Effects of limited peripheral vision on shuttle sprint performance of soccer players

This study examined the effect of limited peripheral vision on the shuttle sprint performance of soccer players. Participants were 14 male soccer players of a student soccer club (M age = 22.1 yr., SD = 1.3 yr.). They performed a repeated shuttle sprint with full and limited peripheral vision. Mean total sprint time and mean turning time increased significantly with limited peripheral vision. It is concluded that only turning during shuttle sprint performance decreases when sprinting with a restricted peripheral field of view, indicating the use of peripheral vision for the control of directional changes while sprinting.     

Mechanisms of autobiographical memory retrieval in younger and older adults

In this study, retrieval of autobiographical memories was compared within or without the context of a lifetime period and between younger and older adults. The results of two experiments demonstrated that memories were more accessible for younger and older adults when they were retrieved within a time period context than without such context. However, when the retrieval context was more constrained and limited to cue word memories, the benefit of retrieval context disappeared. The results also suggested that as compared with younger adults, older adults were more likely to selectively retain memories with distinctive characteristics, such as being self-relevant and emotionally intense, particularly when remote memories were involved. Mechanisms of autobiographical memory retrieval in younger and older adults.     

Self and partner personality and responses to relationship threats

Two studies examined the relations between three different types of jealousy and personality characteristics of self and partner in two large heterogeneous community samples of heterosexual couples (459 and 230 couples, respectively). It was expected that partners would resemble each other to some extent in both the experience of different types of jealousy and personality characteristics, and that self-reported levels of neuroticism (+) and extraversion (−) would be related to higher levels of jealousy. Moreover, it was expected that partner extraversion would be related positively to levels of jealousy, and that similarity with regard to personality characteristics would be related to lower levels of jealousy. Results largely supported our expectations with regard to both partner similarity and self-reported personality characteristics. However, our expectations with regard to partner extraversion and similarity were not supported.     

Do physical and relational aggression explain adolescents' friendship selection? The competing roles of network characteristics,gender, and social status

The role of physical and relational aggression in adolescents' friendship selection was examined in a longitudinal sample of 274 Chilean students from 5th and 6th grade followed over 1 year. Longitudinal social network modeling (SIENA) was used to study selection processes for aggression while influence processes were controlled for. Furthermore, the effects of network characteristics (i.e., reciprocity and transitivity), gender, and social status on friendship selection were examined. The starting assumption of this study was that selection effects based on aggression might have been overestimated in previous research as a result of failing to consider influence processes and alternative characteristics that steer friendship formation. The results show that selection effects of both physical and relational aggression disappeared when network effects, gender, and social status were taken into account. Particularly gender and perceived popularity appeared to be far more important determinants of friendship selection over time than aggression. Moreover, a peer influence effect was only found for relational aggression, and not for physical aggression. These findings suggest that similarity in aggression among befriended adolescents can be considered to be mainly a by-product rather than a leading dimension in friendship selection.     

Self-efficacy expectations with regard to different tasks in smoking cessation

Abstract

Self-efficacy expectations are important psychological determinants of smoking cessation. The present study aimed at exploring different sorts of self-efficacy. The following self-efficacy scales were composed: Emotional self-efficacy, Social self-efficacy, Skill self-efficacy, Relapse self-efficacy and Try self-efficacy. In a sample of 752 smokers with low motivation to quit, two subsequent self-report measurements of self-efficacy were conducted. Firstly, we investigated to what extent potential sources of self-efficacy - quitting history and smoking behavior -were related to the types of self-efficacy. The explained variance in self-efficacy scores ranged from 4.4% to 23.1%, and in all five types of self-efficacy, smoking behaviour explained a higher percentage of self-efficacy than quitting history. The number of past quit attempts was only related to Relapse self-efficacy. Secondly, we investigated to what extent the different types of self-efficacy at T1 were predictive of quitting behavior measured at T2. The results showed that only Skill self-efficacy was predictive of quitting activity between Tl and T2. Point prevalence quitting at T2 was predicted by Skill self-efficacy and Relapse self-efficacy. The latter type of self-efficacy, however, was a negative predictor of quitting. The different types of self-efficacy can be mapped on two dimensions: The extent to which the means to accomplish a certain task are specified in the questionnaire item; and the phase of behavior change to which the self-efficacy tasks are relevant. Based on the findings from the predictive validity, it is concluded that the more clearly the means to accomplish the task are specified, the more valid the self-efficacy judgements are.     

Conditions for factor (in)determinacy in factor analysis

The subject of factor indeterminacy has a vast history in factor analysis (Guttman, 1955; Lederman, 1938; Wilson, 1928). It has lead to strong differences in opinion (Steiger, 1979). The current paper gives necessary and sufficient conditions for observability of factors in terms of the parameter matrices and a finite number of variables. Five conditions are given which rigorously define indeterminacy. It is shown that (un)observable factors are (in)determinate. Specifically, the indeterminacy proof by Guttman is extended to Heywood cases. The results are illustrated by two examples and implications for indeterminacy are discussed.