A synthesis of evidence for policy from behavioural science during COVID-19.

Scientific evidence regularly guides policy decisions1, with behavioural science increasingly part of this process2. In April 2020, an influential paper3 proposed 19 policy recommendations ('claims') detailing how evidence from behavioural science could contribute to efforts to reduce impacts and end the COVID-19 pandemic. Here we assess 747 pandemic-related research articles that empirically investigated those claims. We report the scale of evidence and whether evidence supports them to indicate applicability for policymaking. Two independent teams, involving 72 reviewers, found evidence for 18 of 19 claims, with both teams finding evidence supporting 16 (89%) of those 18 claims. The strongest evidence supported claims that anticipated culture, polarization and misinformation would be associated with policy effectiveness. Claims suggesting trusted leaders and positive social norms increased adherence to behavioural interventions also had strong empirical support, as did appealing to social consensus or bipartisan agreement. Targeted language in messaging yielded mixed effects and there were no effects for highlighting individual benefits or protecting others. No available evidence existed to assess any distinct differences in effects between using the terms 'physical distancing' and 'social distancing'. Analysis of 463 papers containing data showed generally large samples; 418 involved human participants with a mean of 16,848 (median of 1,699). That statistical power underscored improved suitability of behavioural science research for informing policy decisions. Furthermore, by implementing a standardized approach to evidence selection and synthesis, we amplify broader implications for advancing scientific evidence in policy formulation and prioritization.

Why are people antiscience, and what can we do about it?

From vaccination refusal to climate change denial, antiscience views are threatening humanity. When different individuals are provided with the same piece of scientific evidence, why do some accept whereas others dismiss it? Building on various emerging data and models that have explored the psychology of being antiscience, we specify four core bases of key principles driving antiscience attitudes. These principles are grounded in decades of research on attitudes, persuasion, social influence, social identity, and information processing. They apply across diverse domains of antiscience phenomena. Specifically, antiscience attitudes are more likely to emerge when a scientific message comes from sources perceived as lacking credibility; when the recipients embrace the social membership or identity of groups with antiscience attitudes; when the scientific message itself contradicts what recipients consider true, favorable, valuable, or moral; or when there is a mismatch between the delivery of the scientific message and the epistemic style of the recipient. Politics triggers or amplifies many principles across all four bases, making it a particularly potent force in antiscience attitudes. Guided by the key principles, we describe evidence-based counteractive strategies for increasing public acceptance of science.

How research on persuasion can inform dual-process models of judgment.

De Neys makes some useful points regarding dual-process models, but his critique ignores highly relevant theories of judgment from the persuasion literature. These persuasion models predate and often circumvent many of the criticisms he makes of the dual-process approaches he covers. Furthermore, the persuasion models anticipated some of the correctives to dual-process models that he proposes.

The impact of grounded procedures can vary as a function of perceived thought validity, meaning, and timing.

Cleansing (separation) inductions reduce the impact of negative and positive reactions, whereas connection manipulations magnify them. We suggest that grounded procedures can produce these effects by affecting the perceived validity of thoughts. In accord with the self-validation theory, we also note the importance of considering how moderators, such as the meaning of the action and the timing of inductions, affect outcomes.

A Validity-Based Framework for Understanding Replication in Psychology.

In recent years, psychology has wrestled with the broader implications of disappointing rates of replication of previously demonstrated effects. This article proposes that many aspects of this pattern of results can be understood within the classic framework of four proposed forms of validity: statistical conclusion validity, internal validity, construct validity, and external validity. The article explains the conceptual logic for how differences in each type of validity across an original study and a subsequent replication attempt can lead to replication "failure." Existing themes in the replication literature related to each type of validity are also highlighted. Furthermore, empirical evidence is considered for the role of each type of validity in non-replication. The article concludes with a discussion of broader implications of this classic validity framework for improving replication rates in psychological research.

Challenging Moral Attitudes With Moral Messages.

When crafting a message, communicators may turn to moral rhetoric as a means of influencing an audience's opinion. In the present research, we tested whether the persuasiveness of explicitly moral counterattitudinal messages depends on how much people have already based their attitudes on moral considerations. A survey of the literature suggests several competing hypotheses that we tested across two studies. The results support a persuasive-matching pattern: A moral appeal was more persuasive than a nonmoral appeal to the extent that initial attitudes were based on moral concerns (i.e., attitudes were moralized), but the opposite was true when initial attitudes had less of a moral basis. Exploratory analyses also showed that these effects were mediated by valenced thoughts about the message and moderated by political orientation. These findings add new insight to literatures on both the effects of moral arguments and moralized attitudes.

Trait aggressiveness predicting aggressive behavior: The moderating role of meta-cognitive certainty.

Research on aggression has benefitted from using individual-difference measures to predict aggressive behavior. Research on meta-cognition has recently identified that the predictive utility of individual-difference inventories can be improved by considering the certainty with which people hold their self-views. Merging these two frameworks, the present research examines whether assessing certainty in trait aggressiveness improves its ability to predict aggressive outcomes. Across two studies, participants reported their level of trait physical aggressiveness and the certainty with which they held their responses to the scale (predictor variables). Aggressive behavioral intentions (Study 1 and 2) and actual aggressive behavior (Study 2) were used as dependent measures. As hypothesized, results indicated that certainty moderated the effects of individual-differences in aggressiveness on both aggressive outcomes. Therefore, considering the certainty with which people hold their relevant traits can be useful for understanding aggression, and also for predicting the consistency between personality and behavior.

The Effects of Overt Head Movements on Physical Performance After Positive Versus Negative Self-Talk.

Research on self-talk has found that what athletes say to themselves influences their performance in sport settings. This experiment analyzed the relationship between positive and negative self-talk and physical performance in light of another variable: overt head movements. Participants were randomly assigned to first generate and then listen to either positive or negative self-statements. They were then randomly assigned to nod (up and down) or to shake (side to side) their heads while being exposed to the self-statements they had previously generated. Finally, physical performance was assessed using a vertical-jump task, a squat test, and a deadlift task. As expected, positive self-statements led to better performance than negative self-statements in 2 out of 3 physical tasks. Most relevant, the main effect of self-talk was significantly qualified by head movements. Consistent with the authors' hypothesis, athletes' self-statements were significantly more impactful on physical performance in the head-nodding condition than in the head-shaking condition.

The importance of exact conceptual replications.

Although Zwaan et al. argue that original researchers should provide a replication recipe that provides great specificity about the operational details of one's study, I argue that it may be as important to provide a recipe that allows replicators to conduct a study that matches the original in as many conceptual details as possible (i.e., an exact conceptual replication).

From Power to Inaction.

Research has shown that people who feel powerful are more likely to act than those who feel powerless, whereas people who feel ambivalent are less likely to act than those whose reactions are univalent (entirely positive or entirely negative). But what happens when powerful people also are ambivalent? On the basis of the self-validation theory of judgment, we hypothesized that power and ambivalence would interact to predict individuals' action. Because power can validate individuals' reactions, we reasoned that feeling powerful strengthens whatever reactions people have during a decision. It can strengthen univalent reactions and increase action orientation, as shown in past research. Among people who hold an ambivalent judgment, however, those who feel powerful would be less action oriented than those who feel powerless. Two experiments provide evidence for this hypothesized interactive effect of power and ambivalence on individuals' action tendencies during both positive decisions (promoting an employee; Experiment 1) and negative decisions (firing an employee; Experiment 2). In summary, when individuals' reactions are ambivalent, power increases the likelihood of inaction.

Emotion and persuasion: cognitive and meta-cognitive processes impact attitudes.

This article addresses the multiple ways in which emotions can influence attitudes and persuasion via primary and secondary (meta-) cognition. Using the elaboration likelihood model of persuasion as a guide, we review evidence for five fundamental processes that occur at different points along the elaboration continuum. When the extent of thinking is constrained to be low, emotions influence attitudes by relatively simple processes that lead them to change in a manner consistent with the valence of the emotion. When thinking is constrained to be high, emotions can serve as arguments in favour of a proposal if they are relevant to the merits of the advocacy or they can bias thinking if the emotion precedes the message. If thinking is high and emotions become salient after thinking, they can lead people to rely or not rely on the thoughts generated either because the emotion leads people to like or dislike their thoughts (affective validation) or feel more confident or doubtful in their thoughts (cognitive validation). When thinking is unconstrained, emotions influence the extent of thinking about the persuasive communication. Although prior theories have addressed one or more of these fundamental processes, no other approach has integrated them into one framework.

Order Matters When Using Two-Sided Messages to Influence Morally Based Attitudes.

Contrary to common beliefs, sometimes downplaying or even undermining one's case can enhance impact, especially for people with strong attitudes. Across four studies (N = 1,548), we demonstrate that the placement of the undermining information within a two-sided message matters. By manipulating message order within a two-sided message, Study 1 showed that the relative effectiveness of two- over one-sided messages for people with a moral attitude primarily occurred when the two-sided message acknowledged the recipient's side at the end rather than at the beginning of the message. Studies 2A/B showed that this effect was associated with positive source perceptions, such that placing the acknowledgment at the end results in people with a higher moral basis perceiving the source as more thoughtful and sincere. Furthermore, this inference process was more likely to occur when motivation to think was relatively high. Study 3, a preregistered experiment, replicated these findings using a different topic.

Ambivalent attitudes promote support for extreme political actions.

Political extremism varies across people and contexts, but which beliefs will a person support through extreme actions? We propose that ambivalent attitudes, despite reducing normative political actions like voting, increase support for extreme political actions. We demonstrate this hypothesized reversal using dozens of measures across six studies (N = 13,055). The effect was robust to relevant covariates and numerous methodological variations and was magnified when people's attitudinal or ideological positions were more polarized. It appears to occur because being conflicted about political issues can feel psychologically uncomfortable, making extreme actions more appealing. Notably, this emerged when people thought ambivalence was justified, whereas leading them to consider ambivalence unjustified suppressed the effect, suggesting that ambivalent people are coping with but not necessarily trying to reduce their ambivalence. These results highlight the interplay of affective and cognitive influences in extreme behavior, showing that beliefs people feel justifiably conflicted about can promote extremism.

The association of the persecutory ideation questionnaire with clinically-relevant and other outcomes: the moderating role of confidence.

One of the most used self-administered instruments to assess persecutory delusions is the Persecutory Ideation Questionnaire (PIQ). Individual differences in PIQ scores are important because they predict the severity of symptoms associated with psychosis-related disorders. The current research demonstrates that PIQ is associated with two new outcomes: Satisfaction with life (Studies 1 and 2) and therapy length needed for hospital discharge (Study 2). Most relevant, we introduce meta-cognitive confidence in one's scale responses as a construct capable of improving the predictive validity of the PIQ. Across two studies, participants from the general population (Study 1) and from a clinical sample (Study 2) completed the PIQ and then reported the confidence in their responses. As expected, the PIQ was associated with satisfaction with life in both cases and duration of therapy required to receive hospital discharge for the clinical sample. Most importantly, confidence further moderated the extent to which the PIQ scores were linked with both outcomes, with greater consistency between the PIQ and the dependent measures obtained for those with higher confidence. Therefore, asking a single item about the confidence associated with responses to the PIQ enhances the association of PIQ scores and relevant consequences across domains.

Treating thoughts as material objects can increase or decrease their impact on evaluation.

In Western dualistic culture, it is assumed that thoughts cannot be treated as material objects; however, language is replete with metaphorical analogies suggesting otherwise. In the research reported here, we examined whether objectifying thoughts can influence whether the thoughts are used in subsequent evaluations. In Experiment 1, participants wrote about what they either liked or disliked about their bodies. Then, the paper on which they wrote their thoughts was either ripped up and tossed in the trash or kept and checked for errors. When participants physically discarded a representation of their thoughts, they mentally discarded them as well, using them less in forming judgments than did participants who retained a representation of their thoughts. Experiment 2 replicated this finding and also showed that people relied on their thoughts more when they physically kept them in a safe place-putting their thoughts in their pockets-than when they discarded them. A final study revealed that these effects were stronger when the action was performed physically rather than merely imagined.

Understanding the Magnitude of Hypocrisy in Moral Contradictions: The Role of Surprise at Violating Strong Attitudes.

Although two people could both enact similar forms of hypocrisy, one person might be judged as more hypocritical than the other. The present research advances a novel, theoretical explanation for a paradigmatic instance of this: the increased hypocrisy ascribed to contradicting a morally (vs. nonmorally) based attitude. In contrast to prior explanations, the present research shows that people infer targets holding morally (vs. nonmorally) based attitudes are more difficult to change. Consequently, when people are hypocritical on these stances, it elicits greater surprise, which amplifies the perceived hypocrisy. Through both statistical mediation and experimental moderation, we provide evidence for this process and show how our explanation generalizes to understanding heightened hypocrisy in other contexts, too (i.e., violating nonmoral attitudes held with certainty vs. uncertainty). Altogether, we provide an integrative, theoretical lens for predicting when moral and nonmoral acts of hypocrisy will be perceived as particularly hypocritical.

Self-Validation Theory: Confidence can Increase but also Decrease Performance in Applied Settings.

This article presents self-validation theory (SVT) as a framework predicting when mental contents guide performance. First, we illustrate how confidence can validate people's thoughts (goals, beliefs, identity) increasing and decreasing performance, depending on what thoughts are validated. This first section reviews examples of validation processes in guiding intellectual performance in academic settings, sport performance in athletes, as well as performance on diverse social tasks. SVT specifies moderating conditions for validation processes to operate. Therefore, in the second section of this review, we identify unique and testable moderators for metacognitive processes demonstrating when and for whom validation processes are more likely to occur. A third section calls for future research identifying new validating variables (e.g., preparation, courage) capable of increasing usage of unexplored thoughts relevant to performance (e.g., expectations). This final section examines new domains for validation (e.g., group performance, cheating in performance), discusses to what extent people can use self-validation strategies deliberatively to improve their performance and addresses when performance can be impaired by invalidation (e.g., due to identity threat).

Attitude Strength: What's New?

Attitude strength (what makes attitudes durable and impactful) has become an important topic in the domain of social influence. We review three areas in which the traditional view of attitude strength has been modified or updated since the publication of Petty and Krosnick's 1995 edited book on the topic. First, although it was widely assumed that there were different categories of strength variables (i.e., operative versus meta-cognitive), it may now be better to recognize that each strength property can be measured both structurally and subjectively and that each measure is useful. Second, although scholars assumed that virtually all persuasion techniques would work better on weaker than stronger attitudes, recent research suggests that some techniques might actually work better on stronger than weaker attitudes. Third, although stronger attitudes often guide behavior better than weaker ones, when strength is challenged or weak attitudes are threatening, people can be motivated to act to demonstrate or restore certainty. This can result in weaker attitudes leading to more extreme behavior.

Pitch as a Recipient, Channel, and Context Factor Affecting Thought Reliance and Persuasion.

Three experiments tested how low versus high pitch generated from sources beyond a message communicator can affect reliance on thoughts and influence recipients' attitudes. First, participants wrote positive or negative thoughts about an exam proposal (Experiments 1, 2) or their academic abilities (Experiment 3). Then, pitch from the message recipient (Experiment 1), channel (Experiment 2), or context (Experiment 3) was manipulated to be high or low. Experiment 1 showed that when participants vocally expressed their thoughts using low (vs. high) pitch, thoughts had a greater effect on attitudes toward exams. Experiment 2 revealed low (vs. high) pitch sounds from the keyboard participants used to write their thoughts produced the same effect on thought usage. Experiment 3 demonstrated that thoughts influenced attitudes more when listed while background music was low (vs. high) Pitch can influence attitudes through a meta-cognitive thought reliance process whether emerging from the recipient, channel, or context.

Two-Sided Messages Promote Openness for a Variety of Deeply Entrenched Attitudes.

Prior research showed that people holding attitudes on relatively moral topics became more open to two- rather than one-sided messages as the moral basis of their attitudes increased. Across three studies (N = 963), we extend this finding to relatively non-moral topics by demonstrating that two-sided messages can encourage people with strong attitudes indexed by various non-moral attitude strength measures to be more open to contrary positions. Study 1 demonstrated this for four indicators of attitude strength (e.g., certainty). As the strength of one's attitude increased, two-sided messages increased in relative effectiveness over one-sided communication. This was mediated by perceived appreciation for the speaker acknowledging one's view. Study 2 replicated this finding in a preregistered experiment. Study 3 conceptually replicated and extended it to people holding attitudes based on their political identity. Finally, evidence was obtained supporting perceived appreciation (rather than source evaluation) as the key driver of this interactive effect.