Information and action in punching a falling ball

Lee, Young, Reddish, Lough, and Clayton (1983) reported that the timing control of jumping and vertically punching a dropping ball exploits the inverse of the rate of change of optical expansion, τ(r). We raise a number of methodological and logical criticisms against their experiment and conclusions and attempt to rectify them by examining elbow joint angles only,in seated punchers, under both monocular and binocular conditions, with two ball sizes, dropped from two heights. Differences between the binocular and monocular cases suggest the exploitation of different information. We present several techniques to help determine the operative variable(s) controlling the action. The optical variable used to initiate and guide flexion appeared to be expansion velocity (looming), rather than τ(r); extension appeared to be under the control of different variables in the monocular and binocular cases. Simulations using single variables and single perceptuo-motor intervals were of mixed success.     

Suicide Clusters: A Review of Risk Factors and Mechanisms

Suicide clusters, although uncommon, cause great concern in the communities in which they occur. We searched the world literature on suicide clusters and describe the risk factors and proposed psychological mechanisms underlying the spatio‐temporal clustering of suicides (point clusters). Potential risk factors include male gender, being an adolescent or young adult, drug or alcohol abuse, and past history of self‐harm. However, the majority of studies lack methodological rigor. Many different psychological mechanisms are described, including contagion, imitation, suggestion, learning, and assortative relating, but supporting empirical evidence is generally lacking. More scientifically rigorous studies are needed to improve understanding of suicide clusters.     

The Definition and Epidemiology of Clusters of Suicidal Behavior: A Systematic Review

Suicide clusters are a rare and underresearched phenomenon which attract wide media attention and result in heightened concern in the communities where they occur. We conducted a systematic literature review covering the definition and epidemiology of the time–space clustering of suicidal behavior. Of the 890 articles identified by electronic searching, 82 were selected for inclusion and the extracted data were analyzed by narrative synthesis. Less than a third of studies included a definition of a suicide cluster, and definitions varied considerably. Clusters occurred in various settings, including psychiatric hospitals, schools, prisons, indigenous communities, and among the general population. Most clusters involved young people. The proportion of all episodes that occurred in clusters varied considerably between studies and partly depended on study methodology (e.g., a larger proportion was found in studies of specific clusters compared with general population studies). Future studies should aim to combine the statistical analysis of time–space clustering with a case study of events, which examines potential links between individuals and the wider environmental context.     

Instrumental Outcome Devaluation Is Attenuated by the Anti-emetic Ondansetron

In three experiments we assessed the effect of an anti-emetic, the selective S-HT antagonist ondansetron, on (1) the conditioning of a taste aversion using lithium chloride (LiCl); (2) the expression of that aversion; and (3) instrumental outcome-devaluation effects. In Experiment 1 it was found that ondansetron reduced the aversion induced by LiCl when administered prior to the LiCl injection and also attenuated the expression of that aversion when administered prior to test sessions. In Experiments 2 and 3, thirsty rats were trained, in a single session, to lever press and chain pull for sucrose and saline solutions concurrently before being injected with LiCl. They were then re-exposed to both solutions, one after injection of vehicle and the other after injection of ondansetron. In a choice extinction test on the levers and chains, animals performed more of the action whose training outcome was re-exposed under ondansetron than the other action, whether the test was conducted after an injection of vehicle or after one of ondansetron.     

Is Cumulative Exposure to Suicide Attempts and Deaths a Risk Factor for Suicidal Behavior Among Firefighters? A Preliminary Study

The association between cumulative exposure to suicide attempts and deaths and suicidal behavior was examined in a sample of 61 professional firefighters. On average, firefighters reported 13.1 (SD = 16.6) exposures over the course of their lifetime. Cumulative exposure to suicide attempts and deaths was positively correlated with suicidal behavior (r = .38, p = .004). Moreover, firefighters with 12+ exposures were more likely to screen positive for risk of suicidal behavior (OR = 7.885, p = .02). Additional research on the potential impact of cumulative exposure to suicide attempts and deaths on firefighters' health and safety is needed.     

Friendships in middle childhood: Links to peer and school identification,and general self-worth

Children's friendships are important for well-being and school adjustment, but few studies have examined multiple indices of friendships together in middle childhood. The current study surveyed 7- to 11-year-olds (n = 314) about their friendships, best friendships, friendship quality and indices of self-worth, identification with peers, and identification with school. Peer relationships were positively related to self-worth, but not identification with peers or school. Best friendship quality moderated the relationship between number of reciprocated friendship nominations and self-worth. Children with a reciprocated best friend had higher friendship quality and peer identification than others. Where best friendship was reciprocated, the relationship with identification with peers was mediated via positive friendship quality. The results suggest that friendship reciprocity is particularly relevant for children's self-worth and identification with peers. The findings are discussed in relation to the importance of fostering the development of reciprocated friendships.

Statement of contribution

What is already known on this subject?

• Friendships are related to well-being, school relations, and how young people feel about their peers at school.
• Friendship quality may be important in moderating the relationship between peer relations and adjustment.

What does this study add?

• Various aspects of friendships are studied simultaneously with younger children than much previous research.
• Reciprocated best friendships were better quality than partial or non-reciprocated best friendships.
• Friendship reciprocity was most relevant for children's self-worth and peer identification.