The Tavistock First-Time Parent Study: a pilot randomised controlled feasibility trial of a brief couple-focused perinatal intervention to reduce inter-parental discord.

Numerous studies report that some first-time parents experience a decline in relationship quality and an increase in conflict after the birth of a first baby. Inter-parental discord that is frequent, intense, and poorly resolved increases the likelihood of relationship breakdown and adversely impacts child development. We investigated the feasibility of a brief preventative couple-focused psychotherapeutic intervention in the perinatal period in a general population sample. Sixty couples expecting their first baby were recruited from the Royal Free Hospital, London. Thirty were randomly assigned to treatment (TMT, a newly developed five-session couple-focused intervention), and 30 to usual care (TAU). Outcomes were collected at 28 weeks into pregnancy, 6-8 weeks after birth, and when the baby was 6 months old. The intervention was feasible and acceptable, evidenced by 100% attendance. However, no change in relationship quality or inter-parental discord was detected in either TMT or TAU groups across the transition to parenthood. The intervention did not improve outcomes vs. TAU. Depression assessed by the Hospital Anxiety and Depression Scale increased across the cohort and mood symptoms assessed by the Edinburgh Postnatal Depression Scale decreased in mothers but not fathers. The absence of a decline in relationship quality could reflect sample attributes: couples were older than average UK first-time parents, had high levels of educational qualifications, and low discord. Even in this low-risk sample, only 20 out of 30 TAU couples completed all three assessments, vs. 29 out of 30 TMT couples. Larger-scale RCTs of perinatal couple-focused psychosocial interventions may be hampered by selection effects and attrition. They may benefit from co-design with stakeholders and active control conditions.Trial registration: ISRCTN12258825; 1st May 2020 (retrospectively registered).

Altruism, collective rationality, and extreme self-sacrifice.

Puzzlement about extreme self-sacrifice arises from an unarticulated assumption of psychological egoism, according to which people invariably act in their own self-interests. However, altruism and collective rationality are well established experimentally: people sometimes act to benefit others or in the interests of groups to which they belong. When such social motives are sufficiently strong, extreme self-sacrifice presents no special problem of explanation and does not require out-group threats.

Spontaneous similarity discrimination in the evolution of cooperation.

The similarity discrimination effect occurs when a single gene or gene cluster causes its carriers to display both a variable phenotypic trait and a behavioural predisposition to cooperate preferentially with recognisably similar carriers. We distinguish this from the greenbeard effect, in which cooperation evolves through fixed phenotypic tags and genetically linked cooperative behaviour with others displaying the same tag. Our agent-based simulations show that the evolution of cooperation through similarity discrimination, in contrast to the greenbeard effect, does not depend on population viscosity or other restrictive conditions. Similarity discrimination evolves spontaneously in well mixed populations, not only in the Prisoner's Dilemma game but also across a range of different binary-choice strategic interactions, provided that agents can distinguish reliably between similar and dissimilar co-players.

Does competitive winning increase subsequent cheating?

In this preregistered study, we attempted to replicate and substantially extend a frequently cited experiment by Schurr and Ritov, published in 2016, suggesting that winners of pairwise competitions are more likely than others to steal money in subsequent games of chance against different opponents, possibly because of an enhanced sense of entitlement among competition winners. A replication seemed desirable because of the relevance of the effect to dishonesty in everyday life, the apparent counterintuitivity of the effect, possible problems and anomalies in the original study, and above all the fact that the researchers investigated only one potential explanation for the effect. Our results failed to replicate Schurr and Ritov's basic finding: we found no evidence to support the hypotheses that either winning or losing is associated with subsequent cheating. A second online study also failed to replicate Schurr and Ritov's basic finding. We used structural equation modelling to test four possible explanations for cheating-sense of entitlement, self-confidence, feeling lucky and inequality aversion. Only inequality aversion turned out to be significantly associated with cheating.

Learning to cooperate without awareness in multiplayer minimal social situations.

Experimental and Monte Carlo methods were used to test theoretical predictions about adaptive learning of cooperative responses without awareness in minimal social situations-games in which the payoffs to players depend not on their own actions but exclusively on the actions of other group members. In Experiment 1, learning occurred slowly over 200 rounds in a dyadic minimal social situation but not in multiplayer groups. In Experiments 2-4, learning occurred rarely in multiplayer groups, even when players were informed that they were interacting strategically and were allowed to communicate with one another but were not aware of the game's payoff structure. Monte Carlo simulation suggested that players approach minimal social situations using a noisy version of the win-stay, lose-shift decision rule, deviating from the deterministic rule less frequently after rewarding than unrewarding rounds.

Do say "thank you": verbal expressions of politeness and gratitude influence interpersonal perceptions.

This study investigates how expressions of politeness and gratitude influence interpersonal perceptions of a job interviewee's trustworthiness and personality. A pilot study disentangled politeness and gratitude ratings for phrases. Statements expressing politeness with high or low gratitude were selected and inserted into a job-interview transcript, with the female interviewee depicted as either the same age or 20 years older than the 136 participants. Results showed that, irrespective of the speaker's perceived age, expressing politeness significantly improved the overall impression that the female interviewee made (likeable, friendly, employable and trustworthy) and did not reduce how assertive she appeared. Expressing higher gratitude reduced formality and increased friendliness ratings. We conclude that expressing politeness and gratitude impacts positively on perceptions of women, in line with Politeness Theory.

Verbal expressions of confidence and doubt.

The development of a taxonomy of expressions expressing the degree of confidence or certainty felt in the correctness of one's judgments, knowledge, or beliefs is reported. 30 phrases expressing confidence and doubt were rated by 96 British participants on a 7-point scale to indicate how much confidence or doubt they felt each phrase expressed. The expressions were rank ordered, based on their mean ratings, to produce a continuum of cues expressing confidence, ranging from high to low. 9 of the 30 expressions were rated as expressing lower confidence when phrased in the past tense than in the present tense. The expressions reported in this study form a useful tool for researchers who are investigating the communication of confidence and degrees of belief, especially in relation to giving advice, influence, and persuasion.

Team reasoning and collective rationality: piercing the veil of obviousness.

The experiments reported in our target article provide strong evidence of collective utility maximization, and the findings suggest that team reasoning should now be included among the social value orientations used in cognitive and social psychology. Evidential decision theory offers a possible alternative explanation for our results but fails to predict intuitively compelling strategy choices in simple games with asymmetric team-reasoning outcomes. Although many of our experimental participants evidently used team reasoning, some appear to have ignored the other players' expected strategy choices and used lower-level, nonstrategic forms of reasoning. Standard payoff transformations cannot explain the experimental findings, nor team reasoning in general, without an unrealistic assumption that players invariably reason nonstrategically.

Collective rationality in interactive decisions: evidence for team reasoning.

Decision theory and game theory rest on a fundamental assumption that players seek to maximize their individual utilities, but in some interactive decisions it seems intuitively reasonable to aim to maximize the utility of the group of players as a whole. Such team reasoning requires collective preferences and a distinctive mode of reasoning from preferences to decisions. Findings from two experiments provide evidence for collective preferences and team reasoning. In lifelike vignettes (Experiment 1) and abstract games (Experiment 2) with certain structural properties, most players preferred team-reasoning strategies to strategies supporting unique Nash equilibria, although individually rational players should choose equilibrium strategies. These findings suggest that team reasoning predicts strategy choices more powerfully than orthodox game theory in some games.

Size doesn't really matter: ambiguity aversion in Ellsberg urns with few balls.

When attempting to draw a ball of a specified color either from an urn containing 50 red balls and 50 black balls or from an urn containing an unknown ratio of 100 red and black balls, a majority of decision makers prefer the known-risk urn, and this ambiguity aversion effect violates expected utility theory. In an experimental investigation of the effect of urn size on ambiguity aversion, 149 participants showed similar levels of aversion when choosing from urns containing 2, 10, or 100 balls. The occurrence of a substantial and significant ambiguity aversion effect even in the smallest urn suggests that influential theoretical interpretations of ambiguity aversion may need to be reconsidered.

Market entry decisions: effects of absolute and relative confidence.

In a market entry game, the number of entrants usually approaches game-theoretic equilibrium quickly, but in real-world markets business start-ups typically exceed market capacity, resulting in chronically high failure rates and suboptimal industry profits. Excessive entry has been attributed to overconfidence arising when expected payoffs depend partly on skill. In an experimental test of this hypothesis, 96 participants played 24 rounds of a market entry game, with expected payoffs dependent partly on skill on half the rounds, after their confidence was manipulated and measured. The results provide direct support for the hypothesis that high levels of confidence are largely responsible for excessive entry, and they suggest that absolute confidence, independent of interpersonal comparison, rather than confidence about one's abilities relative to others, drives excessive entry decisions when skill is involved.

Persistent cooperation and gender differences in repeated Prisoner's Dilemma games: Some things never change.

In the finite-horizon repeated Prisoner's Dilemma, a compelling backward induction argument shows that rational players will defect in every round, following the uniquely optimal Nash equilibrium path. It is frequently asserted that cooperation gradually declines when a Prisoner's Dilemma is repeated multiple times by the same players, but the evidence for this is unconvincing, and a classic experiment by Rapoport and Chammah in the 1960s reported that cooperation eventually recovers if the game is repeated hundreds of times. They also reported that men paired with men cooperate almost twice as frequently as women paired with women. Our conceptual replication with Prisoner's Dilemmas repeated over 300 rounds with no breaks, using more advanced, computerized methodology, revealed no decline in cooperation, apart from endgame effects in the last few rounds, and replicated the substantial gender difference, confirming, in the UK, a puzzling finding first reported in the US in the 1960s.

Dynamic probability of reinforcement for cooperation: Random game termination in the centipede game.

Experimental games have previously been used to study principles of human interaction. Many such games are characterized by iterated or repeated designs that model dynamic relationships, including reciprocal cooperation. To enable the study of infinite game repetitions and to avoid endgame effects of lower cooperation toward the final game round, investigators have introduced random termination rules. This study extends previous research that has focused narrowly on repeated Prisoner's Dilemma games by conducting a controlled experiment of two-player, random termination Centipede games involving probabilistic reinforcement and characterized by the longest decision sequences reported in the empirical literature to date (24 decision nodes). Specifically, we assessed mean exit points and cooperation rates, and compared the effects of four different termination rules: no random game termination, random game termination with constant termination probability, random game termination with increasing termination probability, and random game termination with decreasing termination probability. We found that although mean exit points were lower for games with shorter expected game lengths, the subjects' cooperativeness was significantly reduced only in the most extreme condition with decreasing computer termination probability and an expected game length of two decision nodes.

The persuasive power of knowledge: Testing the confidence heuristic.

According to the confidence heuristic, people are confident when they know they are right, and their confidence makes them persuasive. Previous experiments have investigated the confidence-persuasiveness aspect of the heuristic but not the integrated knowledge-confidence-persuasiveness hypothesis. We report 3 experiments to test the heuristic using incentivized interactive decisions with financial outcomes in which pairs of participants with common interests attempted to identify target stimuli after conferring, only 1 pair member having strong information about the target. Experiment 1, through the use of a facial identification task, confirmed the confidence heuristic. Experiment 2, through the use of geometric shapes as stimuli, elicited a much larger confidence heuristic effect. Experiment 3 found similar confidence heuristic effects through both face-to-face and computer-mediated communication channels, suggesting that verbal rather than nonverbal communication drives the heuristic. Suggesting an answer first was typical of pair members with strong evidence and might therefore be a dominant cue that persuades. Our results establish the confidence heuristic with dissimilar classes of stimuli and through different communication channels. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Social Value Induction and Cooperation in the Centipede Game.

The Centipede game provides a dynamic model of cooperation and competition in repeated dyadic interactions. Two experiments investigated psychological factors driving cooperation in 20 rounds of a Centipede game with significant monetary incentives and anonymous and random re-pairing of players after every round. The main purpose of the research was to determine whether the pattern of strategic choices observed when no specific social value orientation is experimentally induced--the standard condition in all previous investigations of behavior in the Centipede and most other experimental games--is essentially individualistic, the orthodox game-theoretic assumption being that players are individualistically motivated in the absence of any specific motivational induction. Participants in whom no specific state social value orientation was induced exhibited moderately non-cooperative play that differed significantly from the pattern found when an individualistic orientation was induced. In both experiments, the neutral treatment condition, in which no orientation was induced, elicited competitive behavior resembling behavior in the condition in which a competitive orientation was explicitly induced. Trait social value orientation, measured with a questionnaire, influenced cooperation differently depending on the experimentally induced state social value orientation. Cooperative trait social value orientation was a significant predictor of cooperation and, to a lesser degree, experimentally induced competitive orientation was a significant predictor of non-cooperation. The experimental results imply that the standard assumption of individualistic motivation in experimental games may not be valid, and that the results of such investigations need to take into account the possibility that players are competitively motivated.

Correction: Social Value Induction and Cooperation in the Centipede Game.

[This corrects the article DOI: 10.1371/journal.pone.0152352.].

Personality differences in high risk sports amateurs and instructors.

This study investigated the personality differences of 21 amateurs and 20 instructors who participated in the high risk sports of skydiving, hang-gliding, paragliding, scuba diving, microlighting, and rock climbing, versus those who did not. 38 men and 28 women (M age=32.6 yr., SD= 10.0) were assessed using the Eysenck Personality Questionnaire-Revised, the General Health Questionnaire, the Generalised Self-efficacy Scale, and a Type A/B personality measure. Instructors and Amateurs scored significantly higher on Extroversion and lower on Neuroticism than Nonparticipants; however, they differed from each other on the General Health Questionnaire and Type A/B personality scores. Amateurs scored significantly higher on Psychoticism and Self-efficacy than Instructors and Nonparticipants. In conclusion, these test scores suggest that people who are attracted to high risk sports tend to be at the extroverted and emotionally stable end of the scale, with a tendency to exhibit Type A characteristics; however, Instructors' scores on Psychoticism and Self-efficacy are more akin to those of Nonparticipants.

The outlandish, the realistic, and the real: contextual manipulation and agent role effects in trolley problems.

Hypothetical trolley problems are widely used to elicit moral intuitions, which are employed in the development of moral theory and the psychological study of moral judgments. The scenarios used are outlandish, and some philosophers and psychologists have questioned whether the judgments made in such unrealistic and unfamiliar scenarios are a reliable basis for theory-building. We present two experiments that investigate whether differences in moral judgment due to the role of the agent, previously found in a standard trolley scenario, persist when the structure of the problem is transplanted to a more familiar context. Our first experiment compares judgments in hypothetical scenarios; our second experiment operationalizes some of those scenarios in the laboratory, allowing us to observe judgments about decisions that are really being made. In the hypothetical experiment, we found that the role effect reversed in our more familiar context, both in judgments about what the actor ought to do and in judgments about the moral rightness of the action. However, in our laboratory experiment, the effects reversed back or disappeared. Among judgments of what the actor ought to do, we found the same role effect as in the standard hypothetical trolley scenario, but the effect of role on moral judgments disappeared.

Strong Stackelberg reasoning in symmetric games: An experimental replication and extension.

In common interest games in which players are motivated to coordinate their strategies to achieve a jointly optimal outcome, orthodox game theory provides no general reason or justification for choosing the required strategies. In the simplest cases, where the optimal strategies are intuitively obvious, human decision makers generally coordinate without difficulty, but how they achieve this is poorly understood. Most theories seeking to explain strategic coordination have limited applicability, or require changes to the game specification, or introduce implausible assumptions or radical departures from fundamental game-theoretic assumptions. The theory of strong Stackelberg reasoning, according to which players choose strategies that would maximize their own payoffs if their co-players could invariably anticipate any strategy and respond with a best reply to it, avoids these problems and explains strategic coordination in all dyadic common interest games. Previous experimental evidence has provided evidence for strong Stackelberg reasoning in asymmetric games. Here we report evidence from two experiments consistent with players being influenced by strong Stackelberg reasoning in a wide variety of symmetric 3 × 3 games but tending to revert to other choice criteria when strong Stackelberg reasoning generates small payoffs.