(1) Background: Self-talk (ST) is used to influence athletes’ thoughts, feelings, and behaviors. Samples of squad and competitive athletes are underrepresented, although research has proven the positive effects of ST in the context of sports. Thus, the present study focused on the impact of ST on psychological and performance outcomes of junior sub-elite athletes. (2) Methods: N = 117 athletes (55 females, 62 males; M = 16.0 years) were randomly assigned to either one of two experimental groups or to a control group (n = 30). The experimental groups received an ST intervention for either one week (n = 36) or eight weeks (n = 38), and the control group received no ST training. The dependent variables (competitive anxiety, volitional skills, self-efficacy, and coaches’ performance ratings) were assessed three times before and after the intervention. It was expected that (a) an ST intervention would reduce the competitive anxiety and increase volitional skills, self-efficacy, and performance; and, (b) long-term training would lead to higher effects than short-term training. (3) Results: As expected, ST training led to (less) somatic state anxiety and (higher) state self-confidence, self-optimization, self-efficacy, and performance. Additionally, long-term training was more effective than short-term training. (4) Conclusions: Targeted ST interventions may help to improve junior athletes’ psychological states and performance.

People’s general tendencies to view others as cold-hearted and manipulative (rather than affectionate and trustworthy) may explain defection in social dilemma situations. To capture idiosyncratic tendencies in other-perceptions, we collected mutual judgments in groups of unacquainted individuals in two studies (N1 = 83, N2 = 413) and extracted perceiver effect scores using the Social Relations Model. In both studies, participants later played a public goods game. In Study 1, perceiver effects predicted cooperation beyond self-reported and group-related control variables. However, results were not replicated in a preregistered second study with higher power and a more diverse sample. We discuss implicit group norms as a likely explanation for the inconsistent findings and suggest future directions for addressing generalized expectations in social dilemmas.

This study compared the impacts of actual individual task competence, speaking time and physical expressiveness as indicators of verbal and nonverbal communication behavior, and likability on performance evaluations in a group task. 164 participants who were assigned to 41 groups first solved a problem individually and later solved it as a team. After the group interaction, participants’ performance was evaluated by both their team members and qualified external observers. We found that these performance evaluations were significantly affected not only by task competence but even more by speaking time and nonverbal physical expressiveness. Likability also explained additional variance in performance evaluations. The implications of these findings are discussed for both the people being evaluated and the people doing the evaluating.

On the basis of the input-process-output model, the present research examined how individual performance, interpersonal attraction, and interpersonal behavior affect group performance in a problem-solving task. 164 participants were assigned to 41 groups, each consisting of four same-sex members. Participants completed a measure of interpersonal attraction and individually solved the established moon-landing task. Afterwards, all group members worked together to find a common solution for this task. Four interpersonal behaviors were recorded on video while the group interacted (cooperative, communicative, coordinative, and conflict behavior). Two main findings emerged: First, on average, groups performed better than the individuals did alone. Second, individual performance, interpersonal attraction, and directly observed interpersonal behaviors were independent predictors of group performance. Furthermore, we found indications that interpersonal behavior might play a mediating role here. The results and their implications are discussed.