The size-constancy of underwater swimmers

The size-constancy of divers was measured by requiring them to adjust the distance between two disks of unequal size so that they appeared phenomenally equal. In clear water divers showed greater constancy-ratios than on land. In murky water, where visibility was reduced by suspended particles, constancy-ratios were the same as, or less than, on land. It is suggested that these effects may be due to changes in apparent distance: in clear water objects appear nearer through refraction, but in murky water they appear further away because of the distance cues provided by the visibility gradient.

The orientation of the display, or of the diver's body, did not affect constancy under water, though it does on land. It is argued that the effect on land is due to visual and proprioceptive cues which are absent in the water.     

Some Effects of Reduction of Extra-Classroom Crowding in a School Environment

The effects of reduced enrollment were studied by examining two architecturally identical schools. One school experienced a 43% reduction in enrollment while the other's enrollment remained constant. Reduction in enrollment had a number of positive benefits, including improved attitudes about the school environment and reduced faculty absenteeism. Findings regarding academic performance were less clear.     

Dynamic changes in work/rest duty cycles in a study of sleep deprivation

The effects of moderate workload and 72 h of sleep deprivation were studied using a modified continuous-performance paradigm. Ten subjects were tested hourly on a number of perceptual and cognitive tasks designed to require approximately 30 min to complete, with the remainder of each hour free. As sleep deprivation continued, the average time on task increased at an accelerating rate. The rate of increase differed among tasks, with longer tasks showing greater absolute and relative increases than shorter ones. Such increases confound sleep deprivation and workload effects. In this paper, we compare the advantages and disadvantages of several experimental paradigms; describe details of the present design; and discuss methodological problems associated with separating the interactions of sleep deprivation, workload, and circadian variation with performance.     

Bayesian inference for psychology. Part II: Example applications with JASP

Bayesian hypothesis testing presents an attractive alternative to p value hypothesis testing. Part I of this series outlined several advantages of Bayesian hypothesis testing, including the ability to quantify evidence and the ability to monitor and update this evidence as data come in, without the need to know the intention with which the data were collected. Despite these and other practical advantages, Bayesian hypothesis tests are still reported relatively rarely. An important impediment to the widespread adoption of Bayesian tests is arguably the lack of user-friendly software for the run-of-the-mill statistical problems that confront psychologists for the analysis of almost every experiment: the t-test, ANOVA, correlation, regression, and contingency tables. In Part II of this series we introduce JASP (http://www.jasp-stats.org), an open-source, cross-platform, user-friendly graphical software package that allows users to carry out Bayesian hypothesis tests for standard statistical problems. JASP is based in part on the Bayesian analyses implemented in Morey and Rouder’s BayesFactor package for R. Armed with JASP, the practical advantages of Bayesian hypothesis testing are only a mouse click away.     

A case-controlled field study evaluating ICD-11 proposals for relational problems and intimate partner violence

Background/Objective: Intimate partner relationship problems and intimate partner abuse and neglect — referred to in this paper as “relational problems and maltreatment” — have substantial and well-documented impact on both physical and mental health. However, classification guidelines, such as those found in the International Classification of Diseases (ICD-10), are vague and unlikely to support consistent application. Revised guidelines proposed for ICD-11 are much more operationalized. We used standardized clinical vignette conditions with an international panel of clinicians to test if ICD-11 changes resulted in improved classification accuracy. Method: English-speaking mental health professionals (N = 738) from 65 nations applied ICD-10 or ICD-11 (proposed) guidelines with experimentally manipulated case presentations of presence or absence of (a) individual mental health diagnoses and (b) relational problems or maltreatment. Results: ICD-11, compared with ICD-10, guidelines resulted in significantly better classification accuracy, although only in the presence of co-morbid mental health problems. Clinician factors (e. g., gender, language, world region) largely did not impact classification performance. Conclusions: Despite being considerably more explicated, raters’ performance with ICD-11 guidelines reveals training issues that should be addressed prior to the release of ICD-11 in 2018 (e. g., overriding the guidelines with pre-existing archetypes for relationship problems and physical and psychological abuse).