuals with autism. We tested this hypothesis by using eye-tracking to investigate the information processing strategies that underpin multi-attribute choice in a sample of adults diagnosed with autism spectrum condition. We found that, as the number of attributes defining each option increased, autistic decision-makers were speedier, examined less of the available information, and spent a greater proportion of their time examining the option they eventually chose. Rather than indicating a more deliberative style, our results are consistent with a tendency for individuals with autism to narrow down the decision-space more quickly than does the neurotypical population.

This paper illustrates how to apply the RECIPE design to evaluate multiattributejudgment, reporting an experiment in which participants judged intentions toreceive a new vaccine against COVID-19. The attributes varied were Price of thevaccine, Risks of side effects as reported in trials, and Effectiveness of thevaccine in preventing COVID. The RECIPE design is a union of factorial designsin which each of three attributes is presented alone, in pairs with each of theother attributes, and in a complete factorial with all other information.Consistent with previous research with analogous judgment tasks, the additiveand relative weight averaging models with constant weights could be rejected infavor of a configural weight averaging model in which the lowest-valuedattribute receives additional weight. That is, people are unlikely to acceptvaccination if Price is too high, Risk is too high, or Effectiveness is too low.The attribute with the greatest weight was Effectiveness, followed by Risk ofside-effects, and Price carried the least weight.

We study whether experts and novices differ in the way they make predictionsabout National Football League games. In particular, we measure to what extenttheir predictions are consistent with five environmental regularities that couldsupport decision making based on heuristics. These regularities involve the hometeam winning more often, the team with the better win-loss record winning moreoften, the team favored by the majority of media experts winning more often, andtwo others related to surprise wins and losses in the teams’ previousgame. Using signal detection theory and hierarchical Bayesian analysis, we showthat expert predictions for the 2017 National Football League (NFL) seasongenerally follow these regularities in a near optimal way, but novicepredictions do not. These results support the idea that using heuristics adaptedto the decision environment can support accurate predictions and be an indicatorof expertise.

Research on small repeated decisions from experience suggests that people often behave as if they underweight rare events and choose the options that are frequently better. In a pandemic, this tendency implies complacency and reckless behavior. Furthermore, behavioral contagion exacerbates this problem. In two pre-registered experiments (Ntotal = 312), we validate these predictions and highlight a potential solution. Groups of participants played a repeated game in one of two versions. In the basic version, people clearly preferred the dangerous reckless behavior that was better most of the time over the safer responsible behavior. In the augmented version, we gave participants an additional alternative abstracting the use of an application that frequently saves time but can sometimes have high costs. This alternative was stochastically dominated by the responsible choice option and was thus normatively irrelevant to the decision participants made. Nevertheless, most participants chose the new (“irrelevant”) alternative, providing the first clear demonstration of underweighting of rare events in fully described social games. We discuss public policies that can make the responsible use of health applications better most of the time, thus helping them get traction despite being voluntary. In one field demonstration of this idea amid the COVID-19 pandemic, usage rates of a contact tracing application among nursing home employees more than tripled when using the app also started saving them a little time each day, and the high usage rates sustained over at least four weeks.

In 2020, most countries around the world adopted various measures aimed at combating the coronavirus (i.e., COVID-19), or reducing risky behavior which may spread the virus. In the current study (N = 215), we examined compliance with COVID-19 prevention guidelines using a risk-taking perspective, differentiating active from passive risk taking. In the corona context active risk taking involves actions that may cause disease contraction, such as shaking hands, while passive risk taking involves the acceptance of risk brought on by inaction, as in not using an alco-gel disinfectant. We found that personal tendencies for passive and active risk taking predicted passive and active corona related risk taking, respectively. Furthermore, compliance with COVID-19 prevention measures was also related to differences in self-control, with low Initiation self-control predicting passive corona risk taking and low levels of Inhibition self-control predicting active corona risk taking. Thus, while not complying with Covid-19 prevention measures put people at risk, differentiating between active and passive risks is helpful for accurate prediction of each type of risk behavior.

Online experiments have become a valuable research tool for researchers interested in the processes underlying cooperation. Typically, online experiments are asynchronous, participants complete an experiment individually and are matched with partners after data collection has been completed. We conducted a registered report to compare asynchronous and synchronous designs, where participants interact and receive feedback in real-time. We investigated how two features of synchronous designs, pre-decision matching and immediate feedback, influence cooperation in the prisoners dilemma. We hypothesized that 1) pre-decision matching (assigning participants to specific interaction partners before they make decisions) would lead to decreased social distance and increased cooperation; 2) immediate feedback would reduce feelings of aversive uncertainty and lead to increased cooperation; and 3) individuals with prosocial Social Value Orientations would be more sensitive to the differences between synchronous and asynchronous designs. We found no support for these hypotheses. In our study (N = 1,238), pre-decision matching and immediate feedback had no significant effects on cooperative behavior or perceptions of the interaction; and their effects on cooperation were not significantly moderated by Social Value Orientation. The present results suggest that synchronous designs have little effect on cooperation in online social dilemma experiments.

We conducted a replication of Shafir (1993) who showed that people are inconsistent in their preferences when faced with choosing versus rejecting decision-making scenarios. The effect was demonstrated using an enrichment paradigm, asking subjects to choose between enriched and impoverished alternatives, with enriched alternatives having more positive and negative features than the impoverished alternative. Using eight different decision scenarios, Shafir found support for a compatibility principle: subjects chose and rejected enriched alternatives in choose and reject decision scenarios (d = 0.32 [0.23,0.40]), respectively, and indicated greater preference for the enriched alternative in the choice task than in the rejection task (d = 0.38 [0.29,0.46]). In a preregistered very close replication of the original study (N = 1026), we found no consistent support for the hypotheses across the eight problems: two had similar effects, two had opposite effects, and four showed no effects (overall d = −0.01 [−0.06,0.03]). Seeking alternative explanations, we tested an extension, and found support for the accentuation hypothesis.

Previous research in multiple judgment domains has found that nonlinear functionsare typically processed less accurately than linear ones. This empiricalregularity has potential implications for consumer choice, given that nonlinearfunctions (e.g., diminishing returns) are commonplace. In two experimentalstudies we measured precision and bias in consumers’ ability to identifysurpluses when returns to product attributes were nonlinear. We hypothesizedthat nonlinear functions would reduce precision and induce bias towardlinearization of nonlinear relationships. Neither hypothesis was supported formonotonic nonlinearities. However, precision was greatly reduced for productswith nonmonotonic attributes. Moreover, assessments of surplus weresystematically and strongly biased, regardless of the shape of returns anddespite feedback and incentives. The findings imply that consumers use aflexible but coarse mechanism to compare attributes against prices, withimplications for the prevalence of costly mistakes.

As a complement to high-cost cooperation as assessed in economic games, the concept of social mindfulness focuses on low-cost acts of kindness. While social mindfulness seems quite natural, performed by many most of the time (reaching a level of 60–70 percent), what happens if such acts become more costly, and if costs become more salient? The present research replicates the prevalence of social mindfulness when costs are salient, but low. Yet we show that, with small increments in costs, the vast majority no longer exhibits social mindfulness. This holds even if we keep the outcomes for self high in comparison with the beneficiary. We conclude that the literature on social mindfulness should pay attention to cost. Clearly, if being socially mindful comes with high costs, this is not what most people are prepared to do. In contrast as long as costs are low and not salient, social mindfulness seems natural and normative.

People are more likely to endorse statements of the form "A is more than B" than those of the form "B is less than A", even though the ordinal relationship being described is identical in both cases -– a result I dub the "more-credible" effect. This paper reports 9 experiments (total N = 5643) that probe the generality and basis for this effect. Studies 1–4 replicate the effect for comparative statements relating to environmental change and sustainable behaviours, finding that it is robust to changes in participant population, experimental design, response formats and data analysis strategy. However, it does not generalize to all stimulus sets. Studies 5–9 test the proposition that the effect is based on the greater ease of processing "more than" statements. I find no meaningful effect of warning people not to base their judgments on the fluency of the sentences (Studies 5 and 6), but do find associations between comparative language, credibility, and processing time: when the more-credible effect manifests, the more-than statements are read more quickly than the less-than statements, and this difference partly mediates the effect of comparative on agreement with the statements; in contrast, for a set of comparisons for which changes in the more/less framing did not affect truth judgments, there was no meaningful difference in the time taken to read the more- and less-than versions of the statements. Taken together, these results highlight the importance of comparative language in shaping the credibility of important socio-political messages, and provide some limited support for the idea that the effect of language choice is partly due to differences in how easily the statements can be processed -– although other mechanisms are also likely to be at work.

This paper introduces the Hierarchical Mindreading Model (HMM), a new model of mindreading in two-person, mixed-motive games such as the Prisoners’ Dilemma. The HMM proposes that the strategies available to decision makers in these games can be classified on a hierarchy according to the type of mindreading involved. At Level 0 of the HMM, there is no attempt to infer the intentions of the other player from any of the context-specific information (i.e., signals, payoffs, or partner reliability). At Level 1, decision makers rely on signals to infer the other’s intention, without considering the possibility that those signals might not reflect the other’s true intention. Finally, in Level 2 strategies, decision makers infer the other player’s intended choice by integrating information contained in their signals with the apparent reliability of the other participant and/or the game’s payoffs. The implications of the HMM were tested across four studies involving 962 participants, with results consistently indicating the presence of strategies from all three levels of the HMM’s hierarchy.

Bias Blind Spot (BBS) is the phenomenon that people tend to perceive themselvesas less susceptible to biases than others. In three pre-registered experiments(overall N = 969), we replicated two experiments of the first demonstration ofthe phenomenon by Pronin et al. (2002). We found support of the BBS hypotheses,with effects in line with findings in the original study: Participants ratedthemselves as less susceptible to biases than others (d =–1.00 [–1.33, –0.67]). Deviating from the original, wefound an unexpected effect that participants rated themselves as having fewershortcomings (d = –0.34 [–0.46, –0.23]),though there was support for the target’s main premise that BBS wasstronger for biases than for shortcomings (d = –0.43[–0.56, –0.29]). Extending the replications, we found that beliefsin own free will were positively associated with BBS (r ∼0.17–0.22) and that beliefs in both own and general free will werepositively associated with self-other asymmetry related to personal shortcomings(r ∼ 0.16–0.24). Materials, datasets, andcode are available on https://osf.io/3df5s/.

Interrupted time-series graphs are often judged by eye. Such a graph might show, for example, patient symptom severity (y) on each of several days (x) before and after a treatment was implemented (interruption). Such graphs might be prone to systematic misjudgment because of serial dependence, where random error at each timepoint persists into later timepoints. An earlier study (Matyas & Greenwood, 1990) showed evidence of systematic misjudgment, but that study has often been discounted due to methodological concerns. We address these concerns and others in two experiments. In both experiments, serial dependence increased mistaken judgments that the interrupting event led to a change in the outcome, though the pattern of results was less extreme than in previous work. Receiver operating characteristics suggested that serial dependence both decreased discriminability and increased the bias to decide that the interrupting event led to a change. This serial dependence effect appeared despite financial incentives for accuracy, despite feedback training, and even in participants who had graduate training relevant to the task. Serial dependence could cause random error to be misattributed to real change, thereby leading to judgments that interventions are effective even when they are not.

Recent work has derived the optimal policy for two-alternative value-baseddecisions, in which decision-makers compare the subjective expected reward oftwo alternatives. Under specific task assumptions — such as linearutility, linear cost of time and constant processing noise — the optimalpolicy is implemented by a diffusion process in which parallel decisionthresholds collapse over time as a function of prior knowledge about averagereward across trials. This policy predicts that the decision dynamics of eachtrial are dominated by the difference in value between alternatives and areinsensitive to the magnitude of the alternatives (i.e., their summed values).This prediction clashes with empirical evidence showing magnitude-sensitivityeven in the case of equal alternatives, and with ecologically plausible accountsof decision making. Previous work has shown that relaxing assumptions aboutlinear utility or linear time cost can give rise to optimal magnitude-sensitivepolicies. Here we question the assumption of constant processing noise, infavour of input-dependent noise. The neurally plausible assumption ofinput-dependent noise during evidence accumulation has received strong supportfrom previous experimental and modelling work. We show that includinginput-dependent noise in the evidence accumulation process results in amagnitude-sensitive optimal policy for value-based decision-making, even in thecase of a linear utility function and a linear cost of time, for both single(i.e., isolated) choices and sequences of choices in which decision-makersmaximise reward rate. Compared to explanations that rely on non-linear utilityfunctions and/or non-linear cost of time, our proposed account ofmagnitude-sensitive optimal decision-making provides a parsimonious explanationthat bridges the gap between various task assumptions and between various typesof decision making.