Determining the point of subjective ambiguity of ambiguous biological-motion figures with perspective cues

Orthographic frontal/back projections of biological-motion figures are bistable: The point-light figure in principle can be perceived either as facing toward the viewer or as facing away from the viewer. Some point-light actions—for example, walking—elicit a strong “facing bias”: Despite the absence of objective cues to depth, observers tend to interpret the figure as facing toward the viewer in most of the cases. In this article, we present and experimentally validate a technique that affords full experimental control of the perceived in-depth orientation of point-light figures. We demonstrate that by parametrically manipulating the amount of perspective information in the stimulus, it is possible to obtain any desired level of subjective ambiguity. Directions for future research, in which this technique can be fruitfully implemented, are suggested. Program code of a demo is provided that can be modified easily for program code of new experiments. The demo and QuickTime movie files illustrating our perspective manipulation technique may be downloaded from http://brm.psychonomic-journals.org/ content/supplemental.     

Friend networking sites and their relationship to adolescents' well-being and social self-esteem.

The aim of this study was to investigate the consequences of friend networking sites (e.g., Friendster, MySpace) for adolescents' self-esteem and well-being. We conducted a survey among 881 adolescents (10-19-year-olds) who had an online profile on a Dutch friend networking site. Using structural equation modeling, we found that the frequency with which adolescents used the site had an indirect effect on their social self-esteem and well-being. The use of the friend networking site stimulated the number of relationships formed on the site, the frequency with which adolescents received feedback on their profiles, and the tone (i.e., positive vs. negative) of this feedback. Positive feedback on the profiles enhanced adolescents' social self-esteem and well-being, whereas negative feedback decreased their self-esteem and well-being.     

The Stereotype Threat Hypothesis: An Assessment from the Philosopher's Armchair,for the Philosopher's Classroom

According to Stereotype Threat Hypothesis (STH), fear of confirming gendered stereotypes causes women to experience anxiety in circumstances wherein their performance might potentially confirm those stereotypes, such as high‐stakes testing scenarios in science, technology, engineering, and math (STEM) courses. This anxiety causes women to underperform, which in turn causes them to withdraw from math‐intensive disciplines. STH is thought by many to account for the underrepresentation of women in STEM fields, and a growing body of evidence substantiates this hypothesis. In considering the plausibility of STH as an explanation for women's disproportionate attrition from undergraduate philosophy programs, one is struck by dissimilarities between STEM and philosophy that appear to undermine the applicability of STH to the latter. In this paper, I argue that these dissimilarities are either merely apparent or merely apparently relevant to the plausibility of STH as an explanation for gender disparities in philosophy. I argue further that, if research from STEM uncovers promising strategies for confronting stereotype threat, we should think about how to apply those strategies in our introductory philosophy classrooms.     

Precursors and Underlying Processes of Adolescents' Online Self-Disclosure: Developing and Testing an “Internet-Attribute-Perception” Model

This study developed and tested an “Internet-attribute-perception” model that explains how self-disclosure develops in instant messaging (IM) interactions. Following hyperpersonal communication theory, two attributes of computer-mediated communication (i.e., reduced nonverbal cues and controllability) were assumed to be responsible for increased online self-disclosure in IM. However, our model posed that any actual effects of these attributes would depend on users' perceptions of the relevance of these attributes. Furthermore, our model posed that these perceptions would mediate the relationship between personality characteristics (i.e., pri vate and public self-consciousness, and social anxiety) and online self-disclosure. Using structural equation modeling on a sample of 1,203 Dutch adolescents, we found that adolescents' perceptions of the relevance of reduced nonverbal cues and controllability encouraged their feelings of disinhibition, which in turn increased their online self-disclosure. As expected, private and public self-consciousness and social anxiety stimulated adolescents' perceptions of the relevance of reduced nonverbal cues and controllability, but did not directly influence online self-disclosure. The study shows the vital role of users' perceptions of CMC attributes in Internet-effects research.     

Online communication and social well‐being: how playing World of Warcraft affects players' social competence and loneliness

This study was designed to examine the effects of playing the online game World of Warcraft (WoW) on adolescents' social competence and loneliness, and to investigate the underlying mechanisms of the Internet‐affected social compensation hypothesis. The hypothesis states that being online affects adolescents' social competence as a result of a variety of communication partners and identity experiments online. A survey was conducted among 790 high school students. There appeared to be no direct effect between playing WoW and adolescents' social competence and loneliness. We did find an indirect effect via variety of communication partners. Adolescents who play WoW vary more in their communication partners, leading to an increase of social competence and a decrease of loneliness.     

Peritraumatic dissociation and posttraumatic stress after pregnancy loss: a prospective study

This study examined (1). predictors for peritraumatic dissociation, (2). its relations with acute and chronic symptoms of posttraumatic stress disorder (PTSD), and (3). pathways regarding these relations in response to pregnancy loss. In early pregnancy, about 1370 women volunteers completed questionnaires for neuroticism, control over emotions, dissociative tendencies, absorption, and prior life events. Of these, 126 subsequently experienced pregnancy loss and most of them completed measures 1 month (N = 118) and 4 months (N = 104) later. At 1 month, peritraumatic dissociation, memory of pregnancy loss (degree of fragmentation, sensory impressions, and emotional intensity), thought suppression, and PTSD symptoms were assessed, and at 4 months, PTSD symptoms were re-assessed. Peritraumatic dissociation was predicted by prior low control over emotions, dissociative tendencies, and lower education. It was not predicted by neuroticism, absorption, and prior life events. Peritraumatic dissociation was related to acute PTSD symptoms and LISREL analyses indicated that self-reported memory fragmentation and thought suppression of pregnancy loss mediated this relation. It also predicted chronic PTSD symptoms, and this relation was mediated by acute PTSD symptoms.     

Nominal scale agreement among observers

Experiments are considered where each of a sample of subjects is assigned to one of C categories separately by each of a fixed or varying group of observers. Building on earlier publications, general procedures are proposed to analyze agreements and disagreements among observers. In the case of a varying group of observers, it is shown that it is not necessary to demand a constant number of observers per subject. In the case of a fixed group of observers, the problem of missing data is considered.The procedures are illustrated within the context of two clinical diagnosis examples. In the first example it is investigated which categories are relatively hard to distinguish from one another; a new theorem is applied that shows a useful property of the statistic kappa. In the second example it is investigated if a subgroup of observers can be found with a significantly higher degree of interobserver agreement.The author gratefully acknowledges the valuable suggestions by W. Molenaar, R. van Strik, R. Popping and the referees.     

Identification and discrimination of sweep formants

Earlier identification experiments with sweep tones are repeated with rising and falling single formant (band) sweeps, with durations ranging from 15 to 40 msec and sweep rates from 0 to 40 oct/sec. Steady-state portions of 100-msec duration are then added to the sweeps. The general conclusions are that the tendency to perceive level and slightly rising tones as falling, which was such a prominent feature of the earlier results, disappears as the stimuli become more complex, and that sweep discrimination seems to be a function of the difference between the initial and the final frequency of a sweep.