Interaction between catecholaminergic and opioid systems in an active avoidance task

Male NMRI mice were given intravenous injections of the noradrenergic neurotoxin DSP4 or the vehicle 24 to 72 h prior behavioral testing. Animals were given 2 days of training on a one-way active avoidance task. Naloxone was given in one of three doses prior to training on Day 1 and Day 2 or prior to training on Day 1 only (saline was given prior to training on Day 2). There was a dose-dependent impairment of acquisition by naloxone in the vehicle-pretreated groups; 10 mg/kg naloxone produced a significant impairment of acquisition. Naloxone also modulated retention (Day 2) performance of the active avoidance task. For vehicle-pretreated mice, 1 mg/kg naloxone facilitated and 10 mg/kg naloxone-impaired performance on Day 2. DSP4 alone produced an impairment of acquisition of this task but had no effect on retention; Day 2 scores were slightly higher in the DSP4-pretreated group than in the vehicle-pretreated group. Naloxone produced somewhat different effects in DSP4-pretreated animals than in vehicle-pretreated animals. Naloxone (1 mg/kg) ameliorated the DSP4-induced impairment of acquisition; 10 mg/kg naloxone did not significantly alter the acquisition performance of this group. For the DSP4-pretreated mice that received naloxone before training on both days, the dose-response characteristics for retention scores were similar to those of vehicle-pretreated mice; 1 mg/kg naloxone was the facilitatory dose. However, for DSP4-treated mice that received naloxone before training on Day 1 only, there was a shift to the right in the effective facilitatory dose of naloxone. For these animals, 10 mg/kg naloxone but not 1 mg/kg naloxone significantly enhanced retention performance. We discuss these results in the context of a possible state-dependent modulation by naloxone in the DSP4-treated animals.     

The perception of preschool social dominance

Children's and teachers' perception of social dominance was examined using a behavioral criterion for determining accuracy of verbal judgments. Video records of agonistic interactions were obtained during approximately 60 hours of free-play at two preschool centers. Analyses of social conflict episodes ending in submission revealed linear dominance structures for both groups. Dominance perception was assessed in two ways. Both teachers and children were asked to rank-order a subgroup of children according to dominance. They were also asked to select the more dominant children in a number of predetermined pairs. Results indicated that teachers could accurately judge dyadic dominance relations, and that accuracy among children varied as a function of their status within the group hierarchy. Findings have implications for social dominance assessment methodology, and for the issue of consensual versus ecological validity in developmental studies of social perception.     

Aggressive Behavior and Peer Social Status of Elementary School Children

The relation between aggression and peer social status was investigated in a group of 238 third-through fifth-grade children. Peer social status refers to the degree to which a child is accepted by his or her peer group. By asking children to nominate peers they “like most” and “like least,” one can identify children who are popular, rejected, neglected, or viewed as average within their peer group. Results indicated low to moderate correlations between peer-nominated aggression and global indices of social acceptance. More specifically, it was found that aggressive children largely comprised the rejected and average social status groups, but not the popular or neglected groups. Furthermore, analyses indicated that according to both peers and teachers, aggressive/rejected children showed academic and social-skill deficits, whereas aggressive children of average peer status exhibited adequate adjustment similar to that of nonaggressive/average-status children. These results suggest the importance of considering peer social status when identifying aggressive children in need of intervention and in determining which skill deficits to address. In addition, knowledge of an aggressive child's peer status might be useful in enhancing the predictability of adult adjustment.     

Gender-related assessment of childhood play

Parent-report based scales for the assessment of sex-dimorphic behavior are an important tool in research on psychosexual differentiation and its disorders. This paper presents the factor analysis and corresponding scale development for the slightly expanded Child Game Participation Questionnaire (Bates & Bentler, 1973), based on the parents of a demographically diverse school sample of 355 girls and 333 boys aged 6 to 10 years. Evidence supporting each of three theoretical positions in gender assessment — unidimensional bipolar, two-dimensional unipolar, and multidimensional — was provided. Effect sizes were unusually large for gender, but small for age, socioeconomic level, and race/ethnicity.This research was supported in part by a NICHD postdoctoral fellowship (NRSA HD06726; sponsor: Dr. Meyer-Bahlburg) awarded to Dr. Sandberg, by grants to Dr. Ehrhardt and Dr. Meyer-Bahlburg from the Spencer Foundation, the William T. Grant Foundation, the Ford Foundation, and NIMH (center grant 2-P50-MH43520, Anke A. Ehrhardt, Ph.D., Principal Investigator), and by the NIMH Clinical Research Center grant MH-30906.We thank the children and parents who participated in the study. Dr. Jacob Cohen consulted on statistical matters. Ms. Patricia Connolly provided word processing services. A portion of this work was presented as a poster at the XIth Biennial Meeting of the International Society for the Study of Behavioral Development, Minneapolis, Minnesota, July 3–7, 1991 (Abstracts, p. 285).     

Optimism and coping as determinants of psychosocial adjustment to rheumatoid arthritis

Psychosocial adjustment in 66 patients with chronic rheumatoid arthritis, with a mean duration of 12 years with the disease, were evaluated in a prospective design, with 62% of the sample followed up 16 months later. It was predicted that dispositional optimism would predict adjustment over time and that perceived support and perceived control would be related to psychosocial adjustment at the time of concurrent measurement. At Time 1, psychosocial adjustment was associated with greater optimism and perceived support and less disability. Optimism at Time 1 was the only significant predictor of changes in adjustment at Time 2 controlling for Time 1 adjustment and Time 2 disability. It was found that optimism temporally precedes increases in psychosocial adjustment. In terms of coping strategies, wishful thinking was related to poorer social adjustment, whereas problem-focused coping was marginally related to positive adjustment. Neither coping strategy predicted adjustment across time. Optimism at Time 1 did predict problem-focused coping at Time 2. Perceived social support regarding a specific circumstance at a given point in time enables one to persist in solving a task. Interventions to enhance the quality of life of individuals coping with progressive deteriorative disease must look at the influence of their behavior and attitude on those who provide care for them.     

Theory change in immunology part II: The clonal selection theory

This two-part article examines the competition between the clonal selection theory and the instructive theory of the immune response from 1957–1967. In Part I the concept of a temporally extended theory is introduced, which requires attention to the hitherto largely ignored issue of theory individuation. Factors which influence the acceptability of such an extended theory at different temporal points are also embedded in a Bayesian framework, which is shown to provide a rational account of belief change in science. In Part II these factors, as elaborated in the Bayesian framework, are applied to the case of the success of the clonal selection theory and the failure of the instructive theory.     

An alternating least squares method for the weighted approximation of a symmetric matrix

Bailey and Gower examined the least squares approximationC to a symmetric matrixB, when the squared discrepancies for diagonal elements receive specific nonunit weights. They focussed on mathematical properties of the optimalC, in constrained and unconstrained cases, rather than on how to obtainC for any givenB. In the present paper a computational solution is given for the case whereC is constrained to be positive semidefinite and of a fixed rankr or less. The solution is based on weakly constrained linear regression analysis.The authors are obliged to John C. Gower for stimulating this research.