Stabilization and destabilization of perception--action patterns influence the self-organized recruitment of degrees of freedom

The recruitment of an additional biomechanical degree of freedom in a unimanual rhythmic task was explored. Subjects were asked to synchronize adduction or abduction of their right index finger with a metronome, the frequency of which was increased systematically. In addition, haptic contact on or off the metronome beat was provided. Results showed that the pattern exhibiting the highest intrinsic stability recruited the vertical plane more than did the less stable one. Moreover, presence and location of haptic contact modulated coordination stability and therefore induced changes in the recruitment of the vertical plane. Thus, a trade-off was shown between coordination stability on the horizontal plane and recruitment of the vertical one. These findings suggest that recruitment of degrees of freedom is governed by general principles of coordination dynamics.     

Processing reduced word forms: the suffix restoration effect

Listeners cannot recognize highly reduced word forms in isolation, but they can do so when these forms are presented in context (Ernestus, Baayen, & Schreuder, 2002). This suggests that not all possible surface forms of words have equal status in the mental lexicon. The present study shows that the reduced forms are linked to the canonical representations in the mental lexicon, and that these latter representations induce reconstruction processes. Listeners restore suffixes that are partly or completely missing in reduced word forms. A series of phoneme-monitoring experiments reveals the nature of this restoration: the basis for suffix restoration is mainly phonological in nature, but orthography has an influence as well.     

Task-set reconfiguration with predictable and unpredictable task switches

Participants switched frequently between high/low and odd/even classification of a digit. The interval between a task cue and the next digit varied between blocks. In Experiment 1, the task switched predictably every two, four, or eight trials. In Experiment 2, switching predictably every four trials was compared with random switching. With predictable switching, the cost was limited to the first trial of a run. Random switching produced a more gradual approach to asymptotic performance. After one performance, control processes attenuate the resulting change in task-set bias if a further switch is likely, but this strategic modulation is soon overwhelmed by task-set priming through further performances. Preparation reduced switch costs but not interference from the irrelevant attribute: Control of interference appears to be reactive, not proactive. Switch costs did not increase with run length, suggesting that retrieval of the task set last associated with the stimulus did not contribute to switch costs.     

On discontinuities in motor learning: a longitudinal study of complex skill acquisition on a ski-simulator

The qualitative behavioral reorganizations that occurred during the acquisition of a complex motor skill were examined. Five novice participants practiced for 39 sessions of ten 1-min trials on a modified version of the ski-simulator. Analyses focused on the motion of the apparatus platform, modeled as a self-sustained oscillator. At the beginning of the experiment, all participants adopted a behavior that could be modeled with a highly nonlinear stiffness function and a Rayleigh damping function. The behavior in the final part of the experiment was captured by a qualitatively different model, with a linear stiffness function and a van der Pol damping behavior. The transition from the initial to the final model was gradual and was marked in most cases by an abrupt increase of oscillation frequency. During the transition stage, the 2 damping behaviors seemed alternately exploited within each trial. The results are discussed in the framework of the dynamical systems approach to motor coordination and learning, considering motor skill acquisition as a phase transition.     

Demographic characteristics,social competence,and behavior problems in children with gender identity disorder: a cross-national,cross-clinic comparative analysis

This study examined demographic characteristics, social competence, and behavior problems in clinic-referred children with gender identity problems in Toronto, Canada (N = 358), and Utrecht, The Netherlands (N = 130). The Toronto sample was, on average, about a year younger than the Utrecht sample at referral, had a higher percentage of boys, had a higher mean IQ, and was less likely to be living with both parents. On the Child Behavior Checklist (CBCL), both groups showed, on average, clinical range scores in both social competence and behavior problems. A CBCL-derived measure of poor peer relations showed that boys in both clinics had worse ratings than did the girls. A multiple regression analysis showed that poor peer relations were the strongest predictor of behavior problems in both samples. This study—the first cross-national, cross-clinic comparative analysis of children with gender identity disorder—found far more similarities than differences in both social competence and behavior problems. The most salient demographic difference was age at referral. Cross-national differences in factors that might influence referral patterns are discussed.     

Modulation of tremor amplitude during deep brain stimulation at different frequencies

Rest tremor was quantified in the index finger tip of 16 patients with Parkinson's disease (PD) receiving deep brain stimulation (DBS) of the ventro-intermediate nucleus (Vim) of the thalamus, the subthalamic nucleus (STN), or the internal part of the globus pallidus (GPi) while being off L-dopa for 12h. Clinically, without DBS, tremor amplitude varied from absent to high. Tremor was recorded continuously for about 5 min under three conditions of DBS repeated twice, namely, effective frequency (E), ineffective frequency (I), and no DBS (O). No changes in tremor were observed across conditions in subjects with little or no tremor. However, in subjects with moderate to large amplitude tremor, DBS decreased tremor amplitude to near normal values within a few seconds. Generally, transitions were progressive and occurred with a varying time delay. Occasionally, tremor escaped from control regardless of the stimulation condition considered. In some cases tremor amplitude in one condition appeared to depend on the preceding condition. Finally, the results were reproducible on two consecutive days. We conclude that tremor control with DBS follows specific dynamical rules, which must be compatible with the hypotheses proposed regarding the underlying mechanisms of DBS.     

A cross-modal interference effect in grasping objects

The aim of the present paper was to investigate how the kinematics of a hand reaching toward a visual target would be influenced by haptic and proprioceptive input from an unseen distractor actively grasped in the other, nonreaching hand. The main results were that the amplitude of maximum grip aperture was smaller and the time to maximum grip aperture was earlier when the distractor was smaller than the target. The interference effect from the distractor was similar for both hands as they reached. Furthermore, results from a vibrating-distractor condition for passive tactile input revealed that the interference effects were evident only when the distractor was actively grasped. We suggest that neural processing of proprioceptive and tactile information relevant to distractor size produced the observed interference effects. We also emphasize the importance of active manipulation of the distractor stimulus in eliciting such interference effects.     

Pavlov in Spain

Reflexology has been present throughout Spanish science since the last third of the nineteenth century and its importance can be seen in the works of authors such as Martín Salazar, Ramón y Cajal, Gómez Oca?a, Simarro and Turró. The most important research in Reflexology in Spain takes place a) at the Schools of Neurophysiology and Psychology in Barcelona and Madrid, b) with a group of authors specializing in pathological medicine and c) in the Military's Health Department, Pavlov's work was received in Spain with special interest. Fernández-Espa?a, who could be considered the "first Spanish Pavlovian," emphasized Pavlov's work in a series dedicated to the study of objective psychology which was published between 1914 and 1924. Planelles was the first investigator to develop a program in pavlovian experimentation, presenting his results in 1935. The Civil War (1936-1939) ended these and many other Spanish projects in psychology. After the war, interest in Reflexology and Pavlov's theories slowly rose again, first through psychosomatic medicine and then in the 60's because of the works of such authors as Monserrat-Esteve, Rof Carballo and Colodrón. The progressive inclusion of psychology in the Schools of Philosophy and Arts after 1968 marked the beginning of a new era.     

Stereotype development in Andalusian children

Social psychologists have shown a profound interest in intergroup relationships, but there are very few papers focusing on the developmental aspects that explain the psychological mechanisms involved in the construction of group and cultural identity. Our research aims to explore how the self-categorization of Andalusian children evolves. We tried to assess the degree to which they self-identify as Andalusian, Spanish, and European, and how this identification changes with age. We were also interested in the affective evaluation of different groups (French, Italian, English, German, Spanish, Catalonian, and Andalusian) made by Andalusian children. Furthermore, we analyzed the relationship between self-categorization and the evaluation of these groups. Results show that the development of national (autonomous community) identity in these children is influenced by their cognitive development, as well as by the relationships among the regional communities of Spain and the relationships between Spain and other countries. The peculiarity of Andalusians as a group is that they assume both identities: Spanish and Andalusian, from a very early age. In-group favoritism is an extended phenomenon at all ages, and Andalusian children have a negative stereotype of the other Spanish groups and other European communities.     

The use of prosodic cues in language discrimination tasks by rats

Recent research with cotton-top tamarin monkeys has revealed language discrimination abilities similar to those found in human infants, demonstrating that these perceptual abilities are not unique to humans but are also present in non-human primates. Specifically, tamarins could discriminate forward but not backward sentences of Dutch from Japanese, using both natural and synthesized utterances. The present study was designed as a conceptual replication of the work on tamarins. Results show that rats trained in a discrimination learning task readily discriminate forward, but not backward sentences of Dutch from Japanese; the results are particularly robust for synthetic utterances, a pattern that shows greater parallels with newborns than with tamarins. Our results extend the claims made in the research with tamarins that the capacity to discriminate languages from different rhythmic classes depends on general perceptual abilities that evolved at least as far back as the rodents. Electronic Publication