The stimulus-response overshadowing phenomenon with VI versus FI schedules of reinforcement

Previous research has shown that response rates on a variable interval (VI) schedule of reinforcement decrease if a brief response-produced signal is given prior to reward. One explanation is that the signal overshadows the response because it is a better predictor of reinforcement. The S-R overshadowing effect does not occur with variable ratio (VR) schedules, however. Tarpy, Lea, and Midgley (1983) explained this fact by suggesting that the signal functions to enhance the salience of the temporal interval offset on the VI schedule (a characteristic not possessed by VR schedules), which then overshadows the response. In this experiment, the salience of the temporal interval was enhanced in another way: signaled or unsignaled reward was provided to rats responding on either a VI or fixed interval (FI) reward schedule. As predicted, rates were lowest for animals receiving signaled reinforcement on an FI schedule and highest for those receiving unsignaled reinforcement on a VI schedule.     

Internalizing symptoms and affect of children with emotional and behavioral disorders: A comparative study with an urban African American sample

Self‐reported internalizing symptoms of seriously emotionally disturbed (SED) and regular education students in grades 4–6 were compared using the Internalizing Symptoms Scale for Children. All participants were African American and from an urban public school district in the Southeastern United States. Each of the two study groups consisted of 50 participants (35 boys, 15 girls) who were matched by gender and socioeconomic status. The SED group reported significantly higher levels of internalizing distress than the regular education group. In contrast to previous findings, there was no significant gender difference in self‐reported internalizing symptomatology in the present study. A discriminant function analysis found that the ISSC scores were able to correctly classify 91% of the participants into their respective educational group. Results of this study provide additional evidence of the construct validity of the ISSC, a recently developed and unique self‐report measure. Results are discussed in terms of future research needs and educational/clinical practice with students who have emotional and behavioral disorders. © 1999 John Wiley & Sons, Inc.     

There’s something about Mary: The moral value of things <Emphasis Type="Italic">qua</Emphasis> information objects

Luciano Floridi argues that every existing entity is deserving of at least minimal moral respect in virtue of having intrinsic value qua information object. In this essay, I attempt a comprehensive assessment of this important view as well as the arguments Floridi offers in support of it. I conclude both that the arguments are insufficient and that the thesis itself is substantively implausible from the standpoint of ordinary intuitions.     

A study of color in dissertations and theses

This study examined the occurrence of color in dissertations and theses produced at the Pennsylvania State University over a nine year period. Since the most common preservation method for dissertations and theses is monochromatic microfilming, traditional treatment may result in a loss of information encoded in color in these resources. Results indicate a significant increase in the use of color over the time period studied. Variations in the amount of color use by discipline were also observed. Implications related to monochromatic microfilming and recommendations for long term preservation are discussed.     

Bibliographic control of medical illustrations--a case study in the development of a library subsystem: I. Project planning

The need to provide bibliographic access to a collection of original medical illustrations led the Library of the University of California, San Francisco, to search for a bibliographic control system and, not finding a satisfactory one, to develop one of its own, Part 1 of the report details the planning for such a development, including the need for bibliographic control of illustrations, the goals of the proposed system, design decisions and changes required, the type of system chosen, special subjects indexing needs, the required output, and staffing and budgetary needs.     

Not virtual,but a real,live, online,interactive reference service

In today's fast-paced environment, traditional medical reference services alone are not adequate to meet users' information needs. Efforts to find new ways to provide comprehensive service to users, where and when needed, have often included the use of new and developing technologies. This paper describes the experience of an academic health science library in developing and providing an online, real-time reference service. Issues discussed include selecting software, training librarians, staffing the service, and considering the future of the service. Use statistics, question type analysis, and feedback from users of the service and librarians who staff the service, are also presented.     

Movement and stretching imagery during flexibility training

Abstract

The aim of this study was to examine the effect of movement and stretching imagery on increases in flexibility. Thirty volunteers took part in a 4 week flexibility training programme. They were randomly assigned to one of three groups: (1) movement imagery, where participants imagined moving the limb they were stretching; (2) stretching imagery, where participants imagined the physiological processes involved in stretching the muscle; and (3) control, where participants did not engage in mental imagery. Active and passive range of motion around the hip was assessed before and after the programme. Participants provided specific ratings of vividness and comfort throughout the programme. Results showed significant increases in flexibility over time, but no differences between the three groups. A significant relationship was found, however, between improved flexibility and vividness ratings in the movement imagery group. Furthermore, both imagery groups scored significantly higher than the control group on levels of comfort, with the movement imagery group also scoring significantly higher than the stretching imagery group. We conclude that the imagery had stronger psychological than physiological effects, but that there is potential for enhancing physiological effects by maximizing imagery vividness, particularly for movement imagery.