Psychological scientists have become increasingly concerned with issues related to methodology and replicability, and infancy researchers in particular face specific challenges related to replicability: For example, high-powered studies are difficult to conduct, testing conditions vary across labs, and different labs have access to different infant populations. Addressing these concerns, we report on a large-scale, multisite study aimed at (a) assessing the overall replicability of a single theoretically important phenomenon and (b) examining methodological, cultural, and developmental moderators. We focus on infants’ preference for infant-directed speech (IDS) over adult-directed speech (ADS). Stimuli of mothers speaking to their infants and to an adult in North American English were created using seminaturalistic laboratory-based audio recordings. Infants’ relative preference for IDS and ADS was assessed across 67 laboratories in North America, Europe, Australia, and Asia using the three common methods for measuring infants’ discrimination (head-turn preference, central fixation, and eye tracking). The overall meta-analytic effect size (Cohen’s d) was 0.35, 95% confidence interval = [0.29, 0.42], which was reliably above zero but smaller than the meta-analytic mean computed from previous literature (0.67). The IDS preference was significantly stronger in older children, in those children for whom the stimuli matched their native language and dialect, and in data from labs using the head-turn preference procedure. Together, these findings replicate the IDS preference but suggest that its magnitude is modulated by development, native-language experience, and testing procedure.

This research investigated whether emotional hyporeactivity affects moral judgements and choices of action in sacrificial moral dilemmas and in everyday moral conflict situations in which harm to other's welfare is differentially involved. Twenty-six participants with high trait psychopathy (HP) and 25 with low trait psychopathy (LP) were selected based on the primary psychopathy scale of the Levenson Self-Report Psychopathy Scale. HP participants were more likely to sacrifice one person to save others in sacrificial dilemmas and to pursue a personal advantage in everyday moral situations entailing harm to another's good. While deciding in these situations, HP participants experienced lower unpleasantness as compared to LP participants. Conversely, no group differences emerged in choice of action and unpleasantness ratings for everyday moral situations that did not entail harm to others. Importantly, moral judgements did not differ in the two groups. These results suggest that high psychopathy trait affects choices of action in sacrificial dilemmas because of reduced emotional reactivity to harmful acts. The dissociation between choice of action and moral judgement suggests that the former is more closely related to emotional experience. Also, emotion seems to play a critical role in discriminating harmful from harmless acts and in driving decisions accordingly.

The moral self-concept reflects the view of oneself in terms of moral behavior and has been proposed to predict actual behavior. Theories also suggest emotions and emotion knowledge to predict prosocial behavior, but the interplay between the moral self-concept and emotions is largely unknown. This interplay is especially important to study in middle childhood, a relevant period for the ontogeny of the moral self-concept and when emotions regarding prosocial behavior are suggested to change. The current study explored the nature of the relation between the moral self-concept, prosocial behavior, and consequential emotions (Experiment 1) or anticipated emotions (Experiment 2) regarding prosocial behavior in 5-to 9-year-olds (together N=169). Moreover, we investigated whether emotions mediate the relation between the moral self-concept and prosocial behavior. Overall, the moral self-concept was positively related to prosocial behavior. In addition, emotional consequences as well as anticipated emotions explained age differences in sharing behavior. Moreover, the results hint to an indirect effect of the moral self-concept on sharing behavior through the anticipation of negative feelings when not-sharing. Interestingly, children who first reflected about the affective consequences of prosocial behavior seemed to share more. In line with theories, the results demonstrate that both the moral self-concept and emotions are relevant motivators of prosocial behavior in middle childhood.

Recent theories have highlighted the relevance of the moral self-concept (MSC) for prosocial behavior. Its early development and internal structure is still unknown, though. With two studies, we aimed to investigate the structure of the MSC in early childhood. Furthermore, we explored prosocial behavioral correlates (helping, sharing, comforting). In a first study, we explored four to six-year-olds (N = 127). We assessed explicit (puppet-interview) and implicit (IAT) measures of the MSC and observed child behavior. Our results show that MSC was independent from other self-concept domains. The three prosocial dimensions (helping, sharing and comforting) appear to be represented within the MSC separately. While the IAT yielded no significant relations with behaviors, the explicit MSC was meaningfully related to prosocial behavior. The second study (N = 314) underscores the results of the first, by replicating the factor structure of the MSC in confirmatory factor analysis. In conclusion, the studies underscore the MSC's different dimensions and their relations to prosocial behaviors in preschool children.

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