How reinforcement context affects temporal production and categorization

The behavioral theory of timing assumes that timing is governed by a pacemaker whose pulses move organisms from one state to the next, and that the speed of the pacemaker covaries with the rate of reinforcement in the experimental context. The goal of the present experiments was to clarify just what constitutes that context. In Experiment 1, pigeons responded on signaled fixed-interval 20-sec and 40-sec schedules of food reinforcement that were presented randomly within sessions (alternating condition) or between sessions (isolated condition). In Experiment 2, pigeons categorized the duration of a short or a long set of intervals in the alternating or the isolated condition. Performance in both experiments was under strong control by the signals, with scalar timing between long and short sets, but no significant differences between the alternating and isolated conditions. The context of reinforcement that determines pacemaker period can thus be specific to a particular timing task and signal.     

Seeking for the unwelcome truths: beyond celebration in inquiry-based teacher professional learning

This paper seeks to interrupt the dominant discourse of action research that emphasises the celebration of achievements, paying less attention to the ‘unwelcome truths’ that can sometimes be revealed. Building on our work in supporting inservice teacher professional learning thorough practitioner research in contexts such as the Coalition of Knowledge Building Schools, we examine the capacity of practitioner inquiry and student voice to contribute to teachers’ broader professional knowledge base. Welcoming ‘unwelcome truths’ requires a robustness on the part of teachers, an openness to the professional learning and growth that can ensue from genuine critique and reflection. Among other things, asking questions of young people in schools can sometimes yield new and challenging insights into school and learning. We draw on examples from our work with schools and teachers to consider what might be done to make these ‘unwelcome truths’ the basis for the reconceptualisation of practice and catalysts for the ongoing formation of teacher professional identity.     

Not all school dropouts are the same: Ethnic differences in the relation between reason for leaving school and adolescent substance use

Several national studies have revealed that students choose to drop out of school for a variety of reasons. Moreover, there are ethnic differences in the reasons dropouts give for leaving school. In the present study, the relation between reason for dropping out and substance use was explored in Mexican American and non‐Hispanic White adolescents. The results revealed that for Mexican American adolescents, substance use was highest among those who left school to be with their friends and lowest among those who left for family‐related reasons. Among non‐Hispanic White adolescents, there were no significant differences in substance use as a function of reason for leaving school. For both ethnicities, nearly one‐third of the dropouts reported that their substance use was an important contributor to their decision to leave school early. The theoretical and practical implications of these findings are discussed. Recommendations are made for ways in which the reasons that dropouts give for leaving school can be used to inform school programs. © 2002 John Wiley & Sons.     

The MEDLARS project at the UCLA Biomedical Library

The National Library of Medicine has established at the Biomedical Library, UCLA, a remote MEDLARS search station. The agreement between the libraries provided that the Biomedical Library in cooperation with the UCLA Health Sciences Computing Facility would reprogram MEDLARS for the IBM 7094 computer, provide personnel to be trained in machine searching at NLM, and engage in a pilot demonstration of search service to the medical staff of UCLA. This paper describes the place of the search section in the organization of the Biomedical Library and the training of personnel at NLM (the article by Garvis in this issue of the Bulletin relates the problems encountered in making two different computer systems compatible). Search service had not begun when this paper was written; it was scheduled to begin late in 1965. Plans for the future include the enlargement of the UCLA MEDLARS staff and extension of search service to a larger geographical area.     

Bridging scientific reasoning and conceptual change through adaptive web‐based learning

This study reports an adaptive digital learning project, Scientific Concept Construction and Reconstruction (SCCR), and examines its effects on 108 8th grade students' scientific reasoning and conceptual change through mixed methods. A one‐group pre‐, post‐, and retention quasi‐experimental design was used in the study. All students received tests for Atomic Achievement, Scientific Reasoning, and Atomic Dependent Reasoning before, 1 week after, and 8 weeks after learning. A total of 18 students, six from each class, were each interviewed for 1 hour before, immediately after, and 2 months after learning. A flow map was used to provide a sequential representation of the flow of students' scientific narrative elicited from the interviews, and to further analyze the level of scientific reasoning and conceptual change. Results show students' concepts of atoms, scientific reasoning, and conceptual change made progress, which is consistent with the interviewing results regarding the level of scientific reasoning and quantity of conceptual change. This study demonstrated that students' conceptual change and scientific reasoning could be improved through the SCCR learning project. Moreover, regression results indicated students' scientific reasoning contributed more to their conceptual change than to the concepts students held immediately after learning. It implies that scientific reasoning was pivotal for conceptual change and prompted students to make associations among new mental sets and existing hierarchical structure‐based memory. © 2009 Wiley Periodicals, Inc. J Res Sci Teach 47: 91–119, 2010     

Preparing pre‐service teachers for inclusive classrooms: revising lesson‐planning expectations

The purpose of this article is to explore the use of a lesson‐planning template designed to support and scaffold pre‐service teachers’ lesson‐planning techniques for a wide range of learners in inclusive classrooms. This template is currently used across the final three semesters of a dual certification inclusive elementary and special education teacher preparation programme. This article reports on an empirical study using a mixed methodology that addresses the following question: How do pre‐service teachers, university faculty, supervising teachers and field supervisors perceive their experiences using this template? Addressing that question led to revising the original template. This article concludes with that revised lesson‐planning template.     

Sexual Socialization Messages in Television Programming Produced for Adolescents

This study examined sexual content in American prime-time programs popular among the tween (9–14 years of age) audience on broadcast networks and programs aired on the most popular adolescent TV networks—an understudied area of media research. Consistent with past research, the majority of broadcast shows contained sexual talk and behaviors, as did adolescent shows. No significant difference was observed between the two types of shows regarding the frequency with which sexual behaviors were presented in a given hour of TV programming. The amount of scene focus paid to sexual themes varied, but studio audiences were almost always heard positively reinforcing these messages. The findings are discussed with respect to social cognitive and cultivation theories.     

A Six‐Year Longitudinal Study of Texting Trajectories During Adolescence

This study examined growth trajectories of texting (and other media) over a 6‐year time period. Participants were 425 adolescents from Washington, USA (age 13 at Time 1, age 18 at Time 6; 48% male, 68% European American). Analyses suggested a curvilinear pattern for texting and social media use, with rates peaking during midadolescence. There was also considerable heterogeneity in trajectories of texting. A growth mixture model revealed four distinct classes of individuals: perpetuals (14%), decreasers (7%), moderates (68%), and increasers (11%). Higher levels of depression, being a male, and coming from a single‐parent family predicted being a “perpetual” texter. Perpetuals had the most problematic outcomes compared to other classes, including higher depression, anxiety, aggression, and poor relationships with fathers.