The effect of movement amplitude and target diameter on reaction time

Henry's (Henry & Rogers, 1960) memory drum model of neuromotor reaction, which predicts an increased response latency for more complicated movements, was tested by examining the effects of variations in movement amplitude and target diameter on choice RT. RT tended to increase with decreasing target diameter, and varied as a U-shaped function with amplitude. Such findings were in only partial support of the memory of drum notion. The data were discussed in relation to information processing, muscle activation, and subjects' expectations for executing responses along the range of movement amplitude.     

The effect of movement amplitude and target diameter on reaction time: comments on Siegel (1977)

Siegel's (1977) interpretation that his reaction time results were solely a function of response factors (movement amplitude and target diameter) was discussed and criticized. It was argued that Siegel's interpretation was inappropriate because stimulus factors (eccentric and visual angle) and response factors were confounded. It was also argued that the surprising U-shaped relation between reaction time and movement amplitude was probably the result of the confounding between stimulus and response factors.     

Modeling rhythmic interlimb coordination: The roles of movement amplitude and time delays

Rhythmic interlimb coordination is characterized by attraction to stable phase and frequency relations. Sudden transitions between the resulting coordination patterns, which are observed when movement frequency is gradually increased, have been modeled at two formally related levels: a potential function and a system of coupled oscillators. At the latter level of the model, two alternative derivations resulted in different predictions with respect to the way in which movement frequency and amplitude affect pattern stability. Our recent results contradicted the prevailing version of the model, which predicts that the influence of movement frequency is fully mediated by the associated changes in amplitude. Although the results could be reconciled with the alternative derivation of the model in which time delays (possibly related to neurophysiological delays) were incorporated, the absence of amplitude-mediated effects on pattern stability challenges both versions of the model. It is argued that by studying coordination dynamics at the level of the potential function as well as at the level of coupled oscillators, new insights into the way in which control parameters influence pattern dynamics may be obtained. This may open up ways to link the coordination dynamics to specific characteristics of the movements of the limbs and the way in which they interact.PsycINFO classification: 2300; 2330     

The effect of prediction accuracy on choice reaction time

In this study, we examined the effect of prediction accuracy on reaction time (RT). Subjects performed on three blocks of choice RT trials, all of which involved the mapping of four stimuli (red, green, 1, or 0) onto two response keys. The subjects were told that the four stimuli were equally probable and that their task was to respond to each stimulus onset by pressing the correct key. In one block (stimulus-prediction), the subjects predicted, prior to each trial, the precise stimulus that would appear. In a second block (category-prediction), the subjects predicted the category of the stimulus (i.e., color or digit) that would appear. In a third block (no-prediction), the subjects simply responded to each stimulus without making a prior prediction. In the stimulus-prediction block, RT was faster for correct predictions than for incorrect predictions. In addition, RT was faster on trials in which an incorrect prediction involved the correct category than on trials in which it involved the incorrect category: that is, a "half-wrong" prediction was better than an "all-wrong" prediction. In the category-prediction block, RT was faster when the stimulus category was predicted correctly than when it was not. There was little evidence of a response-facilitation contribution to the correct-prediction effect. These results permit inferences concerning the encoding and organization of information in memory.     

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.     

Trajectory evolution and changes in the structure of movement amplitude time series

With increases in the index of difficulty [ID = log₂(2A/W)], the time-series structure of movement amplitude values shift from pink to white noise. The appearance of pink noise at low-ID levels may be attributed to the dominance of feedforward control processes, while the appearance of white noise at high-ID levels may be attributed to increased reliance on visuomotor feedback processes needed to guide movement into the target region. Such within-movement corrections may disrupt the pink-noise time-series correlations that exist in the absence of feedback processing. In our prior work, movement amplitude was defined as the distance moved from movement start until its end. In contrast, in the current study we examined the time-series structure of movement amplitude values at each of 10 different percentages of time into the movement trajectory—ranging between 10 and 100% of the movement time (%MT)—at a low (2 bits) and a high (5 bits) ID level. We hypothesized that at both ID levels a pink-noise time-series structure would be seen during the early portions of the movement trajectory when feedforward control should dominate, but during later portions of the trajectory, increased whitening of time-series structure would emerge only under ID 5 as there would be an increased need to engage visuomotor feedback processes. Under ID 2, the same level of pink noise should be maintained across all %MT levels as movement should be under the same level of feedforward control throughout the trajectory. The only unpredicted result occurred at ID 2 where the pink-noise level increased with increases in %MT. We hypothesize that such strengthening of pink noise as a function of %MT reflects the engagement of early trajectory corrections superimposed on the initial feedforward signal, but, once such initial adjustments were made, feedforward processes increasingly took over as the trajectory neared its goal.     

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.     

Sequential predictability effects on initiation time and movement time for adults and children

First-grade children and adults performed a two-choice initiation-time/ movement-time task in which signals were (a) more likely to repeat than alternate, (b) more likely to alternate than repeat or (c) equally likely to alternate or repeat. Sequential predictability influenced initiation time but not movement time for adults and for children. These results do not support the suggestion (Wickens, 1974) that sequential predictability affects initiation time and movement time for children but only initiation time for adults. Adults and first graders did differ in their response to repeated events. Adults averaged faster initiation time for alternated than repeated responses and children averaged faster initiation time for repeated than alternated responses.     

The effect of amplitude modulation on intelligibility of time-varying sinusoidal speech in children and adults

Although researchers are currently studying auditory object formation in adults, little is known about the development of this phenomenon in children. Amplitude modulation has been suggested as one of the characteristics of the speech signal that allows auditory grouping. In this experiment, we evaluated children (4 to 13 years of age) and adults to examine whether children's ability to use amplitude modulation (AM) in perception of time-varying sinusoidal (TVS) sentences is different from that of adults, and whether there are developmental changes. We evaluated performance on recognition of TVS sentences (unmodulated, amplitude-comodulated at 25, 50, 100, and 200 Hz, and amplitude-modulated using conflicting frequencies). Overall, the youngest children performed more poorly than did older children and adults. However, difference scores, defined as the percentage of phonemes correct in a given modulation condition minus the percentage correct for the unmodulated condition, showed no significant effects of age. Unlike the findings of previous studies (Carrell & Opie, 1992), these results support the ability of modulation with conflicting frequencies to improve intelligibility. The present study provides evidence that children and adults receive the same benefits (or decrements) from amplitude modulation.     

Timing and accuracy of visually directed movements in children: control of direction and amplitude components

The reaction times (RTs), movement times (MTs), and final accuracy of hand movements directed towards visual goals were measured in 6-, 8-, and 10-year-old children, using tasks in which direction and amplitude components of movement were distinctly required. The tasks were performed with and without visual feedback of the limb. RTs decreased with age, and were shorter in directional than in amplitude task, in all ages. MTs were the longest at age 8 in both tasks, equally short at ages 6 and 10 in the directional task, the shortest at age 10, and intermediate at age 6, when amplitude had to be regulated. In the amplitude task, the target distance generally affected MTs under both visual conditions, but to a lower degree at age 10 than in the two younger groups. Movement accuracy, which was in all cases higher with visual feedback, showed different developmental trends among the two spatial components: directional accuracy was not different among the three groups of age, whereas amplitude accuracy showed a nonmonotonic development in the nonvisual condition, with an increase between age 6 and age 10, and the lowest level at age 8. In the visual condition, amplitude accuracy did not change with age. The specification of direction seems therefore to predominantly load the preparatory stage of the response. Amplitude specification seems to be more dependent on on-going regulations and to undergo a longer and more complex development, with a critical period around age 8 when a greater propensity for a feedback-based control appears on the two components. With increasing age, amplitude tends to be specific to a greater extent by a feedforward process.     

The effect of encoding time on retention by infants and young children

Using a Visual Recognition Memory (VRM) procedure, we examined the effect of encoding time on retention by 1- and 4-year olds. Irrespective of age, shorter familiarization time reduced retention, and longer familiarization time prolonged retention. The amount of familiarization that yielded retention after a given delay decreased as a function of age.     

Anticipation of tennis-shot direction from whole-body movement: The role of movement amplitude and dynamics

While recent studies indicate that observers are able to use dynamic information to anticipate whole-body actions like tennis shots, it is less clear whether the action’s amplitude may also allow for anticipation. We therefore examined the role of movement dynamics and amplitude for the anticipation of tennis-shot direction. In a previous study, movement dynamics and amplitude were separated from the kinematics of tennis players’ forehand groundstrokes. In the present study, these were manipulated and tennis shots were simulated. Three conditions were created in which shot-direction differences were either preserved or removed: Dynamics-Present–Amplitude-Present (D^PA^P), Dynamics-Present–Amplitude-Absent (D^PA^A), and Dynamics-Absent–Amplitude-Present (D^AA^P). Nineteen low-skill and 15 intermediate-skill tennis players watched the simulated shots and predicted shot direction from movements prior to ball-racket contact only. Percent of correctly predicted shots per condition was measured. On average, both groups’ performance was superior when the dynamics were present (the D^PA^P and D^PA^A conditions) compared to when it was absent (the D^AA^P condition). However, the intermediate-skill players performed above chance independent of amplitude differences in shots (i.e., both the D^PA^P and D^PA^A conditions), whereas the low-skill group only performed above chance when amplitude differences were absent (the D^PA^A condition). These results suggest that the movement’s dynamics but not their amplitude provides information from which tennis-shot direction can be anticipated. Furthermore, the successful extraction of dynamical information may be hampered by amplitude differences in a skill-dependent manner.     

Co-regulation of movement speed and accuracy by children with heavy prenatal alcohol exposure

The study investigated how children with heavy prenatal alcohol exposure regulate movement speed and accuracy during goal-directed movements. 16 children ages 7 to 17 years with confirmed histories of heavy in utero alcohol exposure, and 21 nonalcohol-exposed control children completed a series of reciprocal tapping movements between two spatial targets. 5 different targets sets were presented, representing a range of task difficulty between 2 and 6 bits of information. Estimates of percent error rate, movement time, slope, and linear fit of the resulting curve confirmed that for goal-directed, reciprocal tapping responses, performance of the group with prenatal alcohol exposure was described by a linear function, as predicted by Fitts' law, by sacrificing movement accuracy. The index of performance was the same for the two groups: it initially increased, then leveled off for more difficult movements.     

Scaling movement amplitude: adaptation of timing and amplitude control in a bimanual task

Participants traced two circles simultaneously and the diameter of one circle was scaled as the diameter of the other circle remained constant. When the scaled circle was larger, amplitude error shifted from overshooting to undershooting, while shifting from undershooting to overshooting when this circle was smaller. Asymmetric coordination was unstable when the left arm traced a circle larger than the right arm, yet stable when the left arm traced a smaller circle. When producing symmetric coordination and the left arm traced the larger circle, relative phase shifted by 30°, but a right arm lead predominated. When the left arm traced the smaller circle and symmetric coordination was required, a 30° shift in relative phase occurred, but hand lead changed from left to right. The modulation of movement amplitude and relative phase emerged simultaneously as a result of neural crosstalk effects linked to initial amplitude conditions and possibly visual feedback of the hands' motion.     

The contribution of peripheral and central vision in the control of movement amplitude

Past research has revealed that central vision is more important than peripheral vision in controlling the amplitude of target-directed aiming movements. However, the extent to which central vision contributes to movement planning versus online control is unclear. Since participants usually fixate the target very early in the limb trajectory, the limb enters the central visual field during the late stages of movement. Hence, there may be insufficient time for central vision to be processed online to correct errors during movement execution. Instead, information from central vision may be processed offline and utilised as a form of knowledge of results, enhancing the programming of subsequent trials. In the present research, variability in limb trajectories was analysed to determine the extent to which peripheral and central vision is used to detect and correct errors during movement execution. Participants performed manual aiming movements of 450 ms under four different visual conditions: full vision, peripheral vision, central vision, no vision. The results revealed that participants utilised visual information from both the central and peripheral visual fields to adjust limb trajectories during movement execution. However, visual information from the central visual field was used more effectively to correct errors online compared to visual information from the peripheral visual field.     

The attentional cost of amplitude and directional requirements when pointing to targets

The aim of this study was to investigate the comparative cost of accuracy constraints in direction or amplitude for movement regulation. The attentional cost is operationally defined as the amount of disturbance created in a secondary task by the simultaneous execution of a pointing task in direction or amplitude. The cost is expressed in terms of modifications in response to a secondary task, consisting of a foot-pedal release in response to an auditory stimulus (probe). The probe was introduced during the programming portion or the first, middle, or last portion of the pointing movement. The independent variables were the requirements of the task: direction or amplitude, and the moments of occurrence of the probe. Subjects were submitted to eight experimental conditions: (1) simple foot reaction time to a buzzer; (2) single directional task; (3) single amplitude task; (4) dual directional task (i.e. directional task with probe); (5) dual amplitude task (i.e. amplitude task with probe); (6) retest of foot simple reaction time; (7) retest of single directional task; and (8) retest of single amplitude task. Regulation in direction was more attention-demanding than regulation in distance in terms of programming. During pointing in amplitude, probe RT increased monotonically from start to end of movement execution, whereas directional pointing did not lead to any significant probe RT changes. These results emphasize the specific attentional loads for directional and amplitude pointing tasks, hence the involvement of different central nervous system mechanisms for the programming and regulation of the directional and amplitude parameters of pointing movements.     

The role of working memory capacity in implicit and explicit sequence learning of children: Differentiating movement speed and accuracy

This study investigated the role of working memory capacity on implicit and explicit motor sequence learning in young children. To this end, a task was utilized that required a gross motor response (flexing the elbow) and that could differentiate between movement speed (i.e., reaction time and movement time) and movement accuracy. Children aged 7–9 years practiced a serial reaction time task that involved the production of a fixed sequence of elbow flexions of prescribed magnitude across two consecutive days. Children in the explicit group were informed about the presence of the sequence and were shown this sequence, while children in the implicit group were not made aware of the sequence. Additionally, children's verbal and visuospatial working memory capacity was assessed. Results of day 1 regarding movement speed revealed no evidence of sequence learning for either group, but movement accuracy results suggested that sequence learning occurred for the implicit group. For both groups, only improvements in movement accuracy were consolidated on day 2, indicating both general and sequence specific learning. Working memory capacity did not correlate with learning in either of the groups. Children in the explicit group accumulated more sequence knowledge compared to children in the implicit group, but this knowledge did not translate to more or better sequence learning. The minimal differences found between the implicit and explicit condition and the absence of a role for working memory capacity add to the increasing evidence that the observed differences between implicit and explicit sequence learning in adults may be less distinct in children.