Biasing the pacemaker in the behavioral theory of timing

In the behavioral theory of timing, pacemaker rate is determined by overall rate of reinforcement. A two-alternative free-operant psychophysical procedure was employed to investigate whether pacemaker period was also sensitive to the differential rate of reinforcement. Responding on a left key during the first 25 s and on a right key during the second 25 s of a 50-s trial was reinforced at variable intervals, and variable-interval schedule values during the two halves of the trials were varied systematically. Responding on the right key during the first 25 s and on the left key during the second 25 s was not reinforced. Estimates of pacemaker period were derived from fits of a function predicted by the behavioral theory of timing to right-key response proportions in consecutive 5-s bins of the 50-s trial. Estimates of pacemaker period were shortest when the differential reinforcer rate most strongly favored right-key responses, and were longest when the differential reinforcer rate most strongly favored left-key responses. The results were consistent with the conclusion that pacemaker rate is influenced by relative reinforcer rate.     

Food-deprivation effects on punished schedule-induced drinking in rats.

Food-deprived rats (at 80% of their free-feeding weights) were exposed to a fixed-time 60-s schedule of food-pellet presentation and developed schedule-induced drinking. Lick-dependent signaled delays (10 s) to food presentation led to decreased drinking, which recovered when the signaled delays were discontinued. A major effect of this punishment contingency was to increase the proportion of interpellet intervals without any licks. The drinking of yoked control rats, which received food at the same times as those exposed to the signaled delay contingency (masters), was not consistently reduced. When food-deprivation level was changed to 90%, all master and yoked control rats showed decreases in punished or unpunished schedule-induced drinking. When the body weights were reduced to 70%, most master rats increased punished behavior to levels similar to those of unpunished drinking. This effect was not observed for yoked controls. Therefore, body-weight loss increased the resistance of schedule-induced drinking to reductions by punishment. Food-deprivation effects on punished schedule-induced drinking are similar to their effects on food-maintained lever pressing. This dependency of punishment on food-deprivation level supports the view that schedule-induced drinking can be modified by the same variables that affect operant behavior in general.     

Controlling the Ground Reaction Force During Lifting

The control of the ground reaction force vector relative to the center of gravity (CoG) was examined while subjects performed a back-lifting task. Six male subjects (aged 24.0 +/- 2.5 years) repeatedly lifted a barbell. A biomechanical analysis that used a linked segment model revealed that the summed rotations of body segments during lifting yielded a specific rate of change of the angular momentum of the entire body. This equaled the external moment provided by Fsubg; relative to CoG. This implies that multisegment movements involve control of the angular momentum of the entire body through an appropriately directed Fsubg;. Thus, in dynamic tasks Fsubg; is pointed away from rather than lined up with the CoG, as is the case in static tasks.     

Evaluating the Impact of a National AIDS Prevention Radio Campaign in St. Vincent and the Grenadines1

Based on extensive formative research in the three Eastern Caribbean countries of St. Lucia, St. Vincent and the Grenadines, and Grenada (Fishbein, Middlestadt, & Trafimow, 1993; Fishbein, Trafimow, et al., 1993), a three-nation, mass media, condom use campaign was developed. In order to assess the impact of the campaign, a follow-up survey was conducted in St. Vincent and the Grenadines. This paper examines the effectiveness of the campaign by comparing responses on this survey by respondents who were or were not exposed to the campaign. A statistically significant impact of exposure to the campaign was obtained, indicating that a well-designed, empirically based, mass media campaign can be an effective tool in the battle to prevent the spread of AIDS.     

A general linear model for estimating effect size in the presence of publication bias

When the process of publication favors studies with smallp-values, and hence large effect estimates, combined estimates from many studies may be biased. This paper describes a model for estimation of effect size when there is selection based on one-tailedp-values. The model employs the method of maximum likelihood in the context of a mixed (fixed and random) effects general linear model for effect sizes. It offers a test for the presence of publication bias, and corrected estimates of the parameters of the linear model for effect magnitude. The model is illustrated using a well-known data set on the benefits of psychotherapy.Authors' note: The contributions of the authors are considered equal, and the order of authorship was chosen to be reverse-alphabetical.     

The psychology of christian prayer: a review ofempirical research

This paper presents, discusses and evaluates empirical studies concerned with Christian prayer. These studies are classified within four main areas. The first area concerns what is known about the practice of prayer from empirical surveys and demonstrates that a much higher proportion of people pray privately than attend public places of worship. The second area concerns what is known about changing patterns of prayer during childhood and adolescence and argues that these changes need to be interpreted within the context of both developmental and social psychology. The third area concerns the subjective effects of prayer, beginning with Galton's early observations concerning the comparative longevity of the clergy (who are regarded as praying people) and including more recent studies of the psychological correlates of self-reported prayer, like personal well-being and purpose in life. It is concluded that, while such studies may demonstrate the beneficial nature of prayer, they cannot demonstrate the causal efficacy of prayer. The fourth area concerns the objective effects of prayer, beginning with Galton's early observations concerning the absence of comparative longevity among royalty (who are regarded as prayed for people) and including more recent studies of the growth correlates of prayer for pot plants. It is concluded that such studies currently provide contradictory evidence. It is recommended that further research in the field needs both to observe the strict criteria of objective empirical research and to be alert to theological nuances regarding the actual claims made for the efficacy of prayer within the community of believers.     

Division of labor in conversations: Are Fishman's results replicable and generalizable?

Fishman's (1978a) conclusion that women do the bulk of the support work in their conversations with male partners has had widespread appeal. In this article, we present the results of two studies designed to assess the generalizability and replicability of her findings. In Study 1. the get-acquainted conversations of 20 mixed-sex, 10 male same-sex, and 10 female same-sex dyads were analyzed for the support strategies identified by Fishman. No support for a sexual division of labor was found. In Study 2, we analyzed the casual, at-home conversations of 17 intimate male-female couples. Again, we found no evidence that the women used more of the support strategies than their male partners. Rather, our findings suggest that the women may have helped to sustain the conversations with their male partners simply by talking more. The appeal of Fishman's conclusions in the absence of empirical evidence suggests that she has touched on a mythic truth.This article is based on a Master's thesis by the second author (Study 1) and an Honour's thesis by the third author (Study 2) under the supervision of the first author.