The hydra-headed Mueller-Lyer effect: A theoretical puzzle

Three experiments were conducted to examine the effects of multiple fins on the magnitude of the Mueller-Lyer illusion. All studies showed that the multiple form of the elongation illusion was greater than the average of the components and that the multiple form of the shrinkage illusion was smaller than either of the components. The pattern of results failed to support either simple addition models or more complex averaging theories of illusions. A cross-attribute summation hypothesis and a filled space hypothesis were proposed as possible explanations for the results.     

MODIFICATION OF THE EXCESSIVE INAPPROPRIATE CLASSROOM BEHAVIOR OF TWO ELEMENTARY SCHOOL STUDENTS USING HOME-BASED CONSEQUENCES AND DAILY REPORT-CARD PROCEDURES1

Two experiments investigated home-based reinforcement contingencies to control excessive behavior in normal classrooms. Subjects were, respectively, a 12-yr-old fifth-grade boy and a 9-yr-old fourth-grade boy, each in a separate classroom and with a different teacher. Following baseline observations in which observers recorded several categories of student behavior and teacher-student interaction, separate conferences were held including parents of the two children, the principal, teachers, and experimenters. A daily report-card procedure was agreed on, stipulating a one-day suspension from school following three successive “undesirable” daily report cards as well as the supervision of home-based privileges and other reinforcers usually contingent on satisfactory daily reports. Measurements of daily rates of teacher attention indicated no important change in this variable throughout the various experimental conditions. The daily report procedure significantly reduced disruptive classroom behavior. In a second experiment, a teacher-operated timer cued her own time-sample observations. Reliability measures revealed that the teacher could accurately measure the child's behavior while she was teaching the class. The procedure was ultimately successfully expanded to the teacher's total contact hours each day.     

A quasi-experimental investigation of message appeal variations on organ donor registration rates.

OBJECTIVE: Approximately 6,000 Americans die every year awaiting an organ transplant. Health promotion interventions may alleviate the shortage of viable organs by increasing the number of registered organ donors. This study is the first to evaluate the differential effectiveness of various organ donor messages in naturalistic settings. DESIGN: A 4 (Appeal)x4 (Exemplar)x4 (Location) counterbalanced quasi-experimental design was implemented. MAIN OUTCOME MEASURE: The behavioral outcome measure was the number of individuals who registered to be organ donors at computer kiosks. RESULTS: A number of significant main effects and interactions emerged. Most notably, of the 4 different appeals (counterargument, emotional, motivating action, dissonance), counterargument was by far the most efficacious, especially in academic-type settings (library, university, community college); the emotional appeal was most successful in hospitals. CONCLUSIONS: The findings from this study have implications for both organ donor investigations and health campaign research in general. Statistical interactions highlight the importance of evaluating multiple exemplars in multiple locations for each type of appeal when conducting health campaign research.     

Improving Delivery Behaviors During Exposure for Pediatric OCD: A Multiple Baseline Training Trial With Community Therapists

This study tested whether a new training tool, the Exposure Guide (EG), improved in-session therapist behaviors (i.e., indicators of quality) that have been associated with youth outcomes in prior clinical trials of exposure therapy. Six therapists at a community mental health agency (CMHA) provided exposure therapy for 8 youth with obsessive–compulsive disorder (OCD). Using a nonconcurrent multiple baseline design with random assignment to baseline lengths of 6 to 16 weeks, therapists received gold-standard exposure therapy training with weekly consultation (baseline phase) followed by addition of EG training and feedback (intervention phase). The primary outcome was therapist behavior during in-session exposures, observed weekly using a validated coding system. Therapist behavior was evaluated in relation to a priori benchmarks derived from clinical trials. Additional outcomes included training feasibility/acceptability, therapist response to case vignettes and beliefs about exposure, and independent evaluator-rated clinical outcomes. Three therapists reached behavior benchmarks only during the EG (intervention) phase. Two therapists met benchmarks during the baseline phase; one of these subsequently moved away from benchmarks but met them again after starting the EG phase. Across all therapists, the percentage of weeks meeting benchmarks was significantly higher during the EG phase (86.4%) vs. the baseline phase (53.2%). Youth participants experienced significant improvement in OCD symptoms and global illness severity from pre- to posttreatment. Results provide initial evidence that adding the EG to gold-standard training can change in-session therapist behaviors in a CMHA setting.     

Interactive effects of social network centrality and social identification on stress

The present study aimed to integrate the social identity approach to health and well-being with social network analysis. Previous research on the effects of social network centrality on stress has yielded mixed results. Building on the social identity approach, we argued that these mixed results can be explained, in part, by taking into account the degree to which individuals identify with the social network. We hence hypothesized that the effects of social network centrality on stress are moderated by social identification. Using a full roster method, we assessed the social network of first-year psychology students right after the start of their study programme and three months later. The effects of network centrality (betweenness, closeness, eigenvector centrality) and social identification on stress were examined using structural equation models. As predicted, our results revealed a significant interaction between network centrality and social identification on stress: For weakly or moderately identified students, network centrality was positively related to stress. By contrast, for strongly identified students, network centrality was unrelated to stress. In conclusion, our results point to the perils of being well-connected yet not feeling like one belongs to a group.