Movement time and velocity as determinants of movement timing accuracy

Three experiments investigated the effect of movement time (MT) and movement velocity on the accuracy and initiation of linear timing movements. MTs of 100, 200, 500, 600, and 1000 msec were examined over various distances; timing accuracy decreased with longer MTs and slower average velocities. The velocity effect was independent of MT and occurred when the velocities were above and below about 15 cm/sec. Self-paced initiation times to movement increased directly with MT and inversely as a function of movement velocity. The latency data complement the MT findings in suggesting that average velocity is a key parameter in the initiation and control of discrete timing movements and, that there is some lower velocity below which movement control breaks down.     

The independence of reaction and movement time in programmed movements

The issues of controlled vs automatic processing, and programmed vs preprogrammed movements deal with two problems, whether subjects can control their performance, and whether RT is related to task difficulty. The subjects' control over the relationship of RT and movement was examined. Two experiments are reported in which the relationship between RT and MT is investigated using instructional set and speed-accuracy tradeoff techniques. The two issues considered were: (1) whether subjects could separate their RT and MT in a top-down approach; (2) whether RT could be independent of MT and accuracy. The two experiments separated RT and MT using instructional set and feedback bands in a simple horizontal aiming movement. A relationship was found between RT and movement accuracy. The implications for preprogramming and programming are briefly discussed.     

Movement observation affects movement execution in a simple response task

The present study was designed to examine the hypothesis that stimulus-response arrangements with high ideomotor compatibility lead to substantial compatibility effects even in simple response tasks. In Experiment 1, participants executed pre-instructed finger movements in response to compatible and incompatible finger movements. A pronounced reaction time advantage was found for compatible as compared to incompatible trials. Experiment 2 revealed a much smaller compatibility effect for less ideomotor-compatible object movements compared to finger movements. Experiment 3 presented normal stimuli (hand upright) and flipped stimuli (hand upside-down). Two components were found to contribute to the compatibility effect, a dynamic spatial compatibility component (related to movement directions) and an ideomotor component (related to movement types). The implications of these results for theories about stimulus-response compatibility (SRC) as well as for theories about imitation are discussed.     

Effects of average movement velocity on reaction time and spatiotemporal accuracy in single-aiming and rapid-timing movement tasks

The effects of instructed movement speed were investigated in two experiments. First, rapid-timing and single-aiming movement tasks were compared. Unlike rapid timing, single aiming implies spatial accuracy. The aim of the first experiment was twofold: (a) to examine whether the requirement of accurate placement termination in single aiming affects the negative relationship between instructed average velocity and reaction time found in rapid timing, and (b) to test the speed-accuracy relationships predicted by the symmetric impulse variability model of these movement tasks. For this purpose, four average velocities (5, 24, 75, and 140 cm/s) were investigated in both types of movement tasks in a two-choice reaction task. The effects of average velocity on reaction time were similar in both single-aiming and rapid-timing tasks, and the predicted linear relationship between instructed average velocity and spatial accuracy was not found. The results suggest that the movement control mode, that is, open loop or closed loop, interferes with effects of instructed average velocity. The movement control mode explanation was confirmed in the second experiment with respect to the effect of paired velocities on reaction time. It is argued that the type of movement control mode must be considered in the interpretation of effects of instructed average velocity on reaction time and spatiotemporal measures.     

Effects of mood states and anxiety as induced by the video-recorded stroop color-word interference test in simple response time tasks on reaction time and movement time

Mood states and anxiety might alter performance in complex tasks whereas in more simple tasks such as stimulus-response, high anxiety could provoke bias in mechanisms of attention leading to better performances. We investigated the effects of anxiety, tension, and fatigue induced by the video-recorded Stroop Color-Word Interference Test on either reaction or movement time. 61 subjects performed a visual and an auditory response-time test in Control and Anxiogenic conditions during which heart rate was measured. Tension and anxiety states were assessed using self-evaluation. Analysis showed auditory response time was improved for both reaction and movement times in the Anxiogenic condition. These data suggest that the increased attention underlying anxiety and mood responses could have favored auditory response time by leading subjects to process stimuli more actively. In addition, state-anxiety and tension could have influenced muscular tension, enhancing the movement time in the auditory task.     

Influence of extended practice on programming time, movement time, and transfer in simple target-striking responses

Two experiments describe the effects of extended practice on the development of motor control programs for simple target-striking responses. In Experiment 1,400 right-hand trials of simple one-target and two-target striking tasks were performed. In Experiment 2,600 practice trials were given. Overall reaction time (RT) was faster for the one-target condition in both experiments, supporting a response complexity effect. Movement time (MT) for both conditions improved linearly with practice, suggesting that development of the motor control programs was still occurring. Subjects then transferred to a three-target condition for 50 trials, performing the transfer task with the right hand in Experiment 1, and with right and left hands in Experiment 2. Transfer to the three-target conditions produced execution errors in the form of failure to contact the second target and repetitive tapping on the third target. These results suggest that extensive practice may serve to firmly entrench a response sequence, making it difficult to implement a similar, but unique, motor control program. An interpretation in terms of automaticity and enhanced priming of behavioral and neural pathways is offered to account for these results.     

Controlling velocity in rapid movements

It has often been reported that subjects prefer to use a strategy in which they vary movement velocity and peak amplitude in a linear fashion. In this study, control of velocity and amplitude in rapid reciprocating movements of the interphalangeal joint of the thumb was investigated by examining movement trajectories and patterns of activity in the extensor pollicis longus (EPL) and flexor pollicis longus (FPL) muscles. In controlling either amplitude or peak flexion velocity without constraint, subjects always used a strategy in which peak extension velocity and peak flexion velocity had strong linear correlations with movement amplitude. When they were required to keep either amplitude or peak flexion velocity fixed their movements were still biased toward a strategy in which peak velocity and movement amplitude covaried. It is suggested that the preferred strategy is related to a basic principle of scaling the magnitude and duration of a velocity profile in order to achieve different movement amplitudes.     

Attention demands of movements as a function of their duration and velocity

The attention demands of initiating and controlling discrete movements were examined as a function of their movement time (MT) and average movement velocity. Experiment 1 showed that the attention required to execute a movement decreased as MT decreased, although Experiment 2 through independently manipulating MT and movement velocity, revealed that movement velocity is the key determiner of attention demands rather than MT. The attention demands of preparing a high velocity movement are greater than during its execution with the reverse being the case for relatively slow velocity movements. The results are compatible with the view that it is the initiation of error corrections that are attention demanding (Keele 1973).     

Programming strategies for rapid aiming movements under simple and choice reaction time conditions

Increases in reaction time (RT) as a function of response complexity have been shown to differ between simple and choice RT tasks. Of interest in the present study was whether the influence of response complexity on RT depends on the extent to which movements are programmed in advance of movement initiation versus during execution (i.e., online). The task consisted of manual aiming movements to one or two targets (one- vs. two-element responses) under simple and choice RT conditions. The probe RT technique was employed to assess attention demands during RT and movement execution. Simple RT was greater for the two- than for the single-target responses but choice RT was not influenced by the number of elements. In both RT tasks, reaction times to the probe increased as a function of number of elements when the probe occurred during movement execution. The presence of the probe also caused an increase in aiming errors in the simple but not choice RT task. These findings indicated that online programming was occurring in both RT tasks. In the simple RT task, increased executive control mediated the integration between response elements through the utilization of visual feedback to facilitate the implementation of the second element.     

Programming strategies for rapid aiming movements under simple and choice reaction time conditions

Increases in reaction time (RT) as a function of response complexity have been shown to differ between simple and choice RT tasks. Of interest in the present study was whether the influence of response complexity on RT depends on the extent to which movements are programmed in advance of movement initiation versus during execution (i.e., online). The task consisted of manual aiming movements to one or two targets (one- vs. two-element responses) under simple and choice RT conditions. The probe RT technique was employed to assess attention demands during RT and movement execution. Simple RT was greater for the two- than for the single-target responses but choice RT was not influenced by the number of elements. In both RT tasks, reaction times to the probe increased as a function of number of elements when the probe occurred during movement execution. The presence of the probe also caused an increase in aiming errors in the simple but not choice RT task. These findings indicated that online programming was occurring in both RT tasks. In the simple RT task, increased executive control mediated the integration between response elements through the utilization of visual feedback to facilitate the implementation of the second element.     

Programming time as a function of number of movement parts and changes in movement direction

The question of whether changes seen in simple reaction time (SRT) as a function of response complexity (i.e., number of movement parts) should be considered as differences in the time needed to centrally program a motor response was addressed. Using a large-scale tapping response, 14 subjects contacted from one to five targets positioned in a straight line, while a second group of 14 subjects executed 90 degrees changes in direction in striking the targets. Results revealed that mean SRT and mean premotor time increased linearly as the number of movement parts increased, regardless of whether changes in movement direction had to be programmed, with the greatest increase occurring between one-, and two-part responses. Increases in motor time were not sufficient to account for the sizeable SRT effect. These findings support the position of increased central programming time for more complex responses, and also help establish some of the boundaries of the complexity effect.     

Reaction time and movement time as measures of stimulus evaluation and response processes

Reaction time has been divided into the time to initiate a response (RT) and the time to execute the motor response (MT) in many chronometric studies of intelligence. Our purpose was to determine which cognitive processes are reflected by RT and MT. To accomplish this, the latency of the P300 wave of the event-related potential was recorded concurrently with RT and MT measures in three experiments. P300 latency reflects the duration of stimulus evaluation relatively independently of response processes. In the first experiment, a Sternberg memory task was employed to manipulate stimulus classification requirements. In the second, the subjects' emphasis on either speed or accuracy of responding was examined during a task that also manipulated stimulus evaluation time. In the third experiment, a Stroop-like task was used to examine response processes. RT and P300 latency varied with manipulations of stimulus evaluation time, whereas MT varied with difficulty of motor execution. MT was also affected by stimulus classification processes. Both RT and MT were sensitive to processes involved in response bias and preparation. The possibility that the correlations of RT and MT with measures of intelligence are due to effects on a common stage of information processing cannot be rejected in the light of these results.     

Movement prediction and movement production

The prediction of future positions of moving objects occurs in cases of actively produced and passively observed movement. Additionally, the moving object may or may not be tracked with the eyes. The authors studied the difference between active and passive movement prediction by asking observers to estimate displacements of an occluded moving target, where the movement was driven by the observer's manual action or was passively observed. In the absence of eye tracking, they found that in the active condition, estimates are more anticipatory than in the passive conditions. Decreasing the congruence between motor action and visual feedback diminished but did not eliminate the anticipatory effect of action. When the target was tracked with the eyes, the effect of manual action disappeared. Results indicate distinct contributions of hand and eye movement signals to the prediction of trajectories of moving objects.