Intruders of differing reproductive status alter aggression differentially in early and late pregnant mice

Independent groups of early and late pregnant mice, housed individually, were observed with an intruder in their home cage. The intruders were either males, virgin, early, or late pregnant females. Male intruders were sniffed less, but more frequently and more severely attacked, than any type of female intruder, both by early and by late pregnant residents. While early pregnant females behaved similarly with the three types of female intruders, late pregnant animals treated them differently: they showed practically no aggression to late pregnant intruders, more to early pregnant ones and were most aggressive towards virgin female intruders. The possible relation of these findings to reproductive behaviour is discussed.     

Enabling a man with multiple disabilities and limited motor behavior to perform a functional task with help of microswitch technology

This study evaluated the extent to which two microswitches used as interfaces would enable a man with multiple disabilities and limited motor behavior to operate an electric door opener at the entrance of the day center that he attended. Analysis showed the man (a) learned to use the two microswitches, (b) preferred the microswitch placed at his wheelchair's footrest (which also allowed more effective responding) over the microswitch placed at his wheelchair's armrest, and (c) maintained his positive performance at the 1- and 2-mo. postintervention checks. The results were discussed from a technical and practical standpoint and in terms of implications for the quality of life of persons with disabilities.     

Tendency to catastrophize somatic sensations: pain catastrophizing and anxiety sensitivity in predicting headache

General catastrophic thinking styles about uncomfortable bodily sensations may predispose the development of common health pathologies, such as persistent headache. The purpose of this research was to explore the relationships between the Pain Catastrophizing (PC) Scale and Anxiety Sensitivity (AS) Index, which measure tendencies to catastrophize pain- and anxiety-related somatic sensations, respectively. A non-clinical sample completed the PC Scale, AS Index, and health outcome questionnaires regarding headache (n = 1018). Results revealed that: (i) AS and PC are empirically separate constructs; (ii) the overlap between PC and AS lies within the domain of fearing physical catastrophe; (iii) AS independently predicts weekly headache, headache pain intensity, and the number of a wide range of physical symptoms associated with headache; and (iv) PC independently predicts the presence of weekly headache. Limitations and implications of this research, as well as recommendations for future research directions are discussed.     

The role of hyperarousal in the manifestation of posttraumatic psychological distress following injury

The authors examined the temporal relation among posttraumatic stress disorder symptom clusters, using data derived from a longitudinal study of survivors of orofacial injury (N = 264). They conducted cross-lagged panel analyses, with self-reported symptom data collected at 1, 6, and 12 months postinjury. Results demonstrate that hyperarousal was a potent predictor of subsequent symptoms of reexperiencing and avoidance as well as hyperarousal. By contrast, neither reexperiencing nor avoidance was significantly related to other symptom clusters other than themselves over time. These findings underscore the distinctive nature of hyperarousal in the manifestation of posttraumatic psychological distress over time. Implications for theory, clinical intervention, and future research are discussed.     

Aging and the role of working memory resources in visuospatial attention

Visuospatial attention has been shown to be robust to the effects of increasing age. Nonetheless, models linking individual differences in working memory capacity to attentional performance suggest that older adults may experience disruptions in visuospatial attention under conditions of resource load. Two experiments were conducted to investigate the effects of age and concurrent working memory load on two tasks that have been proposed to require posterior attentional processes. The findings suggest that loading working memory resources selectively disrupts performance on a nonintegrated Stroop task, whereas cue utilization remains intact. In addition, imposing a working memory load delays the deployment of visuospatial attention in both experiments. Regarding the effects of age, findings suggest that older adults can effectively perform both attentional tasks despite working memory load. Age differences did emerge in the time course of cue utilization. Findings point to the resilience of visuospatial attention in aging, even under conditions of significant cognitive load. We discuss these results and their implications for models postulating a role for working memory capacity in attentional behaviors.     

Gender Role Violations and Identity Misclassification: The Roles of Audience and Actor Variables

When people violate certain social role norms, they risk false categorization into a stigmatized group. For example, heterosexual men who perform female stereotypic behaviors are often misclassified as gay. This identity misclassification is aversive because it threatens fundamental psychological needs. Findings presented here reveal that expectations of identity misclassification fuel heterosexual actors’ (N?=?216) discomfort during imagined gender role violations and that audience variables that increase the likelihood of misclassification also increase role violators’ discomfort. Moreover, expectations of misclassification strongly predict people’s discomfort during gender role violations regardless of their standing along relevant actor dimensions (e.g., attitudes and self-views). These findings suggest that people’s—and particularly heterosexual men’s—expectations of identity misclassification are powerful mechanisms that underlie adherence to traditional gender role norms.     

Human and machine perception of biological motion

More than 30 years ago, Johansson was the first to show that humans are capable of recovering information about the identity and activity of animate creatures rapidly and reliably from very sparse visual inputs – the phenomenon of biological motion. He filmed human actors in a dark setting with just a few strategic points on the body marked by lights – so-called moving light displays (MLDs). Subjects viewing the MLDs reported a vivid impression of moving human forms, and were even able to tell the activity in which the perceived humans were engaged. Subsequently, the phenomenon has been widely studied and many attempts have been made to model and to understand it. Typical questions that arise are: How precisely is the sparse low-level information integrated over space and time to produce the global percept, and how important is world knowledge (e.g., about animal form, locomotion, gravity, etc.)? In an attempt to answer such questions, we have implemented a machine-perception model of biological motion. If the computational model can replicate human data then it might offer clues as to how humans achieve the task. In particular, if it can do so with no or minimal world knowledge then this knowledge cannot be essential to the perception of biological motion. To provide human data for training and against which to assess the model, an extensive psychophysical experiment was undertaken in which 93 subjects were shown 12 categories of MLDs (e.g., normal, walking backwards, inverted, random dots, etc.) and were asked to indicate the presence or absence of natural human motion. Machine perception models were then trained on normal sequences as positive data and random sequences as negative data. Two models were used: a k-nearest neighbour (k-NN) classifier as an exemplar of ‘lazy’ learning and a back-propagation neural network as an exemplar of ‘eager’ learning. We find that the k-NN classifier is better able to model the human data but it still fails to represent aspects of knowledge about body shape (especially how relative joint positions change under rotation) that appear to be important to human judgements.     

Determinants of instrumental extinction in terrestrial toads (Bufo arenarum)

Previous research in a water-reinforced instrumental training situation with toads (Bufo arenarum) has shown that performance in both acquisition and extinction is poorer after partial, rather than continuous reinforcement training. In Experiment 1, the performance of a group receiving 24 trials on a 50% partial reinforcement schedule was poorer in acquisition and extinction than that of continuously reinforced groups matched for trials or reinforcements. However, partially reinforced toads extinguished at the same rapid rate as a continuously reinforced group that received training only on the days in which the partial toads received water reinforcement. In Experiment 2, extinction was faster after 10 reinforced acquisition trials than after 30 trials. This evidence suggests that the deleterious effects of partial reinforcement in toads can be explained by a combination of two factors, namely, the distribution of reinforced trials across days and the total number of reinforcements.     

Consequences of lexical stress on learning an artificial lexicon

Four experiments examined effects of lexical stress on lexical access for recently learned words. Participants learned artificial lexicons (48 words) containing phonologically similar items and were tested on their knowledge in a 4-alternative forced-choice (4AFC) referent-selection task. Lexical stress differences did not reduce confusions between cohort items: KAdazu and kaDAzeI were confused with one another in a 4AFC task and in gaze fixations as often as BOsapeI and BOsapaI. However, lexical stress did affect the relative likelihood of stress-initial confusions when words were embedded in running nonsense speech. Words with medial stress, regardless of initial vowel quality, were more prone to confusions than words with initial stress. The authors concluded that non-initial stress, particularly when wor segmentation is difficult, may serve as "noise" that alters lexical learning and lexical access.