Does motor programming necessitate response execution?

The complexity of a movement is known to affect the time it takes to initiate the movement. This effect is thought to reflect changes in the duration of processes that operate on a motor program. This question addressed here is whether programming a movement compels the start of its overt execution. If it does, then the programming processes may be said to occur after the "point of no return." We report results from an empirical procedure and a theoretical analysis designed to study processes before and after this point separately. According to our results, changes in the complexity of a movement affect only the prior set of processes. From this we argue that motor programming does not necessitate response execution and that the point of no return occurs very late in the information-processing system. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Optimality in human motor performance: Ideal control of rapid aimed movements.

A stochastic optimized-submovement model is proposed for Fitts' law, the classic logarithmic trade-off between the duration and spatial precision of rapid aimed movements. According to the model, an aimed movement toward a specified target region involves a primary submovement and an optional secondary corrective submovement. The submovements are assumed to be programmed such that they minimize average total movement time while maintaining a high frequency of target hits. The programming process achieves this minimization by optimally adjusting the average magnitudes and durations of noisy neuromotor force pulses used to generate the submovements. Two new experiments on rapid wrist rotations yield additional support for the stochastic optimized-submovement model. Experiment 1 revealed that the mean durations of primary submovements and of secondary submovements, not just average total movement times, conform to a square-root approximation of Fitts' law derived from the model. Also, the spatial endpoints of primary submovements have standard deviations that increase linearly with average primary-submovement velocity, and the average primary-submovement velocity influences the relative frequencies of secondary submovements, as predicted by the model. During Experiment 2, these results were replicated and extended under conditions in which subjects made movements without concurrent visual feedback. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Distributional analysis and De Jong, Liang, and Lauber's (1994) dual-process model of the Simon effect.

R. De Jong et al (1994) proposed a dual-process model to account for the Simon effect and its reversal. Their proposal included a distributional analysis whose results, they claimed, support the time-course assumptions they make for the 2 processes of the model. It is shown that the 2 functional components of the dual-process model, the unconditional and conditional automaticity, are equivalent to earlier accounts of the Simon effect and its reversal, namely automatic response activation of the dimensional overlap model (S. Kornblum et al, 1990) and logical recoding (A. Hedge & N. W. A. Marsh, 1975), respectively. It is also shown that the distributional analysis is a simple computational procedure that reflects fundamental statistical properties of the underlying RT distributions and their interrelationships and that the time-course assumptions by De Jong et al precluded at least half of these interrelationships. Indeed, experimental results from tasks in which the Simon effect is obtained often violate these assumptions, as is demonstrated in this article. Finally, it is also shown that the data by De Jong et al are consistent with the hypothesis that the Simon effect and its reversal can be accounted for by a common mechanism with 2 independent functional components. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Design of an Automatic Teller Machine with Esterel Studio

This paper describes how the cash-point service can be specified and simulated using Esterel Studio. Received July 2000 / Accepted in revised form December 2000     

Eye-hand coordination: Oculomotor control in rapid aimed limb movements.

Three experiments are reported in which Ss produced rapid wrist rotations to a target while the position of their eyes was being monitored. In Experiment 1, Ss spontaneously executed a saccadic eye movement to the target around the same time as the wrist began to move. Experiment 2 revealed that wrist-rotation accuracy suffered if Ss were not allowed to move their eyes to the target, even when visual feedback about the moving wrist was unavailable. In Experiment 3, wrist rotations were equally accurate when Ss produced either a saccadic or a smooth-pursuit eye movement to the target. However, differences were observed in the initial-impulse and error-correction phases of the wrist rotations, depending on the type of eye movement involved. The results suggest that aimed limb movements use information from the oculomotor system about both the static position of the eyes and the dynamic characteristics of eye movements. Furthermore, the information that governs the initial impulse is different from that which guides final error corrections. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neuronal correlates of sensorimotor association in stimulus–response compatibility.

Neuronal mechanisms underlying stimulus–response (S-R) associations in S-R compatibility tasks were identified in 2 experiments with monkeys. Visual stimuli were presented on the left and right calling for left–right movements under congruent and incongruent S-R mapping instructions. High- and low-pitched tones calling for left–right movements were presented to the left and right ear, and the stimulus side was irrelevant. Single neurons sensitive to the S-R mapping rule were found in the primary motor cortex. The large overlap between the neuronal populations sensitive to the stimulus side, the S-R mapping rule, and the response side, respectively, is consistent with the idea that sensory-to-motor transformation is a continuous rather than a discrete process. Results partly support the hypothesis that the increase in reaction time with incongruent mapping is caused by the automatic activation of the congruent, but erroneous, response. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Catheter Flow Probe for Measurement of Left Ventricular Source Parameters

A balloon-tip electromagnetic velocity flow probe was used to measure source pressure Pg and zero-load aortic flow Qs in seven mongrel dogs before and after coronary artery ligation, where Qs is the expected aortic flow at zero aortic input impedance and Pg is the expected left ventricular pressure for the open-circuit condition of the equivalent model of the left ventricle. The source parameters Pg and Qs were measured by two types of flow probes (cuff-type and catheter-tip flow probe). The source parameters measured by the cuff-type flow probe are designated by Pg and Qs, and Pgv and Vs are source parameters measured by the catheter probe. The correlation coefficient between the mean values of Pg and Pgv was 0.83 in 47 measurements, and correlation between Q5 and Vs was 0.64. After coronary artery ligation, Qs, Pg, Pgj,, and Vs decreased by 35.9, 19.87, 16.67, and 2.6 percent, respectively. A change of 10 to 30 percent in aortic input resistance could be produced by balloon inflation in two consecutive heartbeats. This paper presents a new application of a catheter flow probe for diagnosis of cardiac pump performance during catheterization procedures.     

Cooperation,scale-invariance and complex innovation systems: a generalization

Scientometrics - The focus of this paper is the question “Can scale-invariant properties of collaborative research activities of a complex innovation system be quantified, modeled and used to...