Towards a mathematical model of within-session operant responding

Operant response rate changes within the course of a typical free-operant experimental session. These changes are orderly, and reliably demonstrated with subjects from different species, responding under different experimental conditions. Killeen (1995) postulated that the response rate changes are a function of the interplay between arousal and satiation and offered a mathematical model for this hypothesis. Here we analyze Killeen's model, demonstrating that, although solid in its principles, it presents some flaws in its implementation. Then, based on the same principles, we build and test a new model of within-session motivation dynamics. We also demonstrate that, by representing arousal as a variable that ranges between 0 and 1, we can obtain a surprisingly simple model of free-operant response rate.     

Aggression is suppressed by acute stress but induced by chronic stress: Immobilization effects on aggression, hormones, and cortical 5-HT1B/ striatal dopamine D2 receptor density

Although it has been established by a number of investigators that a variety of stressors are associated with the induction of aggressive behavior, two specific issues remain unanswered. First, it is unclear whether the contexts surrounding stressors (e.g., stressor length and chance of winning over opponents) change outcomes regarding aggressive behavior. Second, if a relationship exists between stress and aggressive behavior, altered levels of stress-related hormone (e.g., corticosterone [CORT]), as well as aggression-related biomarkers (e.g., testosterone [T], density of prefronto-cortical 5-HT(1B) receptor and striatal dopamine D(2) receptor [D2r]) may contribute to changes in aggressive behavior. Thus, we examined how immobilization (with a 1-, 5-, or 10-day exposure) would impact (1) a longitudinal course of aggression toward different-sized opponents, (2) levels of CORT and T, and (3) densities of 5-HT(1B) receptor (5-HT1Br) in the prefrontal cortex (PFC) and D2r in the striatum. It was found that, regardless of small or large opponents, a single 2-h exposure to immobilization reduced aggressive behavior (stress-suppressed aggression) over time, whereas repeated (10-day) exposure to immobilization escalated aggressive behavior (stress-induced aggression). These stress effects persisted up to 1 week of recovery from immobilization stress. Moreover, immobilized rats demonstrated elevated levels of T, but not CORT, as compared with controls. Finally, acute immobilization altered D2r densities in the shell of the nucleus accumbens, and chronic immobilization changed 5-HT1Br in the PFC, including the downregulation of 5-HT1Br densities in the right prelimbic and orbitolateral cortices. The potential relationships among stress, aggression, and 5-HT1Br/D2r roles are discussed.     

Non-bayesian inference: causal structure trumps correlation

The study tests the hypothesis that conditional probability judgments can be influenced by causal links between the target event and the evidence even when the statistical relations among variables are held constant. Three experiments varied the causal structure relating three variables and found that (a) the target event was perceived as more probable when it was linked to evidence by a causal chain than when both variables shared a common cause; (b) predictive chains in which evidence is a cause of the hypothesis gave rise to higher judgments than diagnostic chains in which evidence is an effect of the hypothesis; and (c) direct chains gave rise to higher judgments than indirect chains. A Bayesian learning model was applied to our data but failed to explain them. An explanation-based hypothesis stating that statistical information will affect judgments only to the extent that it changes beliefs about causal structure is consistent with the results.     

Exploring the Construct of Perceived Burdensomeness Among Suicidal Adolescents: An Intervention Development Study

Journal of Child and Family Studies - The Interpersonal Psychological Theory of Suicide has a growing base of empirical support for use with adolescents. Of the two interpersonal constructs that...     

Women and body dissatisfaction: Does sexual orientation make a difference?

In this study, heterosexual (n = 95) and nonheterosexual (n = 84) women were asked to rate figure drawings and computer-generated images of women that varied in body fat, waist-to-hip ratio, and breast size in terms of self, ideal, and cultural ideal; discrepancy indices, indicating body dissatisfaction, were created for each body aspect. Nonheterosexual women had significantly higher body mass indices (BMIs) than heterosexual women, but when the effects of BMI were controlled, participants evidenced similar perceptions of their bodies, their ideal bodies, and the female cultural ideal, as well as similar levels of body dissatisfaction for body fat, waist-to-hip ratio, and breast size. The results of this study suggest that being a member of a society that highly values a thin, curvaceous, relatively large-breasted body puts women, regardless of sexual orientation, at risk for body dissatisfaction.     

Fostering connections between graduate students and strengthening professional identity through co-mentoring

For counsellors and counsellor educators, developing a sound sense of professional identity is a necessity in preserving and advancing the counselling field. In an effort to promote professional identity development in a group of counsellors in training, a co-mentoring programme was developed that paired master's level and doctoral level counsellors. The participants used letter writing and email to support the development of these mentoring relationships over the course of a semester. This study attempted to measure the effectiveness of the co-mentoring programme using interview data and written artefacts. An open, axial and selective coding process was employed. The participants of the study identified themes of enhanced professional identity development and collegial professional relationships as a result of participating in the co-mentoring relationship. Further research is needed to determine how best to support professional identity development for emerging professionals and the effectiveness of mentoring relationships and letter writing in this developmental process. A co-mentoring programme may offer training settings an opportunity for student self-awareness and growth in an experiential and meaningful manner, as well as providing additional opportunities for students to develop their professional identity. Implications for the use of co-mentoring and mentoring programmes to aid in the identity development of counsellors or other professionals are addressed.     

An Evaluation of Alternative Ways of Computing the Creativity Quotient in a Design School Sample

Certain educational programs and jobs require selecting individuals based on their creativity. Tests of creativity are commonly based on divergent thinking tasks. The scoring of the ideational output of such tasks should ideally be done based on fluency (the number of ideas generated), flexibility (the number of categories into which the generated ideas can be partitioned), and originality (the number of unique or unusual ideas). However, most scoring procedures do not take into account all three dimensions. Building on the Creativity Quotient (CQ) measure (Snyder, Mitchell, Bossomaier & Pallier, 2004 Snyder , A. , Mitchell , J. , Bossomaier , T. , & Pallier , G. ( 2004 ). The creativity quotient: An objective scoring of ideational fluency . Creativity Research Journal , 16 , 415 – 420 .[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]), which covers fluency and flexibility, an adjusted CQ and two CQs based on diversity type measures are proposed. Findings indicated that an adjusted measure that weights categories based on their discriminative power was most strongly related to other predictors of performance on creative tasks and thus presents an important advance over the original CQ.     

Cognitive Load and Prism Adaptation

Subjects wore goggles with prisms that laterally displaced the visual field (rightward by 11.4°) and with full view of the limb engaged in paced (2-s rate) sagittal pointing at either an implicit (“straight ahead of the nose”) target (Experiment 1) or an explicit (positioned leftward by 11.4°) target (in Experiment 2). In experimental conditions, subjects performed a secondary cognitive task (mental arithmetic) simultaneously during target pointing. In control conditions, no cognitive load was imposed. Aftereffect measures of adaptation to the prismatic displacement were not substantially different when problem solving was required, but terminal error of the exposure pointing task was reliably affected by cognitive load. These results are consistent with the hypothesis of separable mechanisms for adaptive coordination and adaptive alignment. Adaptive coordination may be mediated by strategically flexible coordinative linkage between sensory–motor systems (eye–head and hand—head), but spatial alignment seems to be mediated by adaptive encoders within coordinatively linked subsystems. If the coordination task involves predominately automatic processing, coordinative linkage can be frequent enough under cognitive load for substantial realignment to occur even though exposure performance (adaptive coordination) may be less than optimal.     

Where does work stress come from? A generalizability analysis of stress in police officers

Differences among workers and workplace stressors both contribute to perceiving work as stressful. However, the relative importance of these sources to work stress is not well delineated. Moreover, the extent to which work stress additionally reflects unique matches between specific workers and particular job stressors is also unclear. In this study, we use generalizability theory to specify and compare sources of variance in stress associated with police work. US police officers (N?=?115) provided ratings of 60 stressors commonly associated with policing duties. Primary and secondary stress appraisal ratings reflected differences among officers in tendencies to generally perceive work stressors as stressful (14–15% officer effect), and also agreement among officers in viewing some stressors as more stressful than others (18–19% stressor effect). However, ratings especially reflected distinct pairings of officers and stressors (38–41% interaction effect). Additional analyses revealed individual differences and stressor characteristics associated with each variance component, including an officer?×?stressor interaction – compared to officers low in neuroticism, highly neurotic officers provided lower primary appraisal ratings of stressors generally seen as not serious, and also higher primary appraisal ratings of stressors that were seen as serious. We discuss implications of the current approach for the continued study of stress at work.     

Psychodiagnostic Evaluation of Johnny

Rabin, A. I., Growing up in the Kibbutz, New York; Springer Publishing Company. 1965. 230 pp. Reviewed by Haim G. Ginott