Kinematics properties of rapid aimed hand movements

Generalized motor program theory and the models of Schmidt, Zelaznik, and Frank (1978), and Meyer, Smith, and Wright (1982) of speed-accuracy relationships in aimed hand movements require that the underlying acceleration-time patterns exhibit time rescalability, in which all acceleration-time functions in an aimed hand movement are generated from one rescalable pattern. We examined this property as a function of movement time in Experiment 1, and as a function of movement time and movement distance in Experiment 2. Both experiments failed to demonstrate strict time rescalability in acceleration-time patterns, with the time to peak positive acceleration being invariant across movement time. This suggests that time rescalability is not a necessary condition for the linear relation between speed and spatial variability. A second major finding was that the variability in distance traveled at the end of positive acceleration was independent of movement time, contrary to the symmetric-impulse-variability model of Meyer et al. (1982). The findings of both experiments suggest that the processes involved in decelerating the limb play an important, but yet to be understood, role in determining the linear speed-accuracy trade-off. Finally, these results suggest that generalized motor programs are not based on simple, time-rescalable acceleration patterns.     

Application of the Theory of Planned Behavior to Adolescents’ Condom Use: A Panel Study1

The authors report a longitudinal study of factors determining use of condoms with new sexual partners in a representative sample of 650 German youth. Measures derived from the theory of planned behavior (Ajzen, 1985) were obtained in 2 waves separated by 1 year. Consistent with the theory, intentions to use condoms could be predicted from attitudes, subjective norms, and perceived behavioral control with respect to this behavior; and actual condom use was strongly related to intentions and perceptions of control assessed in Wave 2. Due to changes in beliefs and attitudes over time, only about 10% of the variance in reported condom use was accounted for by intentions and perceived control assessed 1 year earlier. Reported condom use was found to exert a direct effect on later intentions, unmediated by their hypothesized antecedents. Theoretical and practical implications of these findings are discussed.     

Category typicality effects in episodic memory: Testing models of distinctiveness

Middle Tennessee State University, Murfreesboro, Tennessee Category typicality effects were investigated within the context of three models of distinctiveness: a univariate model, a fixed-multifeature model, and a weighted-multifeature model. High-typical, medium-typical, and atypical targets were embedded in lists containing a background set of mediumto high-typicality items. Atypical items were more poorly recalled than were medium- and high-typical items independently of list structure. In recognition, subjects who studied high-typical items had difficulty discriminating between high-typical items that were and were not presented as part of the list. However, item typicality had little effect on the recognition performance of subjects who did not study high-typical items. These findings were consistent with the weighted-multifeature model of distinctiveness.     

Cognitive triad: Relationship to depressive symptoms,parents' cognitive triad,and perceived parental messages

Evaluating the relationship between children's depressogenic thinking, children's depressive symptoms, parents' depressogenic thinking, and perceived parental messages about the self, world, and future was the primary objective of this investigation. Children (n =133) from grades 4 to 7 completed measures of depression and anxiety, including a semistructured clinical interview, a measure of their cognitive triad, and a measure of perceived parental messages about the self, world, and future. Mothers (n =112) and fathers (n =95) completed a measure of their own cognitive triad. Results of a series of regression analyses revealed that (1) children's views of self, world, and future (cognitive triad) are related to severity of depression; (2) mothers' but not fathers' cognitive triads are related to their children's cognitive triads; (3) perceived parental messages to the children about the self, world, and future are predictive of the children's cognitive triads and ratings of depression; and (4) the relationship between perceived parental messages and depression is completely mediated by children's cognitive triads. Analyses of covariance indicated that the obtained mediational relationship between children's views of self, world, and future, perceived parental messages, and children's depressive symptoms was specific to depressive versus anxious symptomatology. Impfications for existing theory and research are discussed.     

Birth Control Versus AIDS Prevention: A Hierarchical Model of Condom Use Among Young People1

The authors report the results of a nationwide survey of young people in Germany which applied the theory of planned behavior (Ajzen, 1985, 1991) to condom use for purposes of birth control and with new sexual partners (to prevent AIDS). A hierarchical model, in which the 2 functions of condom use were treated as separate 2nd-order factors, was found to be superior to a single-factor model. The hierarchical model also provided evidence for the convergent and discriminant validities of indicators used to assess the constructs in the theory of planned behavior. Attitudes, subjective norms, and perceptions of behavioral control all made significant contributions to the predictions of intentions, accounting for 62.0% and 70.9% of the variance for birth control and AIDS prevention, respectively. Perceived behavioral control carried most of the weight in the former prediction, while attitudes carried most of the weight in the latter. Implications of these findings are discussed.     

Is hostility linked with affiliation among males and with achievement among females? A critique of Pollak and Gilligan

This investigation attempted to replicate and to clarify methodologically an investigation by Pollak and Gilligan (1982). Those investigators reported sex differences in violence imagery to Thematic Apperception Test (TAT) pictures depicting affiliation and achievement situations. Pollak and Gilligan concluded that men perceive danger in situations of affiliation whereas women perceive danger in situations of achievement. It was demonstrated in the present study that Pollak and Gilligan incorrectly classified TAT cards into motivational categories, which may have resulted in incorrect inferences. In addition, their findings could not be replicated when using four different systems for classifying TAT cards into motivational categories. Other potential sources of error in their research, including a restrictive scoring scheme for hostility, unusual instructions, and failure to control for sex role in the TAT pictures, did not influence the pattern of results.     

DO ELEPHANTS EVER FORGET?1

Three adult female elephants (Elephas maximus) were tested on a light-dark discrimination problem with an 8-yr intertrial interval. The first subject took only 6 min to reach criterion and made only two errors, suggesting remarkable retention. The other two subjects were found to have visual anomalies that would have gone undetected without this research.     

Studies on protein genetic factors in multiple sclerosis and psychoses]

In more than 200 cases of multiple sclerosis, psychosis and cyclothymia, the Hp types are studied with the help of polyacrylamide gel electrophoresis (Schreyer and Schaible, 1967) and the Gc types wtih agar gel electrophoresis (Schlesinger, Vogt and Prokop, 1963). All Hp and Gc types were found in these diseases, but there was no frequent occurence of any particular type in multiple acleroses of psychoses. According to our results, there is no interdependence between these diseases and the Hp and Gc types.