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Two experiments were conducted to identify the response elements responsible for the complexity effect found by Henry and Rogers (1960). An attempt was made to determine if these elements were affecting the premotor time component of simple reaction time (SRT). If they were, a strong case could be made for the argument that neuromotor programming time was affected because premotor time is a more exact estimate of it than SRT. The results revealed that premotor time was unaffected by a forward change in movement direction, but increased as the number of movement parts increased from one to two and as the demand for movement accuracy increased. Thus, increasing the (1) number of parts and (2) accuracy demands were identified as elements of response complexity which increase programming time and support Henry and Rogers (1960) hypothesis that the time to initiate a response becomes longer as the programming process become more complex.

The present study sought to determine whether individuals could be trained to attenuate the visual dominance effect by selecting a proprioceptive stimulus for attention. Using a reaction time (RT) task, subjects received either: (a) visual (V), (b) proprioceptive (P), or (c) combined V and P (VP) stimuli during the first four days. Each subject was then tested under all three stimuli conditions. Results showed that reaction time to the P cue was always faster than that to V or combined VP stimuli. The order in which subjects were tested under each stimulus modality significantly affected the results such that those subjects who received initial exposure to the V stimulus produced the slowest premotor time scores but the fastest motor time scores. These results suggest that the nature of the stimulus which initiates the volitional task can affect both the central processing requirements to initiate the response, and the qualitative manner in which the motor command is executed.

The relationship of age and a life style of physical activity with isometric knee extension strength and a simple and choice resisted response time was examined in 60 male subjects divided into four equal groups: Old Active, Old Inactive, Young Active, Young Inactive. Each response measure consisted of a visual reaction time followed by a movement to a target. Reaction time was further fractionated into premotor and motor time components. Resistance was applied in reaction time trials via an electromagnet placed below the subject's heel. Although knee extension strength was lower in old groups, the Old Actives were 7.7 kg stronger than Old Inactives. Simple and choice total reaction time for all groups lengthened in the resisted condition due to an increased motor time component. Even though the resistance applied was a fixed 10% of maximum strength the increase in resisted motor time was greatest for the young groups and unrelated to physical activity level.

It is well documented that simple reaction time (RT) varies inversely with stimulus intensity, but there is disagreement as to which stimulus modality produces the fastest simple RT. An investigation was conducted to equate two stimulus modalities, auditory (A) and electrocutaneous (EC), using varying stimulus intensities in a simple RT protocol. A second investigation was then conducted to examine neuromotor characteristics of stimulus-evoked responses using previously equated A and EC stimuli of varying intensity from the first investigation. Results showed that RT, premotor time (PMT), and motor time (MT) were all inversely related to stimulus intensity, while maximum displacement (MAXD) was directly related to stimulus intensity, and movement time was not affected by stimulus intensity. We conclude that: (a) both central and peripheral components of RT are altered by varying stimulus intensities, and (b) rapid movements are enhanced by increasing stimulus intensity.

Fractionated knee extensor and plantar flexor reaction time (RT) components were assessed in a group of eight weightlifters and eight long distance runners. Following a 4-day period of baseline stabilization for each muscle group, a 50% maximal voluntary contraction (MVC) holding-time exercise was administered. Results showed that the runners had longer premotor times (PMT) than the weightlifters in the knee extensors, but had much faster PMTs than the lifters in the plantar flexor condition. Compared to previously reported investigations using non-athletes, the data for the present sample of athletes indicated faster total reaction times(TRT) in both the knee extensors and the plantar flexors. A resistance of 15% MVC applied during the RT task resulted in a lengthening of the motor time (MT) component in both groups prior to exercise. However, while knee extensor resisted motor time was lengthened by the exercise task, no such lengthening occurred in plantar flexor resisted RT. It is concluded that power-trained and endurance-trained athletes exhibit difference in response to a fractionated RT task, under both baseline and fatiguing exercise conditions.

The purpose of this study was to determine how the manipulation of movement duration affects components of fractionated reaction time and presumably motor programming. Twelve subjects, in a simple reaction time paradigm, responded to an auditory signal by executing an elbow flexion movement in the sagittal plane through a range of motion of 100° in 150, 300, 600 and 1200 ms. Results indicated no changes in motor time but small increments in premotor and reaction time through the 600 ms condition. At 1200 ms, reaction time increased faster than premotor time, and this appeared to be predominantly a consequence of an increment in motor time. These data were interpreted to be supportive of the notion that movement duration is related to response complexity and the time required for motor programming.

The fractionation of a simple right-hand grip total reaction time (RT) into central and peripheral temporal components (premotor and motor time, respectively) helped to define the site of RT change following an auditory induced startle response and two fatiguing hand-grip exercise regiments for eight males and eight females. Following the startle response, mean values for RT significantly lengthened, due primarily to an increase in premotor time. In contrast, lengthened RT following both fatigue regimens (42% and 55% strength decrements) were due to substantial increases in the motor time component. These results suggest that although performance of tasks which demand a high degree of precision, accuracy, and fine motor control may be disrupted by the introduction of such stressors as an induced startle and local muscular fatigue, the neuromuscular mechanisms mediating performance disruption are dissimilar.

The effects of varying fatigue levels on reaction-time components were determined for 20 young, adult males. Each subject squeezed a hand-gripping device until strength decrements of 20, 40, or 60% were recorded; then the subject released his tension and then reacted to an auditory stimulus by gripping as quickly and forcefully as possible. Testing was also conducted under a nonfatigued state, and every subject was tested under all conditions. Total reaction time was divided into (a) a promoter component, the time from the stimulus to an alteration in the EMG of the finger flexors, and (b) a motor component, the time from the change in the EMG to the first sign of tension uptake. Analyses of variance failed to reveal any alterations in either reaction time or promoter time; however, there was a significant (p.05) elongation of motor time when the muscle was fatigued, with motor time tending to increase linearly as fatigue increased. The results suggest that localized fatigue of this nature is primarily of peripheral (muscular) origin.

Simple and choice knee extension response time was measured on four groups of subjects: Old Active, Old Inactive, Young Active, and Young Inactive. Each response measure consisted of total reaction time plus movement time. Total reaction time was further fractionated into premotor time, which represents the central processing component, and motor time, which represents the peripheral muscular component. All simple and choice fractionated response components demonstrated an age-related lengthening with motor time showing the least amount of lengthening. Although activity level enhanced the speed of all components in aged subjects, movement time was affected to the greatest extent and motor time was affected the least. It is particularly noteworthy that (1) motor time is so little influenced by age and level of activity and (2) the deterioration in speed of movement with age is almost completely negated in Old Active subjects. The results suggest that a life style of regular physical activity has a beneficial effect on several aspects of performance, especially in regard to speed of movement.

Two experiments examined the effect of altering the moment of inertia within an anatomical unit on simple reaction time (SRT), premotor time (PMT), and motor time (MOT) during the initiation of a discrete rapid movement. In Experiment 1 (N = 14), moment of inertia of the forearm was increased with the addition of a weighted cuff fastened around the wrist. In Experiment 2 (N = 7), moment of inertia was altered by the addition of a weighted sleeve to the index finger prior to rapid extension of the digit. Results from both experiments were unequivocal. An increase in the moment of inertia resulted in a significant increase in SRT and MOT but had no significant effect on PMT. Within selected anatomical unites (forearm and index finger), an increase in the moment of inertia does not appear to require additional neuromotor programming time but does influence the overall duration of response initiation.

IN the application of motors for specific duty cycles, driving an arbitrary time varying load, affected by nonlinear damping and dry friction, the time response is often quite difficult to determine analytically. In this paper a method is presented that yields a quick graphical answer which avoids all the difficulties that appear in the analytical treatment of the problem.

Ss squeezed a hand grip device to 1 of 3 submaximal tensions, and reacted to either a light (Exp. I, N = 30) or to a buzzer (Exp. II, N = 24) by squeezing as quickly and forcefully as possible. Total RT was the time from stimulus to the change in tension, and this was divided into Premotor RT (stimulus to change in EMG) and Motor RT (change in EMG to change in tension) to determine the locus of changes in Total RT found by Clarke (1968). Whereas Total RT was unaffected by increased pre-tension, Premotor RT shortened and Motor RT lengthened. Partial programming or activation hypotheses were tenable for the Premotor RT changes, whereas changes in the contractile component, but not in the series elastic component, were tenable for the Motor RT changes.

A list of 16 concrete nouns was presented as words or as simple drawings. The Ss either wrote the verbal labels for recalled items or drew simple pictures of them. The results revealed no effects of mode of input or output upon ease of recall. However, more intertrial organization was observed with word-presentation groups, and in later trials, with word recall.

Eight male smokers were tested under 6 conditions comprising the combinations of 200 mg. caffeine or no caffeine, with no cigarette, one 0.3-mg. nicotine cigarette or one 1.3-mg. nicotine cigarette, for decision time and motor time scores on a choice reaction-time task. Heart rate was monitored from a pretest period throughout the session, and hand steadiness measured on repeated occasions. Decision-time scores were significantly decreased by both caffeine and nicotine, but no interaction was found. The high-nicotine cigarette had the greatest effect. Motor time scores were improved by caffeine only. Both caffeine alone and nicotine alone accelerated the heart rate but in combination appeared to have antagonistic effects. Hand steadiness was significantly impaired by both drugs but with no interaction.

A number of factors, including political movements, legal actions, advances in the technology of teaching, and a still-growing understanding of the causes and treatments of autism, have combined to produce a major reversal in professional attitudes toward parents, described in Chapter 1.

The effects of advance information on movement planning in parkinsonism were assessed by means of movement precuing. Using this technique, the response latencies of identical sets of movements were compared across conditions in which the degree and type of advance movement information were manipulated. Specifically, prior information concerning three movement dimensions (the direction and extent of forthcoming movements, as well as the limb to be used) was or was not provided. Eight patients with Parkinson's disease and 8 neurologically normal age-matched controls served as subjects The experiment showed that the elevated reaction times of the parkinsonian subjects are not primarily caused by delays in response selection. Estimates of specification times for each of the three dimensions showed only a modest slowing in parkinsonians. The specification of those movement dimensions unknown before the response signal appears to occur serially, and can occur in a variable order as in normals. Since parkinsonians can initiate movements with shorter latencies when partial or complete information is available, albeit more slowly than normals, we conclude that response selection and specification processes preceding rapid discrete movements are relatively unaffected by the disease. The overall slowness in movement initiation in parkinsonians as compared with normals may in part be caused by excessive delays in motor time and, in general, to those ‘input’ and/or ‘output’ processes which are unaffected by advance information.

Verbal reaction time patterns were compared in aphasic adults presenting anterior and posterior left hemisphere lesions. Reaction Times were measured from simultaneous recording of the subjects' verbal responses and electromy-ographic activity from three oral-facial sites. Total Reaction Time was fractionated into Premotor Time and Motor Time components to assess latencies associated with motor speech planning and execution. The results suggested that only anterior lesions result in deficits in motor speech planning and/or execution while posterior lesion patients perform no differently than normal. The evidence supports traditional concepts regarding apraxia of speech as being associated with frontal lobe lesions.

Microbehavioural analysis of the human button-press response in a choice reaction time task enabled us to observe the traditional components of reaction time performance and also several additional indicators of psychomotor organization. The principal finding reported here is that in normal subjects stimulus conditions of varying difficulty differentially affect segments of the button-press response not ordinarily associated with cognitive demands of the task. This observation suggested the presence of a certain interaction between cognitive demands of the task and the subsequent motor output control. In a comparison of normal elderly and demented subjects, we demonstrated that the slower reaction times of the demented represent a virtual psychomotor disintegration. The apparent disintegration is interpreted as an inability of demented subjects properly to prepare, organize, and execute the response. The degree of disintegration is most evident during the motor time, which represents a transition between resting state and actual response completion.

NAKAMURA, R. and CHIDA, T. How to Use Bilateral Motions in Facilitation Techniques. Tohoku J. exp. Med., 1983, 141(2), 241-242-Influence of contralateral finger motions on ipsilateral finger extension was analyzed in order to explore optimal condition of bilateral motions as a facilitation technique, measuring motor times (MTs) of finger extensor muscles in four conditions; homonymous or non-homonymous as for muscle coupling and simultaneous or successive as for timing of motion-initiation. Compared to unilateral motion, MTs shortened only in bilateral motion with preceding sustained contractions of the contralateral homonymous muscle.

Two experiments investigated the memory drum theory's prediction (Henry & Rogers, 1960) that simple reaction time (SRT) increased with the complexity of the response to be initiated. Experiment 1 (N = 9) matched the Experiment 1, Group 1, SRT condition described by Henry and Rogers. Results of Experiment 1 replicated those of Henry and Rogers and indicated that the memory drum theory's prediction of increased SRT as a function of increased complexity of response was tenable. Experiment 2 (N = 11) tested the effects of anatomical unit, extent and target size on SRT, premotor time, and motor time. The results supported the contention that alternative explanations for SRT were possible. With complexity constant, increases in anatomical unit lead to increases in SRT, but only in the motor time component which indicated electromechanical rather than neuromotor program delays. It is proposed that the increased motor time could be explained by peripheral events such as the duration maximum torque must be applied by the agonist muscle(s) to generate the angular acceleration required to initiate rapid movement. SRT, premotor time, and motor time increased when target size was reduced from 6.35 cm to 79 cm. The increased premotor time could be a function of the determining of new equilibrium points for the elbow joint during response initiation. No effects on SRT were observed for extent.

Surface EMG enabled fractionation of a simple hand grip total reaction time into peripheral and central processing components (motor time and premotor time, respectively). Changes in reaction time components were investigated in 12 female intercollegiate swimmers (bilateral athletes) and 12 female intercollegiate tennis players (unilateral athletes) following a 48% strength decrement induced by serial maximal voluntary isometric contractions (5 sec in duration). Despite significantly greater strength in the dominant arm than in the nondominant arm, there was no difference in fatigue effects between arms. Fatigue increased the premotor component of reaction time significantly, and indirectly the total reaction time, but the motor time remained essentially constant regardless of the type of previous athletic training. This indicated that fatigue impaired central nervous system or myoneural-junction operations rather than the intramuscular ability to initiate force.

The voluntary control of the energy consumption of the muscle is, according to our previous studies, reducible to the number of time periods of the action currents fired into the muscle. This number of periods defines the physical action (energy.time, g·cm2·s–-1) carried by the muscle into the environment during contraction. As the physical action corresponding to one time period can be regarded as constant, the electrical and mechanical phenomena in the muscle can be represented satisfactorily in terms of a vector coordinate system, whose dimensions are the number of discharged motor time periods and the temporal and spatial shifts of the muscle movement. The interrelations of these dimensions were examined in voluntary actions of the abductor of the forefinger (m. interosseus dors. I) in human. The muscle action currents were recorded from non-selective electrodes. It was observed that the duration of contraction and the muscle shortening were both, within certain limits, directly proportional to the number of periods of the motor discharge.

Mixed Martial Arts (MMA) is a multielement combat sport where fighters need to quickly react to an opponent's movements under fatigued conditions. Research indicates that fast reaction time is important in many sports, but the effect of fatigue has shown negative, null, or even positive influences on reaction time. However, few studies have been conducted in a controlled setting, especially using MMA figthers, whose matches are frequently resolved in a split-second. Therefore, this study investigated whether acute neuromuscular fatigue affects reaction and movement times, and their consistency in MMA fighters (N = 45). Before and after an upper-body Wingate test, a simple visual reaction time task was completed. Results showed a significant negative effect of fatigue on the reaction times and their consistency, with longer reactions (1.5% change) and lower consistency (14.7% change) after the Wingate test. Further, greater amounts of fatigue during the Wingate test seemed to negatively affect the consistency of post-Wingate movement time. Due to cumulative fatigue and the dynamic nature of MMA, our data indicate that not only the decrements in aerobic and anaerobic power likely affect a fighter's performance, but their reaction time and motor time may also be compromised during a fight.

SAJIKI, N. and NAKAMURA, R. Motor Time of the Rectus Femoris during Passive Movements. Tohoku J. exp. Med., 1985, 145 (2), 231-232-Motor time (MT) of 10 normal subjects were examined in three conditions: 1) during passive flexion of the knee (PFLX), 2) during passive extension (PEXT), and without passive movement (STAT). Compared to STAT, MTs of PFLX and PEXT were significantly long. MT tended to be shorter, though insignificant statistically, in PFLX than in PEXT. In conclusion, passive movements are influential in changing the physical state of the muscle including both series-elastic and contractile components.

Motor time (MT) of the rectus femoris was measured for seven normal subjects during rapid extension of the knee joint at 60 degrees flexion in the sitting position with and without external loads on the leg. MT prolonged linearly with external load from 0 to 4 kg. Tangent of this linearity, the rate of tension development (RTD), was significantly different from one another of the subjects and was not related to MT without external load. RTD is a relevant index to assess an efficiency of rapid force generation of a muscle.