Evidence for processing stages in skill acquisition: a dual-task study

We investigated the changes of resource demand during the acquisition of a sensorimotor skill, namely the tracking of a visual target under reversed visual feedback. This acquisition task was performed alone or concurrently with one of four manual reaction-time tasks as loading tasks, designed to tap different computational resources. As expected, we found tracking performance to deteriorate upon vision reversal and then to gradually improve with practice. We further found that acquisition task and loading task interfered little before vision reversal but substantially afterwards. Most importantly, we observed a different time-course of interference for each of our four loading tasks. The particular pattern led us to conclude that resources related to spatial attention and sensory transformations are in highest demand early during skill acquisition and those pertinent to movement preparation somewhat later. Our findings thus provide experimental support for the theory that motor learning progresses in stages characterized by different resource requirements.     

Early modulation of visual perception by emotional arousal: Evidence from steady-state visual evoked brain potentials

Allocation of processing resources to emotional picture stimuli was examined using steady-state visual evoked brain potentials (ssVEPs). Participants viewed a set of 60 colored affective pictures from the International Affective Picture System, presented in a flickering mode at 10 Hz in order to elicit ssVEPs. Phase and amplitude of the 10-Hz ssVEP were examined for six picture categories: threat and mutilation (unpleasant), families and erotica (pleasant), and household objects and persons (neutral). Self-reported affective arousal and hedonic valence of the picture stimuli were assessed by means of subjective ratings. Viewing affectively arousing (unpleasant and pleasant) pictures was associated with enhanced ssVEP amplitude at parieto-occipital recording sites, as compared with neutral stimuli. Phase information suggested increased coactivation of right occipitotemporal and frontotemporal sources during processing of affectively arousing stimuli. These findings are consistent with reentrant modulation of early visual processing by distributed networks including subcortical and neocortical structures according to a stimulus's motivational relevance.     

A comparison of the contrast effects in sound localization in the horizontal and vertical planes

The effect of a background sound on the auditory localization of a single sound source was examined. Nine loudspeakers were arranged crosswise in the horizontal and the median vertical plane. They ranged from -20 degrees to +20 degrees, with the center loudspeaker at 0 degree azimuth and elevation. Using vertical and horizontal centimeter scales, listeners verbally estimated the position of a 500-ms broadband noise stimulus being presented at the same time as a 2 s background sound, emitted by one of the four outer loudspeakers. When the background sound consisted of continuous broadband noise, listeners consistently shifted the apparent target positions away from the background sound locations. This auditory contrast effect, which is consistent with earlier findings, equally occurred in both planes. But when the background sound was changed to a pulse train of noise bursts, the contrast effect decreased in the horizontal plane and increased in the vertical plane. This discrepancy might be due to general differences in the processing of interaural and spectral localization information.     

Context-gated knowledge partitioning in categorization

According to the knowledge partitioning framework, people sometimes master complex tasks by creating multiple independent parcels of partial knowledge. Research has shown that knowledge parcels may contain mutually contradictory information, and that each parcel may be used without regard to knowledge that is demonstrably present in other parcels. This article reports 4 experiments that investigated knowledge partitioning in categorization. When component boundaries of a complex categorization were identified by a context cue, a significant proportion of participants learned partial and independent categorization strategies that were chosen on the basis of context. For those participants, a strategy used in one context was unaffected by knowledge demonstrably present in other contexts, suggesting that knowledge partitioning in categorization can be complete.     

Subgrouping in obesity based on Rorschach personality characteristics

Conceptual (a priori) subgroups in obesity based on personality findings from the Rorschach Comprehensive System were suggested for 100 obese patients. The subgroups were further compared in terms of general anamnestic and behavioral data. The largest subgroup was Rorschach characterized by difficulties with emotions and a tendency towards depression. Demographic and behavioral data for this subgroup revealed intermediate or higher education, regular meals, eating disorders like binge eating, periodic variations in eating during the year and experiencing body size as having a psychological meaning. The other subgroup was characterized by coping liabilities and was further associated with a lower socio-economic level and irregular or chaotic meal patterns. For the group with emotional difficulties, the results suggest a more complex psychological pattern, where eating and emotions could be closely related. The group with coping liabilities could have difficulties other than emotional ones concerning food and eating, such as finding a structure for eating and making changes in lifestyle and habits.     

Stability of inter-joint coordination during circle drawing: effects of shoulder-joint articular properties

The present study addressed the effect of articular conformity of the shoulder joint on the stability of inter-joint coordination during circular drawing movements. Twelve right-handed participants performed clockwise and counter-clockwise circular drawing movements at nine locations in the mid-sagittal plane. The task was paced acoustically at 1.0, 1.5 and 2.0 Hz and performed without visual control. Displacements of seven infrared light emitting diodes that were fixated at relevant joints were sampled at 100 Hz by means of a 3D-motion tracking system (Optotrak 3020). From these data, shoulder, elbow and wrist angular excursions were derived as well as the continuous relative phase of the proximal and distal joint pairs of the arm. The results confirmed earlier observations that the shoulder and elbow are more strongly coupled than the elbow and wrist in sagittal-plane movements. However, a typical characteristic of the architecture of the shoulder joint, that is, its built-in mechanical "joint play", was shown to induce a position-dependent variation in inter-joint coordination stability. We conclude that besides polyarticular-muscle induced synergies and inertial coupling, articular conformity of the shoulder joint constitutes an additional determinant of inter-joint coordination stability that, to date, has been neglected.     

Effect of anosmia on reproduction in male and female wolves (Canis lupus)

Anosmia was produced in two female and three male wolves by transection of the olfactory peduncle and was confirmed by their inability to detect meat, urine, feces, anal-gland secretions, and fish emulsion. All operated animals continued to investigate the environment with their noses, to interact normally with other pack members, and to feed at levels which maintained presurgical body weights. No effect was found on reproductive physiology (females: estradiol or progesterone concentrations, ovulation, pregnancy or parturition; males: testosterone, testicular recrudescence or sperm numbers, motility or maturation). One anosmic female became dominant and although she urine-marked with a flexed leg, the rate was lower than typical for dominant females and perhaps contributed to her failure to pair-bond with the dominant male. One anosmic male raised-leg-urinated while competing for pack dominance and when kenneled away from other males. Precopulatory, copulatory, and maternal behavior were observed for one anosmic female and appeared normal. However, neither male that was sexually naive before surgery showed interest in proestrous or estrous females. The possibility that secondary degeneration of brain regions mediating sexual behavior was responsible for the failure of these males to respond was not supported. Not only was the lack of male sexual response the only serious deficit following transection, but the male which was sexually experienced prior to surgery did copulate successfully during his second postoperative breeding season despite continued anosmia. Chemosensory priming from female urine during the protracted proestrous phase, as well as urinary and vaginal odors during estrus, appear to be critical for induction of full sexual potency in sexually naive males. The importance of urine and vaginal secretions in the sexual response of experienced males is uncertain.     

Protection Motivation Theory: Prediction of Intentions to Engage in Anti-Nuclear War Behaviors1

The present study examined potential mediators of intentions to engage in behaviors related to the prevention of nuclear war. Protection motivation theory (Rogers, 1975, 1983) suggested that perceived severity of the consequences of nuclear war, perceived likelihood of occurrence of nuclear war, perceived efficacy of responses designed to prevent nuclear war, and perceived capability of engaging in those responses would combine additively and interactively to predict behavioral intentions. The theory further suggested that the effects of a fear-arousing communication on behavioral intentions would be mediated indirectly by changes in the predictor variables. Thus, a second purpose of the study was to evaluate the effects of the program “The Day After”, which dramatically depicted a nuclear holocaust, on viewers' affect (fear-arousal) and cognitions. Surprisingly, the program had no effects on viewers that we could document. We were, however, able to predict behavioral intentions, for both viewers and nonviewers (n= 282), from subjects' affect and cognitions, providing support for protection motivation theory in a new domain.     

Self-, ingroup, and outgroup achievement attributions of German and Turkish pupils

The present study investigated intergroup bias in achievement attributions in a sample of 62 German and 55 Turkish pupils (aged 15 years) in the Federal Republic of Germany. The design was 2 x 2 x 2 x 3 (Ethnic Group x Outgroup Prejudice x Outcome x Stimulus) with repeated measures on the last two factors. Subjects attributed examination performance to ability, effort, luck, and task difficulty. Intergroup bias was limited to German pupils, who attributed failure of an ingroup member or self more to bad luck than they did that of an outgroup member. Turkish pupils acted more in terms of self than ingroup, attributing the success of another Turkish child more to good luck than they did that of self or an outgroup member. They also failed to distinguish clearly between success and failure in their task attributions. Results are discussed in terms of the inventive nature of explanations for ability-linked performance and the motivational consequences of causal attributions.