Phases in Movement After-Effects and their relationship to the kinetic figural effect

Summary A Movement After-Effect (MAE) observed on a structured test figure contains generally two successive phases. The initial one is non-contingent upon the test figure and is assumed to result from an adaptation process. The second phase is shown to be contingent upon the features of the test figure and their similarity with those of the generating figure. A conditioning process is assumed to share in its appearance. In Experiment I, it is shown that the areal spread of MAE which may appear in the contingent phase is likely to result from a generalization process in which part of the test figure corresponding to an unstimulated area becomes transiently effective in generating a MAE. In Experiment II distributed practice of the MAE is shown to lead to an increase in the duration of the effect when the generating and test figures are similar. This last result suggests that the true conditioning stimulus is the generating figure as such.     

A measurement technique for stability as applied in rifle shooting

A technique is described for the measurement, in the field, of stability and steadiness. Apparatus and method are provided along with suggested scoring procedures.     

Should Common Optimal Movement Patterns Be Identified as the Criterion to Be Achieved?

Recently, a new paradigm has been proposed for the study of knowledge of performance (Schmidt & Young, 1991). In this paradigm, the experimenters identified an optimal kinematic movement pattern, based on the performance of a best subject, which was imposed on all subjects as the criterion to achieve. This approach, which assumes that this pattern is the best way for all subjects to do the task, was tested in the present experiment. In Experiment 1, a common optimal movement pattern could not be identified by an analysis of scatterplot graphs of the scores plotted as a function of various kinematic vanables or by correlating (within and across subjects [N = 14]) each kinematic variable with the score. In Experiment 2, subjects (N = 12) were retrained in 2 separate sessions, during which they tried to reproduce either a personal best or the best subject's template. Results indicated that scores were similar regardless of the template pattern being used. During training, however, subjects who used their personal template had a lower incidence of zero scores and were more consistent than those who used the template of the best subject. This provided a second line of evidence against the assumption that a common optimal movement pattern exists for this type of task.     

Signal clustering modulates auditory cortical activity in humans

Auditory streaming and its relevance to attentional processing was examined using event-related brain potentials (ERPs) in situations facilitating perception of one or two streams of sounds. Subjects listened to sequences of brief tones of three different frequencies presented in random order. In evenly spaced (ES) conditions, the three frequencies were equidistant on the musical scale. In clustered, easy (CE) conditions, the attended frequency was distinct, while the middle and extreme distractor tones were clustered together. In clustered, hard (CH) conditions, the attended frequency was clustered with one of the distractors. The subjects pressed a button in response to occasional target tones of longer duration at a prespecified frequency. The subjects were faster and more accurate in CE conditions than they were in ES conditions, and ERP attention effects were enhanced in amplitude in CE conditions. Conversely, the subjects were slower and less accurate in CH conditions and ERP attention effects were delayed in latency and decreased in amplitude. Clustering effects suggest that the processing of stimuli belonging to the attended stream was promoted and the processing of those falling outside the stream was inhibited. The timing and scalp distribution of clustering-related changes in ERPs suggest that clustering modulates early sensory processing in auditory cortex.     

La représentation sociale des droits de l'homme: Une recherche internationale sur l'étendue et les limites de l'universalité

La perception des violations des droits de l'homme par de jeunes individus insérés dans des contextes nationaux différents est-elle organisée selon des principes comparables à ceux d'experts ou d'institutions internationales? La présente étude contribue à élucider cette question en la situant dans le champ de la psychologie sociale. La représentation sociale des droits humains a été analysée par le biais d'un questionnaire standardisé soumis à des sujets de quatre pays (Costa Rica, France, Italie et Suisse) âgés de 13 à 20 ans. Les résultats montrent que les individus partagent dans une large mesure une conception institutionnelle des droits humains. De fortes variations à l'intérieur et entre les contextes nationaux apparaissent néanmoins, en particulier dans la délimitation des libertés individuelles et du contrôle étatique.     

Immunocytochemical Mapping of an RDL-Like GABA Receptor Subunit and of GABA in Brain Structures Related to Learning and Memory in the Cricket Acheta domesticus

The distribution of putative RDL-like GABA receptors and of γ-aminobutyric acid (GABA) in the brain of the adult house cricket Acheta domesticus was studied using specific antisera. Special attention was given to brain structures known to be related to learning and memory. The main immunostaining for the RDL-like GABA receptor was observed in mushroom bodies, in particular the upper part of mushroom body peduncle and the two arms of the posterior calyx. Weaker immunostaining was detected in the distal part of the peduncle and in the α and β lobes. The dorso- and ventrolateral protocerebrum neuropils appeared rich in RDL-like GABA receptors. Staining was also detected in the glomeruli of the antennal lobe, as well as in the ellipsoid body of the central complex. Many neurons clustered in groups exhibit GABA-like immunoreactivity. Tracts that were strongly immunostained innervated both the calyces and the lobes of mushroom bodies. The glomeruli of the antennal lobe, the ellipsoid body, as well as neuropils of the dorso- and ventrolateral protocerebrum were also rich in GABA-like immuno- reactivity. The data demonstrated a good correlation between the distribution of the GABA-like and of the RDL-like GABA receptor immunoreactivity. The prominent distribution of RDL-like GABA receptor subunits, in particular areas of mushroom bodies and antennal lobes, underlines the importance of inhibitory signals in information processing in these major integrative centers of the insect brain.     

Information Exchange in Context: Effects of Gender Composition of Group,Accountability, and Intergroup Perception on Group Decision Making1

In the present study, the dissemination of shared and unshared information (cf. Stasser & Titus, 1985) in unstructured group discussion is analyzed. In previous experiments, several manipulations of the task itself were introduced, in search of conditions that could facilitate the exchange of unshared information. As such, these studies neglected the potential impact of context variables on group performance. In the present study, the effects of accountability, intergroup perception, and gender composition of group on information exchange are investigated. The results indicate that heterogeneous groups exchanged more information when a second group was present. Information exchange was not promoted by the presence of an outgroup for homogeneous groups. Groups in the accountability condition displayed more difficulties to reach agreement, but this did not lead to the mentioning of more information.     

Feature processing during high-rate auditory selective attention

Auditory event-related brain potentials (ERPs) and reaction times were, analyzed in a selective attention task in which subjects attended to tone pips presented at high rates-Xinterstimulua intervals [ISIs] of 40-200 msec). Subjects responded to infrequent target tones of a specified frequency (250 or 4000 Hz) and location (left or right ear) that were louder than otherwise identical tones presented randomly to the left and right ears. Negative difference (Nd) waves were isolated by subtracting ERPs to tones with no target features from ERPs to the same tones when they shared target location, frequency, or both frequency and location cues. Nd waves began 60-70 msec after tone onset and lasted until 252–350 msec after tone onset, even for tones with single attended cues. The duration of Nd waves exceeded the ISIs between successive tones, implying that several stimuli underwent concurrent analysis. Nd waves associated with frequency processing had scalp distributions different from those associated with location processing, implying that the features were analyzed in distinct cortical areas. Nd waves specific to auditory feature conjunction were isolated. These began at latencies of 110–120 msec, some 30-40 msec after the Nds to single features. The relative timing of the different Nd waves suggests that auditory feaure conjunction begins after a brief parallel analysis of individual features but before feature analysis is complete.