The force of symmetry revisited: symmetry-to-noise ratios regulate (a)symmetry effects

Freyd and Tversky's [Am. J. Psychol. 97 (1984) 109] data suggested that human observers tend to overestimate relatively high levels of symmetry (symmetry effect), and tend to underestimate relatively low levels of symmetry (asymmetry effect). However, on the basis of their holographic approach to visual regularity, van der Helm and Leeuwenberg [Psychol. Rev. 103(3) (1996) 429] predicted that, at any level of symmetry, both symmetry and asymmetry effects may occur as a consequence of correct estimates of symmetry-to-noise ratios. This prediction was tested in two experiments, with tasks and stimuli similar to those in Freyd and Tversky's study. First, subjects had to judge whether a noisy symmetry is more similar to a slightly more symmetrical variant or to a slightly less symmetrical variant. Second, for every pair of stimuli in such a triadic comparison, subjects had to judge which stimulus is the more symmetrical one. The results from both experiments show that the occurrence of (a)symmetry effects indeed depends on symmetry-to-noise ratios.     

Development of the coordination between posture and manual control

Studies have suggested that proper postural control is essential for the development of reaching. However, little research has examined the development of the coordination between posture and manual control throughout childhood. We investigated the coordination between posture and manual control in children (7- and 10-year-olds) and adults during a precision fitting task as task constraints became more difficult. Participants fit a block through an opening as arm kinematics, trunk kinematics, and center of pressure data were collected. During the fitting task, the precision, postural, and visual constraints of the task were manipulated. Young children adopted a strategy where they first move their trunk toward the opening and then stabilize their trunk (freeze degrees of freedom) as the precision manual task is being performed. In contrast, adults and older children make compensatory trunk movements as the task is being performed. The 10-year-olds were similar to adults under the less constrained task conditions, but they resembled the 7-year-olds under the more challenging tasks. The ability to either suppress or allow postural fluctuations based on the constraints of a suprapostural task begins to develop at around 10 years of age. This ability, once developed, allows children to learn specific segmental movements required to complete a task within an environmental context.     

Are social value orientations expressed automatically? Decision making in the dictator game

Drawing on the social intuitionist model, the authors studied the hypothesis that social value orientations are expressed automatically in behavior. They compared spontaneous and more deliberated decisions in the dictator game and confirmed that social values determine behavior when responses are based on the automatic system. By means of both mediation and experimental analyses, the authors further demonstrate that the automatic expression of social value orientations is mediated by perceptions of interpersonal closeness. A reasoning process can subsequently override these automatic responses and disconnect decisions from perceptions of interpersonal closeness. This results in lower levels of other-regarding behavior, at least for prosocials.     

Self-Perceived Effects of Pornography Consumption in a Sample of Indonesian University Students

Self-perceived effects of pornography consumption were studied in a sample of university students in Indonesia—a conservative, Muslim majority country with strict anti-pornography laws. Using a cross-sectional design and a modified version of the Pornography Consumption Effect Scale (PCES), we assessed participants' reports of how pornography affected their sexual knowledge, attitude toward sex, sex life, perception of and attitude toward the opposite gender, and life in general. The area of attitude toward sex excepted, the study found that both men and women reported significantly larger positive than negative effects. Further, as compared to women, men reported significantly larger negative effects of their pornography consumption. For both genders, pornography-related variables were found to add significantly to the prediction of both positive and negative self-perceived effects of pornography consumption over and above a number of included control variables.     

Special issue on indigenising educational psychology

The Journal of Psychology in Africa (JPA) is a peer-reviewed journal co-published NISC (Pty) Ltd and Informa UK Limited (trading as Taylor & Francis Group) on behalf of Africa Scholarship Development Enterprize. It is accredited by the Department of Higher Education and Training in South Africa and indexed in the ISI Web of Science. The JPA provides an inter-disciplinary forum for the dissemination of psychological research in Africa and related regions in the context of development. Its core mission is to advance psychological research for the social-cultural and health development in Africanist settings, inclusive of the African diaspora communities around the globe. Research that addresses African heritage realities and opportunities is particularly encouraged. Contributions should attempt a synthesis of local and universal methodologies and applications, contributing to the wider body of knowledge in the applied psychological sciences.     

Which cues are available to 24-month-olds? Evidence from point-of-gaze measures during search

In previous research 2-year-olds have failed to show knowledge of solidity in a search task in which a ball rolled behind a screen and was stopped by a barrier. The screen had four doors and the barrier was visible above the door hiding the ball. To establish what cues 2-year-olds might be using, precise point-of-gaze measures were taken during the hiding event. A transparent screen with opaque doors provided two cues: (1) the ball could be tracked until it failed to emerge, and (2) the barrier's position could indicate the correct door. Point-of-gaze measures revealed that children failed to use the more indirect cue of the barrier, which requires reasoning and spatial integration. Their search success was predicted only by the more immediate cue of actively tracking the ball. These findings support the claim that children use best those cues directly related to the object's disappearance, while failing to use cues that entail higher cognitive demands.