Sensorimotor synchronization: Motor responses to pseudoregular auditory patterns

Musically trained and untrained subjects (N=30) were asked to synchronize their finger tapping with stimuli in auditory patterns. Each pattern comprised six successive tonal stimuli of the same duration, the first of which was accented by a different frequency. The duration of interstimulus onset intervals (ISIs) gradually increased or decreased in constant steps toward the end of the patterns. Four values of such steps were used in different trials: 20, 30, 45, and 60 msec. Various time-control mechanisms are hypothesized as being simultaneously responsible for subjects’ incorrect reproduction of the internal temporal ratios of the stimulus patterns. The mechanism of assimilation (of a central tendency) led subjects to enforce a regular (isochronous) structure on the patterns. The influence of other time-control mechanisms (distinction, subjective expression of an accent, sequential transfer) was expressed mainly in differences between intertap onset intervals (ITIs) and the corresponding ISIs at the beginning of the patterns. The duration of the first two ITIs was in the majority of the trials in an inverse ratio to the ratio of the respective ISIs. The distortions resulting from the timing mechanisms concerned were more pronounced in the performance of nonmusicians than in that of musicians.     

Human sensitivity to temporal proximity: The role of spatial and temporal speed gradients

Estimates of temporal proximity (sometimes called time-to-collision) from random-dot flow patterns are shown to be based upon retinal speed, rather than upon changes in dot density. Neither the spatial nor the temporal gradient of motion is essential to the task, but estimates can be made from either alone. Performance is unaffected by the addition of rotational motion, suggesting that observers axe capable of extracting the radial component of motion, which contains all the relevant information, from complex stimuli.     

Reaction-anticipation transitions in human perception-action patterns

We investigated the hypothesis that reaction and anticipation in human perceptual-motor performance are two coordinative modes of a single pattern-forming dynamical system, rather than separate behaviors. Subjects coordinated the onset of finger flexions with visual metronome flashes in each of three patterns: reactive, synchronized, or syncopated. The stimulus frequency was progressively increased (0.125–1.375 Hz) or decreased (1.375-0.125 Hz) in small steps (0.125 Hz) every 10 cycles. We observed qualitative transitions in both the time interval between stimulus and corresponding action (Δt) and their relative phase (ø) at critical values of the stimulus frequency, corresponding to changes from ‘reactive-to-anticipatory’ and ‘anticipatory-to-reactive’ performance. Such transitions provide evidence of a single, multifunctional system, which can be adequately described by the dynamics of collective variables characterizing the respective perception-action patterns.     

Validation of a full body 3-D dynamic linked segment model

In studies related to human movement, linked segment models (LSM's) are often used to quantify forces and torques, generated in body joints. Some LSM's represent only a few body segments. Others, for instance used in studies on the control of whole body movements, include all body segments. As a consequence of the complexity of 3-dimensional (3-D) analyses, most LSM's are restricted to one plane of motion. However, in asymmetric movements this may result in a loss of relevant information. The aim of the current study was to develop and validate a 3-D LSM including all body segments. Braces with markers, attached to all body segments, were used to record the body movements. The validation of the model was accomplished by comparing the measured with the estimated ground reaction force and by comparing the torques at the lumbo-sacral joint that resulted from a bottom-up and a top-down mechanical analysis. For both comparisons, reasonable to good agreement was found. Sources of error that could not be analysed this way, were subjected to an additional sensitivity analysis. It was concluded that the internal validity of the current model is quite satisfactory.     

Merleau-Ponty,Marx, and Marxism: The problem of history

At the present time, Europe, particularly eastern Europe, is still immersed in a major political transformation, the most significant such change since the Second World War, arising out of the rejection of official Marxism. This unforeseen rejection requires meditation by all those concerned with the relation of philosophy to the historical context. Marxism, that follows Marx’s insistence on the link between a theory and the context in which it arises, cannot be indifferent to the rejection of Marxist theory in practice. In respect to the usual tendency to pass rapidly over practice for a theoretical analysis of social theory, Merleau-Ponty stands out for his concern to evaluate the theoretical claims of Marx and Marxism against practice.     

Types produce types—Especially fathers

Employing a larger sample and a more stringent statistical criterion, this study replicated an attempt by T. G. Grandy and R. F. Stahmann (Journal of Vocational Behavior, 1974, 5, 231–239.) to test Holland's hypothesis that parents' personality types foster similar offspring personality development. The relationships between paternal and offspring personality types were consonant with the findings of Grandy and Stahmann but the role of maternal personalities remained unclear. An explanation was offered that fathers' personality types carry more weight in the development of offspring types.     

A repertory grid study of therapist/couple interaction

A case of marital therapy is described in which the presenting problem, one of non-consummation, is treated by the standard Masters and Johnson's technique. Using repertory grids at the start and finish of treatment the changing perceptions of both partners and the therapist were determined. In spite of an ostensibly behavioural treatment, substantial changes occurred in the couple's understanding of the nature of their problem. The changes undergone in the couple's perceptions, and their differences from the therapist's assessments of change give rise to speculations about the nature of the therapeutic interaction and suggest further lines of exploration.     

Sleep,activity, temperature,and performance: Techniques for long-term monitoring in the mouse

This paper describes a test chamber, a food acquisition task, and a training procedure for the long-term testing of an implanted mouse in a circadian rhythm experiment. For the training phase, a special-purpose controller is provided to a single cage. For the experimental phase, behavioral, electrophysiological, and environmental measures are collected by means of a mini-computer.