The influence of perceptual and motor factors on bimanual coordination in a polyrhythmic tapping task

Summary In this study the role of perceptual and motor factors on the motor organization (integrated versus parallel) adopted by musically skilled and unskilled subjects in a polyrhythmic tapping task was investigated. Subjects tapped a 3:2 polyrhythm to match the timing of two isochronous tone trains, one tone train for each hand. Perceptual factors were examined by the manipulation of the frequency difference between the tone trains to produce either an integrated or a streamed percept. Motor factors were examined by comparison of performance on two versions of the 3:2 polyrhythm. In one (simultaneous) version, each cycle of the polyrhythm began with a simultaneous left- and right-hand tap. In the other (shifted) version a 100-ms interval was introduced between the initial left and right taps in each cycle. Examination of the pattern of variances and covariances among intertap intervals suggested that most of the subjects in this study adopted an integrated motor organization that involved interleaving the timing of the two hands. Further analysis revealed that a serial chained model described the pattern of covariances best for the simultaneous pattern, whereas a hierarchical organization described the pattern of covariances for the shifted pattern best. The finding that performance was more accurate with integrated tones than with streamed tones provides some support for a perceptual-motor facilitation hypothesis.     

Marked sex differences on a fine motor skill task disappear when finger size is used as covariate

Purdue Pegboard performance of 16 male and 25 female right-handed college students were compared, and results were replicated with 25 male and 28 female subjects. In agreement with the literature, women performed significantly better than men. When measures of index finger and thumb thickness were used as covariate, all significant sex differences in performance disappeared. Negative correlations between performance and finger size were observed in both sexes. Sex differences in fine manual dexterity tasks may therefore be confounded by sex differences in finger size.     

Endogenous and symptomatic schizophrenia. Wherein lies the difference?

It is the opinion of the present writer that endogenous and symptomatic schizophrenia are two completely different matters. By classical symptomatology it is impossible to establish the distinction in every individual case. Nevertheless, in not one of the published cases known to us did Bonhoeffer err in his diagnosis of the one or the other. Evidently he made use of additional characteristica gathered in practice, about which he himself may not always have been quite clear.     

Stress,coping, and adjustment in mothers and young adolescents in single- and two-parent families

Compared stress, coping, and psychological adjustment in single (divorced or separated) and married mothers and their young adolescent children. Single mothers reported more daily hassles related to economic, family, and personal health problems, and more symptoms of depression, anxiety, and psychoticism. Single mothers also reported using more coping strategies related to accepting responsibility and positive reappraisal. After controlling for level of family income, differences in family hassles and coping strategies remained significant. The two groups did not differ on subtypes of symptoms after controlling for income, but single mothers still reported more total psychological symptoms. No differences were found between children in these two family constellations on maternal reports of emotional/behavioral problems or on children's self-reported emotional/behavioral problems, stressful events, or coping. Implications of these findings for adjustment to life in single-parent families are discussed.     

On the distinction between artifacts and information

Sperling, Landy, Dosher, and Perkins (1989) argued that all previous research on the kinetic depth effect has been contaminated by stimulus artifacts, and they developed a new task that they believe can successfully overcome this problem. The present discussion offers a counter-argument that artifacts are not as pervasive in previous research as Sperling et al. imply and that their proposed method is subject to precisely the same limitations as earlier studies. Also discussed are some general guidelines of experimental design in this type of research to minimize the possibility that subjects will adopt an inappropriate response strategy that does not truly reflect their visual perceptions of three-dimensional form.     

Visual perception of smoothly curved surfaces from double-projected contour patterns

This research was designed to examine how human observers are able to perceive the 3-dimensional structure of smoothly curved surfaces from projected patterns of surface contours. Displays were generated by using a method of double projection that made it possible to cover a surface with a wide range of contour patterns of varying geometric structure and to eliminate systematic variations of image shading. The compelling impression of 3-dimensional form from these patterns provides strong evidence that the ability of observers to perceptually interpret surface contours is considerably less restrictive than would be reasonable to expect on the basis of existing computational models. Results suggest that the perceptual analysis of surface contours is able to exploit statistical regularities of contour structure over appropriately large regions of visual space.     

Motivational Systems and Stress-Related Cardiovascular Reactivity

This study examined the relation of motivational systems to patterns of autonomic responses to stress. Specifically, we examined patterns of physiological response resulting from differential activation of motivational systems for behavioral approach and behavioral inhibition. We also examined the relation of these motivational systems to threat and challenge responses to potential stress. Self-report, cardiac measures (i.e., pre-injection period, or PEP, and heart rate, or HR), and blood pressure (i.e., systolic blood pressure, or SBP, and diastolic blood pressure, or DBP) measures reliably distinguished between an experimental condition facilitating behavioral approach and an experimental condition facilitating coactivation of behavioral approach and behavioral inhibition systems. Vascular (e.g., total peripheral resistance, or TPR) and electrodermal (e.g., electrodermal response, or EDR) measures, however, did not vary by condition. We discuss the results in relation to other research on motivational factors as they relate to stress and cardiovascular reactivity.     

Gender Differences in Intercepting A Moving Target by Using a Throw or Button Press

Humans are a throwing species just as much as a talking species (Calvin, 1982), but preadaptations for throwing remain largely unexplored. The ability of undergraduate students (N = 165) to intercept a stimulus with a thrown object was determined for 10 stimulus speeds, ranging from 2 to 5 m/s. The inclusion of a condition in which the moving stimulus was intercepted. via button press allowed the role of the perceptual aspect of velocity estimation to be evaluated separately from the act of throwing. Gender differences were observed in both the button and the throwing intercept tasks: The men had smaller timing errors and higher accuracy than the women. Contrary to expectations, the male and female patterns of intercept errors as a function of stimulus speed were more similar in the throwing task than in the button intercept task     

Understanding the Determinants of Consumer Composting Behavior1

This study compared 3 models of waste management behavior: (a) a theory of reasoned action model, (b) an environmental belief-behavior model, and (c) an integrated waste management model which is based on the theory of planned behavior. The three models were compared using data from a sample of over 1,400 individual respondents who each completed a survey and a 2-week diary of their consumer composting activities. Overall, the results suggest that while the environmental beliefs-behavior model and the integrated waste management models both fit the data well, the integrated waste management model provided better predictive power and offers significant insight into the factors that influence composting behavior.