Contextual interference in learning precision skills

This research studied the effect of different organisations of practice (blocked and random) on the learning of three different types of throwing. 35 male students practiced three precise throws for 3 wk. Initially the subjects were separated into two groups who trained under different conditions of practice (blocked and random). All subjects improved significantly from initial performance, with both blocked practice and random practice. At the end of acquisition no differences were found between the groups. No significant differences were found on retention tests carried out 48 hr., 4 wk., and 8 wk. after the training period.     

Effects of acute, repeated and chronic variable stress on in vivo tyrosine hydroxylase activity and on alpha(2)-adrenoceptor sensitivity in the rat brain

We assessed the effects of a single tail pinch and two chronic stress regimes, repeated and variable, on in vivo tyrosine hydroxylase activity and on alpha2-adrenoceptor sensitivity in two brain regions. After administering a 3,4-dihydroxyphenylalanine (DOPA) decarboxylase inhibitor, tyrosine hydroxylase activity, measured as the accumulation of DOPA, and noradrenaline (NA) content were determined by using high-performance liquid chromatography. A single tail pinch for 5 min induced an enhancement of DOPA content in hippocampus (28%) and hypothalamus (67%) which was still present 24 h later. This increase could account for the lack of changes in NA content in both regions after the application of this stressor. However, tyrosine hydroxylase activity was unmodified 24 h after exposure to both repeated (5 min of tail pinch, twice daily, for 14 days) and chronic variable stress (one of 5 different stressors, once daily, for 14 days) although there was an enhancement of NA levels in hippocampus (45 and 54%, respectively) and hypothalamus (24.5 and 36%, respectively). The sensitivity of the alpha2-adrenoceptors which regulate [3H]-NA release in hippocampal and hypothalamic synaptosomes was not modified by the acute or chronic stress protocols assayed. The results show that both paradigms of chronic stress had similar effects on the noradrenergic indices evaluated.     

Alexithymia--state or trait?

Alexithymia refers to a specific disturbance in emotional processing that is manifested by difficulties in identifying and verbalizing feelings and a tendency to focus on and amplify the somatic sensations that accompany emotional arousal. Alexithymia is conceptualized both as an affect-deficit disorder and a continuous personality variable. The main purpose of the present study was to investigate the stability levels of alexithymia with regard to changes in emotional distress levels caused by university exams. We tested 20 university students at four different times, before and after the exams. Alexithymic features and self-reported emotional distress (trait anxiety and physical symptoms) were measured. Whereas emotional distress measures changed significantly during the diverse phases, the level of alexithymia remained unchanged. We therefore conclude that alexithymia represents a constant trait.     

Differential efficacy of a cognitive-behavioral intervention versus pharmacological treatment in the management of fibromyalgic syndrome

Given that studies about the differential efficacy of existing treatments in fibromyalgia syndrome are scarce, the aim of this study was to compare the differential efficacy of a cognitive-behavioral and a pharmacological therapy on fibromyalgia. Using a randomized controlled clinical trial, 28 fibromyalgic patients were assigned to one of following experimental conditions: (a) pharmacological treatment (i.e., cyclobenzaprine), (b) cognitive-behavioral intervention (i.e., stress inoculation training), (c) combined pharmacological and cognitive-behavioral treatment and (d) no treatment. The results show the superiority of cognitive-behavioral intervention to reduce the severity of fibromyalgia both at the end of the treatment and at follow-up. We conclude that cognitive-behavioral interventions must be considered a primary treatment of fibromyalgia syndrome.     

Germs and angels: the role of testimony in young children's ontology

In three experiments, children's reliance on other people's testimony as compared to their own, first-hand experience was assessed in the domain of ontology. Children ranging from 4 to 8 years were asked to judge whether five different types of entity exist: real entities (e.g. cats, trees) whose existence is evident to everyone; scientific entities (e.g. germs, oxygen) that are normally invisible but whose existence is generally presupposed in everyday discourse; endorsed beings (e.g. the Tooth Fairy, Santa Claus) whose existence is typically endorsed in discourse with young children; equivocal beings (e.g. monsters, witches) whose existence is not typically endorsed in discourse with young children; and impossible entities (e.g. flying pigs, barking cats) that nobody believes in. Children make a broad dichotomy between entities and beings that they claim to exist (real entities; scientific entities; and endorsed beings) and those whose existence they deny (equivocal beings and impossible entities). They also make a more fine-grained distinction among the invisible entities that they claim to exist. Thus, they assert the existence of scientific entities such as germs with more confidence than that of endorsed beings such as Santa Claus. The findings confirm that children's ontological claims extend beyond their first-hand encounters with instances of a given category. Children readily believe in entities that they cannot see for themselves but have been told about. Their confidence in the existence of those entities appears to vary with the pattern of testimony that they receive.     

Visual and tactile guidance of dexterous manipulation tasks: an fMRI study

Models of motor guidance that dynamically adjust to the availability and quality of sensory information are based on the observation that dexterous tasks are routinely performed using various combinations of visual and tactile inputs. However, a dynamic neural system that acquires and processes relevant visual and tactile information remains relatively uncharacterized in humans. In this study, whole-brain functional magnetic resonance images were acquired during a dexterous manipulation task, compression of the end caps of a slender spring prone to buckling, to investigate the neural systems associated with motor guidance under four visual and tactile guidance conditions: (1) eyes closed (no visual input), smooth end caps, (2) eyes dosed, rough end caps, (3) eyes open and watching hand, smooth end caps, and (4) eyes open and watching hand, rough end caps. Performance of the dexterous task remained constant in all conditions. Variations in the two levels of visual input resulted in modulation of activity in the middle and inferior occipital gyrii and inferior parietal lobule, and variation in the two levels of tactile input during the task resulted in modulation of activity in the precentral (primary motor) gyrus. Although significantly active in all conditions, cingulate gyrus, medial frontal gyrus, postcentral gyrus, and cerebellum activities were not modulated by levels of either visual or somatosensory input, and no interaction effects were observed. Together, these data indicate that a fine-tuned motor task guided by varying visual and tactile information engages a distributed and integrated neural complex consisting of control and executive functions and regions that process dynamic sensory information related to guidance functions.     

Visual behavior and perception of trajectories of moving objects with visual occlusion

Experienced athletes in sports with moving objects have shown greater skill when using visual information to anticipate the direction of a moving object than nonexperienced athletes of those sports. Studies have shown that expert athletes are more effective than novices in occlusion situations in the first stages of the sports sequence. In this study, 12 athletes with different competitive experience in sports with moving objects viewed a sequence of tennis ball launches with and without visual occlusion, launched by a ball-shooting machine toward different areas with respect to the participant's position. The relation among visual behavior, occlusion time, and the precision of the task is reviewed. The spot where the balls bounced was analysed by a digital camera and visual behavior by an Eye Tracking System. Analysis showed that the nonexperienced athletes made significantly more errors and were more variable in visual occlusion conditions. Participants had a stable visual search strategy.     

Associative and causal reasoning accounts of causal induction: Symmetries and asymmetries in predictive and diagnostic inferences

Associative and causal reasoning accounts are probably the two most influential types of accounts of causal reasoning processes. Only causal reasoning accounts predict certain asymmetries between predictive (i.e., reasoning from causes to effects) and diagnostic (i.e., reasoning from effects to causes) inferences regarding cue-interaction phenomena (e.g., the overshadowing effect). In the experiments reported here, we attempted to delimit the conditions under which these asymmetries occur. The results show that unless participants perceived the relevance of causal information to solving the task, predictive and diagnostic inferences were symmetrical. Specifically, Experiments 1A and 1B showed that implicitly stressing the relevance of causal information by having participants review the instructions favored the presence of asymmetries between predictive and diagnostic situations. In addition, Experiment 2 showed that explicitly stressing the relevance of causal information by stating the importance of the causal role of events after the instructions were given also favored the asymmetry.     

"Economic man" in cross-cultural perspective: behavioral experiments in 15 small-scale societies

Researchers from across the social sciences have found consistent deviations from the predictions of the canonical model of self-interest in hundreds of experiments from around the world. This research, however, cannot determine whether the uniformity results from universal patterns of human behavior or from the limited cultural variation available among the university students used in virtually all prior experimental work. To address this, we undertook a cross-cultural study of behavior in ultimatum, public goods, and dictator games in a range of small-scale societies exhibiting a wide variety of economic and cultural conditions. We found, first, that the canonical model - based on self-interest - fails in all of the societies studied. Second, our data reveal substantially more behavioral variability across social groups than has been found in previous research. Third, group-level differences in economic organization and the structure of social interactions explain a substantial portion of the behavioral variation across societies: the higher the degree of market integration and the higher the payoffs to cooperation in everyday life, the greater the level of prosociality expressed in experimental games. Fourth, the available individual-level economic and demographic variables do not consistently explain game behavior, either within or across groups. Fifth, in many cases experimental play appears to reflect the common interactional patterns of everyday life.