Coordinated behavior patterns are one of the pillars of social interaction. Researchers have recently shown that movement synchrony influences ratings of rapport, and the extent to which groups are judged to be a unit. The current experiments investigated the hypothesis that observers infer a shared psychological state from synchronized movement rhythms, influencing attributions of rapport and entitativity judgments. Movement rhythms of observed individuals are manipulated between participants (Experiment 1) or kept constant while the source of the emerging movement synchrony is manipulated (Experiment 2), and both rapport and perceived entitativity are measured. The findings support the assumption that movement synchrony increases attributed rapport and perceived entitativity. Furthermore, mediational analyses reveal that the effects of movement synchrony on perceived unity are not purely perceptual in nature, but caused by psychological inferences. Observers infer the degree to which individuals are a social unit from their movement rhythms.Coordinated behavior patterns are one of the pillars of social interaction. Peoples' movement rhythms can synchronize unintentionally, for example when walking side by side, or intentionally, as when military units march. The tendency to synchronize movement rhythms has been theorized to play an important role in the formation of a social unit (Condon

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When comparing two independent groups, researchers in Psychology commonly use Student’s t-test. Assumptions of normality and of homogeneity of variance underlie this test. More often than not, when these conditions are not met, Student’s t-test can be severely biased, and leads to invalid statistical inferences. Moreover, we argue that the assumption of equal variances will seldom hold in psychological research and that choosing between Student’s t-test or Welch’s t-test based on the outcomes of a test of the equality of variances often fails to provide an appropriate answer. We show that the Welch’s t-test provides a better control of Type 1 error rates when the assumption of homogeneity of variance is not met, and loses little robustness compared to Student’s t-test when the assumptions are met. We argue that Welch’s t-test should be used as a default strategy.

Robust scientific knowledge is contingent upon replication of original findings. However, researchers who conduct replication studies face a difficult problem; there are many more studies in need of replication than there are funds available for replicating. To select studies for replication efficiently, we need to understand which studies are the most in need of replication. In other words, we need to understand which replication efforts have the highest expected utility. In this article we propose a general rule for study selection in replication research based on the replication value of the claims considered for replication. The replication value of a claim is defined as the maximum expected utility we could gain by replicating the claim, and is a function of (1) the value of being certain about the claim, and (2) uncertainty about the claim based on current evidence. We formalize this definition in terms of a causal decision model, utilizing concepts from decision theory and causal graph modeling. We discuss the validity of using replication value as a measure of expected utility gain, and we suggest approaches for deriving quantitative estimates of replication value.

The Action-sentence Compatibility Effect (ACE) is a well-known demonstration of the role of motor activity in the comprehension of language. Participants are asked to make sensibility judgments on sentences by producing movements toward the body or away from the body. The ACE is the finding that movements are faster when the direction of the movement (e.g., toward) matches the direction of the action in the to-be-judged sentence (e.g., Art gave you the pen describes action toward you). We report on a pre-registered, multi-lab replication of one version of the ACE. The results show that none of the 18 labs involved in the study observed a reliable ACE, and that the meta-analytic estimate of the size of the ACE was essentially zero.