The Timing Effects of Accent Production in Periodic Finger-Tapping Sequences

When subjects are required to produce short sequences of equally paced finger taps and to accentuate one of the taps, the interval preceding the forceful tap is shortened and the one that immediately follows the accent is lengthened. Assuming that the tapping movements are triggered by an internal clock, one explanation attributes the rnistiming of the taps to central factors: The momentary rate of the clock is accelerated or decelerated as a function of motor preparation to, respectively, increase or decrease the movement force. This hypothesis predicts that the interresponse intervals measured between either tap movement onsets or movement terminations (taps) will show the same timing pattern. A second explanation for the observed interval effects is that the tapping movements are triggered by a regular internal clock but the timing of the successive taps is altered because the forceful movement is completed in less time than the other tap movements are. This "peripheral" hypothesis predicts regular timing of movement onsets but distorted timing of movement terminations. In the present study, the trajectories of the movements performed by subjects were recorded and the interresponse intervals were measured at the beginning and the end of the tapping movements. The results of Experiment 1 showed that neither model can fully explain the interval effects: The fast forceful movements were initiated with an additional delay that took into account the small execution time of these movements. Experiment 2 reproduced this finding and showed that the timing of the onset and contact intervals did not evolve with the repetition of trial blocks. Therefore, the assumption of an internal clock that would trigger the successive movements must be rejected. The results are discussed in the framework of a modified two-stage model in which the internal clock, instead of triggering the tapping movements, provides target time points at which the movements have to produce their meaningful effects, that is, contacts with the response key. The timing distortions are likely to reflect both peripheral and central components.     

The development of the Telic Dominance Scale

The development of a 42-item measure of a number of personality features derived from the theory of psychological reversals is reported. These personality features are (a) the extent to which a person is serious-minded, (b) the extent to which a person plans ahead and organizes himself in the pursuit of goals, and (c) the extent to which a person seeks to avoid arousal. These features together are seen to constitute a personality trait which is described as telic dominance. Data concerning the test-retest reliability, criterion-related and construct validity of the Telic Dominance Scale are presented, together with the scale and scoring key.     

Intrinsic feedback, interpolation, and the closed-loop theory

The amount of experience of a target location, or its surrounding locations, was manipulated to test Adams' (1971) prediction that the perceptual trace (stored perception of the correct response) is based on repeated sensations of the correct response. Sixteen learning trials, each followed by knowledge of results, on a linear-positioning task were permitted for all subjects. Each learning trial required movement to an adjustable physical stop. In learning condition without target experience, movements never terminated in a zone within which the target was interpolated. Other groups experienced movements terminating at the target point. The strength of the perceptual trace was inferred from the ability to move to the target during 20 test trials with the stop removed and without knowledge of the results. Slow movements could be made to a novel location equally as well as to a repeatedly practiced location.     

Lateralized concomitants of human handedness

Literature was reviewed concerning lateral asymmetries of brain and behavior in normal and pathological populations of left-and right-handers. Cerebral asymmetries of structure and function are less pronounced in left-handers as a group than in right-handers as a group, and variability is greater in left-handers.     

A multi-systems theory of the structure and dynamics of motor functions

A theoretical analysis of the structure and dynamics of human motor functioning is presented from the perspective of a general theory of individuality. Within multifactor-systems theory, the structural units of the six systems of integrative personality (i.e., sensory, motor, cognitive, affect, style, and value) are hierarchical factor structures. Integrative functioning, both within and among systems, is described via the principles of general systems and information-processing theory. Our theoretical synthesis of the structure and dynamics of human motor functioning involves conceptualizing the hierarchy of motor factors as: (a) the basic dimensions of individual differences in the motor domain, (b) classes of decomposable motor programs that specify the spatio-temporal organization of behavior, and (c) decomposable classes of processing components entailed by motor programs. Some of the implications for understanding the role of affect in motor functioning and some research suggestions were presented.