Visual and Kinesthetic Components of Pursuit-Tracking Performance

Ss (N=75) were trained on a pursuit rotor for 10 trials with ambient illumination from a strobe light flashing at frequencies of either 2, 5, 10, 15, or 20/sec. A transfer trial followed, with a strobe flashing frequency of 10/sec for all Ss. Results supported hypotheses derived from Adams’ (1971) closed-loop theory of motor learning that (a) performance would improve during training as a function of amount of visual feedback available, and that (b) if after training visual feedback was reduced, performance would be maintained to the extent that reliance upon kinesthetic feedback had been learned as an alternate compensatory feedback loop.     

Dissociation of Bimanual Responses With the Simon Effect: On the Nonunitization of Bimanual Responses

The authors examined whether responses of the 2 hands were completely unitized when participants (N = 36) produced bimanual responses to lateralized targets in a Simon-type paradigm. Their primary aim was to investigate whether lateralized stimuli differentially influence the response dynamics of the 2 hands. Simon effects were obtained in reaction time and force; components of the bimanual response by the hand on the same side as the lateralized stimulus were more forceful than were those of the other hand. Also, Simon effects were larger when the lateralized target appeared alone than when it was accompanied by a distractor on the other side of the display. Finally, responses of the 2 hands were correlated most strongly when stimulus displays were symmetrical. The authors conclude that bimanual responses are strongly coupled, but not perfectly so.     

Relative Phase Alterations during Bimanual Skill Acquisition

The purposes of the research reported here were (a) to examine changes in relative phase during the acquisition of a new coordination pattern and (b) to determine the effect of learning this pattern on the ability to perform other coordination patterns. Ten subjects practiced an upper limb coordination task that required a 90° phase offset and different amplitudes for each arm. A gross approximation of the mean relative phase for the intended coordination pattern occurred quickly, but the attainment of stability occurred much more gradually. These results were accompanied by changes in pattern stability across practice and on various transfer tests. Learning of the new coordination pattern also affected the stability of the anti-phase mode, but this effect was only temporary.     

Sequential and Biomechanical Factors Constrain Timing and Motion in Tapping

The authors examined how timing accuracy in tapping sequences is influenced by sequential effects of preceding finger movements and biomechanical interdependencies among fingers. Skilled pianists tapped sequences at 3 rates; in each sequence, a finger whose motion was more or less independent of other fingers' motion was preceded by a finger to which it was more or less coupled. Less independent fingers and those preceded by a more coupled finger showed large timing errors and change in motion because of the preceding finger's motion. Motion change correlated with shorter intertap intervals and increased with rate. Thus, timing of sequence elements is not independent of the motion trajectories that individuals use to produce them. Neither motion nor its relation to timing is invariant across rates.     

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 mistiming 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 interre-sponse 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.     

Perception—Action Coupling during Bimanual Coordination: The Role of Visual Perception in the Coalition of Constraints That Govern Bimanual Action

Constraints pertaining to interlimb coordination have been studied extensively in the past decades. In this debate, F. Mechsner (2004) has taken a provocative position by putting primary emphasis on perceptual principles that mediate coordinative stability. Whereas the present authors agree that the role of perceptual principles is of critical importance during coordination, they take issue with Mechsner's extreme position and with the evidence forwarded to support a purely perceptual-cognitive approach to bimanual coordination. More specifically, the authors emphasize that current knowledge about brain function argues against a dualism between perception and action, criticize the presented evidence that posture manipulations during coordination provide decisive evidence against motoric and muscular constraints, and report on potential pitfalls associated with the use of visual transformation procedures to support complex coordination patterns.     

Freely Chosen Index Finger Tapping Frequency Is Increased in Repeated Bouts of Tapping

Healthy individuals (n = 40) performed index finger tapping at freely chosen frequency during repeated bouts and before and after near-maximal muscle action consisting of 3 intense flexions of the index finger metacarpal phalangeal joint. One experiment showed, unexpectedly, that a bout of tapping increased the tapping frequency in the subsequent bout. Thus, a cumulating increase of 8.2 ± 5.4% (p < .001) occurred across 4 bouts, which were all separated by 10 min rest periods. Follow-up experiments revealed that tapping frequency was still increased in consecutive bouts when rest periods were extended to 20 min. Besides, near-maximal muscle activation, followed by 5 min rest, did not affect the tapping frequency. In conclusion, freely chosen tapping frequency was increased in repeated bouts of tapping, which were separated by 10–20 min rest periods. The observed phenomenon is suggested to be termed repeated bout rate enhancement.     

Sensorimotor coordination generates extended agency

When we synchronize finger tapping with a visual metronome, we experience a strikingly robust phenomenon of extended agency known as Spizzo’s effect. This effect is the compelling sense that we are controlling the metronome. The effect arises even though the agent knows that the metronome operates autonomously. We propose that the extended agency here established over metronome pulses results from sensorimotor coordination. To test this hypothesis, we operationalize sensorimotor coordination in terms of the correlation structures in series of asynchronies or reaction times from two finger-tapping tasks. Analyses reveal that, whereas correlation structures vary across individuals and show a systematic drift towards nonstationarity with increasing metronome frequency conditions, the presence of correlation structure is co-extensive with Spizzo’s effect. We interpret this result as supporting the view that extended agency relies on sensorimotor coordination. Sensorimotor coordination, we suggest, may induce the effect by integrating the perception of visual pulses and the agency over tapping into a synesthetic experience.     

Effect of Object and Task Properties on Bimanual Transport

The use of both hands simultaneously when manipulating objects is fairly commonplace, but it is not known what factors encourage people to use two hands as opposed to one during simple tasks such as transport. In particular, we are interested in three possible transport strategies: unimanual transport, handing off between hands, and symmetric bimanual transport. In this study, we investigate the effect of object size, weight, and starting and ending position (configuration) as well as the need to balance the object on the use of these three strategies in a bowl-moving task. We find that configuration and balance have a strong effect on choice of strategy, and size and weight have a weaker effect. Hand-offs are most often used when the task requires moving an object from left to right and vice versa, while the unimanual strategy was frequently used when passing front to back. The bimanual strategy is only weakly affected by configuration. The need to balance an object causes subjects to favor unimanual and bimanual strategies over the hand-off. In addition, an analysis of transport duration and body rotation suggests that strategy choice may be driven by the desire to minimize body rotation.     

Why might language and motor impairments occur together?

A step‐wise methodology is employed in order to identify common neurological factors underlying motor and language impairments where they occur together. A sample of 15 5–10‐year‐old children with predetermined language impairment was tested comprehensively using the Illinois Test of Psycholinguistic Ability (ITPA) and the Movement Assessment Battery for Children (Movement ABC). On the basis of these tests, only four of the sample were found to have generally poor performance both in psycholinguistic (particularly indexed by problems with visual closure and sound blending) and motor abilities (particularly indexed by manual dexterity problems—bimanual co‐ordination and drawing—and static balance. Further detailed examination of the findings fostered a number of plausible hypotheses to account for this communality. The viability of these different alternatives is discussed. Copyright © 2003 John Wiley & Sons, Ltd.