Intermittent exposure to social defeat and open-field test in rats: acute and long-term effects on ECG,body temperature and physical activity

This study investigated the effects of exposure to an intermittent homotypic stressor on: (i) habituation of acute autonomic responsivity (i.e. cardiac sympathovagal balance and susceptibility to arrhythmias), and (ii) circadian rhythmicity of heart rate, body temperature, and physical activity. After implantation of a transmitter for the radiotelemetric recording of electrocardiogram (ECG), body temperature and physical activity, adult male rats (Rattus norvegicus, Wild Type Groningen strain) were repeatedly exposed (10 consecutive times, on alternate days) to either a social stressor (defeat by a con-specific, n = 15) or an open-field, control challenge (transfer to a new cage; n = 8). ECGs, body temperature and physical activity were continuously recorded in baseline, test and recovery periods (each lasting 15 min), at the 1st and 10th episodes of both defeat and open-field challenge. The circadian rhythms of heart rate, body temperature and physical activity were monitored before (5 days), during (16 days) and after (21 days) the intermittent stress protocol. This study indicates that there is no clear habituation of either acute cardiac autonomic responsivity (as estimated by means of time-domain indexes of heart rate variability) or arrhythmia occurrence to a brief, intermittent, homotypic challenge, regardless of the nature of the stressor (social or non-social). On the other hand, rats exposed to social challenge also failed to show adaptation of acute temperature and activity stress responsiveness, whereas rats facing open-field challenge developed habituation of activity and sensitization of temperature responses. Repeated social challenge produced remarkable reductions of the heart rate circadian rhythm amplitude (this effect being significantly greater than that produced by intermittent open-field), but only minor changes in the daily rhythms of body temperature and physical activity.     

When are puppies receptive to emotion-induced human chemosignals? The cases of fear and happiness

Animal Cognition - We report an observational, double-blind, experimental study that examines the effects of human emotional odors on puppies between 3 and 6 months and adult dogs...     

HOPOS 2000. Call for Papers. THIRD INTERNATIONAL HISTORY OF PHILOSOPHY OF SCIENCE CONFERENCE

Call for Papers

HOPOS 2000. Call for Papers. THIRD INTERNATIONAL HISTORY OF PHILOSOPHY OF SCIENCE CONFERENCE     

Prove it! The Burden of Proof Game in Science vs. Pseudoscience Disputes

The concept of burden of proof is used in a wide range of discourses, from philosophy to law, science, skepticism, and even in everyday reasoning. This paper provides an analysis of the proper deployment of burden of proof, focusing in particular on skeptical discussions of pseudoscience and the paranormal, where burden of proof assignments are most poignant and relatively clear-cut. We argue that burden of proof is often misapplied or used as a mere rhetorical gambit, with little appreciation of the underlying principles. The paper elaborates on an important distinction between evidential and prudential varieties of burdens of proof, which is cashed out in terms of Bayesian probabilities and error management theory. Finally, we explore the relationship between burden of proof and several (alleged) informal logical fallacies. This allows us to get a firmer grip on the concept and its applications in different domains, and also to clear up some confusions with regard to when exactly some fallacies (ad hominem, ad ignorantiam, and petitio principii) may or may not occur.     

How School can Teach Civic Engagement Besides Civic Education: The Role of Democratic School Climate

Civic engagement, defined as involvement in community life, is influenced by reciprocal relationships between individuals and contexts and is a key factor that contributes to positive youth development. The present study evaluates a theoretical model linking perceived democratic school climate with adolescent civic engagement (operationalized as civic responsibility and intentions for future participation), taking into account the mediating role of civic discussions and perceived fairness at school. Participants were 403 adolescents (47.9 % male) ranging in age from 11 to 15 years old (mean age = 13.6). Path analysis results partially validated the proposed theoretical model. Higher levels of democratic school climate were associated with higher levels of adolescent civic responsibility; the association was fully mediated by civic discussions and perceived fairness at school. Adolescents’ civic responsibility, then, was positively associated with a stronger intention to participate in the civic domain in the future.     

Filtering visual onsets via habituation: A context-specific long-term memory of irrelevant stimuli

The fact that we are often immediately attracted by sudden visual onsets provides a clear advantage for our survival. However, how can we resist from being continuously distracted by irrelevant repetitive onsets? Since the seminal work of Sokolov (1963), habituation of the orienting of attention has long been proposed to be a possible filtering mechanism. Here, in two experiments, we provide novel evidence showing that (a) habituation of capture of focused visual attention relies on a stored representation of the distractor onsets in relation to their context, and (b) that once formed such representation endures unchanged for weeks without any further exposure to the distractors. In agreement with the proposal of Wagner (1979) concerning the associative nature of habituation, the results of Experiment 1 suggest that habituation of attentional capture is context specific. Furthermore, the results of Experiment 2 show that to filter visual distractors our cognitive system uses long-lasting memories of the irrelevant information. Although distractor filtering can be implemented via top-down inhibitory control, neural and cognitive mechanisms underlying habituation provide a straightforward explanation for the reduced distraction obtained with training, thus working like an automatic filter that prevents irrelevant recurring stimuli from gaining access to higher stages of analysis.     

Are the effects of attention on speed judgments genuinely perceptual?

A number of studies in recent years have suggested that exogenous and endogenous attention might enhance the perceived magnitude of various perceptual attributes, such as contrast and motion speed. Those studies have generally used comparative judgments as a measure to assess the point of subjective equality; however, similarity judgments have been proposed as possibly less prone to decision biases (Schneider & Komlos, 2008). In three experiments, using a similarity judgment task, we did not find any evidence of motion speed enhancement by exogenous attention. We suggest that the effect revealed by comparative judgments arises at the decisional, rather than the perceptual, stage.