Hubert's multi-rater kappa revisited

There is a frequent need to measure the degree of agreement among R observers who independently classify n subjects within K nominal or ordinal categories. The most popular methods are usually kappa-type measurements. When R = 2, Cohen's kappa coefficient (weighted or not) is well known. When defined in the ordinal case while assuming quadratic weights, Cohen's kappa has the advantage of coinciding with the intraclass and concordance correlation coefficients. When R > 2, there are more discrepancies because the definition of the kappa coefficient depends on how the phrase ‘an agreement has occurred’ is interpreted. In this paper, Hubert's interpretation, that ‘an agreement occurs if and only if all raters agree on the categorization of an object’, is used, which leads to Hubert's (nominal) and Schuster and Smith's (ordinal) kappa coefficients. Formulae for the large-sample variances for the estimators of all these coefficients are given, allowing the latter to illustrate the different ways of carrying out inference and, with the use of simulation, to select the optimal procedure. In addition, it is shown that Schuster and Smith's kappa coefficient coincides with the intraclass and concordance correlation coefficients if the first coefficient is also defined assuming quadratic weights.     

Age influences domestic dog cognitive performance independent of average breed lifespan

Animal Cognition - Across mammals, increased body size is positively associated with lifespan. However, within species, this relationship is inverted. This is well illustrated in dogs (Canis...     

Behavioral anatomy of a hunt

It is commonly thought that the mind constructs predictive models of the environment to plan an appropriate behavioral response. Therefore a more predictable environment should entail better performance, and prey should move in an unpredictable (random) manner to evade capture, known as protean motion. To test this, we created a novel experimental design and analysis in which human participants took the role of predator or prey. The predator was set the task of capturing the prey, while the prey was set the task of escaping. Participants performed this task standing on separate sides of a board and controlling a marker representing them. In three conditions, the prey followed a pattern of movement with varying predictability (predictable, semi-random, and random) and in one condition moved autonomously (user generated). The user-generated condition illustrated a naturalistic, dynamic environment involving a purposeful agent whose degree of predictability was not known in advance. The average distance between participants was measured through a video analysis custom-built in MATLAB. The user-generated condition had the largest average distance. This indicated that, rather than moving randomly (protean motion), humans may naturally employ a cybernetic escape strategy that dynamically maximizes perceived distance, regardless of the predictability of this strategy.

     

Exploring Wellbeing in Youth with Vision Impairment: Insights for Vision Rehabilitation

Applied Research in Quality of Life - This article explores the discussions of 21 young Australians (aged 12–25) with vision impairment regarding their lived experiences and what it meant for...     

Do we access meaning when we name Arabic digits? Electrophysiological evidence

In this study, we evaluated whether the naming of Arabic digits required access to semantic information. Participants named pictures and Arabic digits blocked by category or intermixed with exemplars of other categories while behavioural and electrophysiological measures were gathered. Pictures were named slower and Arabic digits faster in the blocked context relative to the mixed context. Around 350–450 ms after the presentation of pictures and Arabic digits, brain waves were more positive in anterior regions and more negative in posterior regions when the blocked context was compared with the mixed context. The pattern of electrophysiological results suggests that pictures and Arabic digits are both processed semantically and they are subject to repetition effects during the naming task.     

The fit and implementation of sexual harassment law to workplace evaluations

Three studies used videotaped harassment complaints to examine the impact of legal standards on the evaluation of social-sexual conduct at work. Study 1 demonstrated that without legal instructions, college students' judgment strategies were highly variable. Study 2 compared 2 current legal standards, the "severity or pervasiveness test" and a proposed utilitarian alternative (i.e., the rational woman approach). Undergraduate participants taking the perspective of the complainant were more sensitive to offensive conduct than were those adopting an objective perspective. Although the utilitarian altemative further increased sensitivity on some measures, it failed to produce a principled judgment strategy. Finally, Study 3 examined the kinds of errors that full-time workers make when applying the "severity or pervasiveness" test to examine more closely the sensitivity of the subjective approach.     

Sex differences and estropausal phase effects on water maze performance in aged rats

An age-related decline in memory has been reported in male rats; however, there are few studies that have addressed these changes in aged female rats. In young female rats, hormonal cycles influence behavior. By the age of 22 months most female rats have not had regular hormonal cycles for at least 9 months. In the current study we examined how the hormonal status (persistent estrus and pseudo-pregnant) of the aged (22-24 months) female rat (Long Evans) influenced performance on a spatial version of the Morris water maze and compared this to aged male rats. Aged females in persistent estrus showed better performance on the water maze than both aged females that were pseudopregnant and aged males. Thus, postestropausal hormonal status may influence the course of aging in females.