The effect of task structure on diffusion dynamics: Implications for diffusion curve and network-based analyses

Theoretical analyses within the broad field of social learning research give mixed conclusions on whether the shape of a diffusion curve can be used to infer that a learned trait increases through social or asocial learning. Here we explore how factors such as task structure (e.g., multiple-step tasks), task abandonment, subgoal learning, and neophobia affect the shape of the diffusion curve for both asocially learned and socially learned behavior. We demonstrate that, whereas social learning increases the likelihood of S-shaped curves, sigmoidal patterns can be generated by entirely asocial processes, and cannot be reliably interpreted as indicators of social learning. Our findings reinforce the view that diffusion curve analysis is not a reliable way of detecting social transmission. We also draw attention to the fact that task structure can similarly confound interpretation of network-based diffusion analyses, and suggest resolutions to this problem. Supplemental materials for this article may be downloaded from http://lb.psychonomic-journals.org/content/supplemental.     

束手无策?回归初心

"初学者的思维饱含可能,久习者的思维饱受羁绊。"——禅修大师铃木俊隆多年前,我还是一个瑜伽学生时,就在想象教授瑜伽会是件多么美妙的事。作为一个初学者,我总能接受新思想:我开始对瑜伽练习产生了狂热的兴趣,我就     

Variability and progression in competitive performance of Paralympic swimmers

Abstract

Analysis of variability and progression in performance of top athletes between competitions provides information about performance targets that is useful for athletes, practitioners, and researchers. In this study, 724 official finals times were analysed for 120 male and 122 female Paralympic swimmers in the 100-m freestyle event at 15 national and international competitions between 2004 and 2006. Separate analyses were performed for males and females in each of four Paralympic subgroups: S2–S4, S5–S7, S8–S10 (most through least physically impaired), and S11–S13 (most through least visually impaired). Mixed modelling of log-transformed times, with adjustment for mean competition times, was used to estimate variability and progression. Within-swimmer race-to-race variability, expressed as a coefficient of variation, ranged from 1.2% (male S5–S7) to 3.7% (male S2–S4). Swimming performance progressed by approximately 0.5% per year for males and females. Typical variation in mean performance time between competitions was ～1% after adjustment for the ability of the athletes in each competition, and the Paralympic Games was the fastest competition. Thus, taking into account variability, progression, and level of competition, Paralympic swimmers who want to increase substantially their medal prospects should aim for an annual improvement of at least 1–2%.     

The validity and utility of the California Family Risk Assessment under practice conditions in the field: A prospective study

Objective

Analysis of the validity and implementation of a child maltreatment actuarial risk assessment model, the California Family Risk Assessment (CFRA).

Questions addressed

(1) Is there evidence of the validity of the CFRA under field operating conditions? (2) Do actuarial risk assessment results influence child welfare workers’ service delivery decisions? (3) How frequently are CFRA risk scores overridden by child welfare workers? (4) Is there any difference in the predictive validity of CFRA risk assessments and clinical risk assessments by child welfare workers?

Method

The study analyzes 7,685 child abuse/neglect reports originating in 5 California counties followed prospectively for 2 years to identify further substantiated child abuse/neglect. Measures of model calibration and discrimination were used to assess CFRA validity and compare its accuracy with the accuracy of clinical predictions made by child welfare workers. The extent of use of an override feature of the CFRA and child welfare worker reliance on CFRA risk scores for making service decisions were analyzed.

Results

Imperfect but better-than-chance predictive validity was found for the CFRA on a range of measures in a large temporal validation sample (n = 6,543). For 114 cases where both CFRA risk assessments and child welfare worker clinical risk assessments were available, the CFRA exhibited evidence of imperfect but better-than-chance predictive validity, while child welfare worker risk assessments were found to be invalid. Child welfare workers overrode CFRA risk assessments in only 114 (1.5%) of 7,685 cases and provided in-home services in statistically significantly larger proportions of higher- versus lower-risk cases, consistent with heavy reliance on the CFRA.

Conclusions/practice implications

Until research identifies actuarial models exhibiting superior predictive validity when applied in every-day practice, the CFRA is, and will be a valuable tool for assessing risk in order to make in-home service-provision decisions.     

The role of student academic beliefs in perceptions of instructor ideological bias

A common perception exists in the media that university instructors are a liberal elite who use their positions to instill a biased perspective in their students. Exploring student attitudes in the United States and Australia, the present study examined how students’ academic beliefs are related to their inferences of instructor ideological bias and the degree to which they identify as reacting to these inferences in the college classroom. Results of regression analysis using previously validated survey instruments revealed that students’ academic entitlement and grade orientation (GO) predicted perceptions of instructor bias. In addition, students’ GO predicted students’ reactions to such inferred bias. Institutional differences, pedagogical implications, and areas for future research are discussed.     

Easton Cowboys and Cowgirls: a ‘political’ sports club that is not political and ‘anarchist’ sports club that is not actually anarchist

In this paper I offer an activist's own account of a grass-roots club I helped found in 1992 and I remain an active member of today. The Easton Cowboys and Cowgirls are an amateur sports club based in inner-city Bristol. We have not got our own ground and most people would not have heard of us. We play at the very lowest rung of UK mass participation sport – in the Sundays and Saturday leagues, on the muddy pitches and municipal sports grounds where week after week men and women run around, for their own enjoyment without expectation of financial gain of any sort. My aim is to explain why the Cowboys and Cowgirls are an extraordinary club, outlining some of the extraordinary things it has done, some of which reside beyond the imagination of most professional clubs. It is only now, 20 years after we first formed, that we can stand back and admire what we have achieved and appreciate the role we have played in developing a small but growing network of teams that stand at odds with the way society is organized and (to a certain extent) the mediated, poisoned world of professional sport.