Examining age-related movement representations for sequential (fine-motor) finger movements

Theory suggests that imagined and executed movement planning relies on internal models for action. Using a chronometry paradigm to compare the movement duration of imagined and executed movements, we tested children aged 7-11 years and adults on their ability to perform sequential finger movements. Underscoring this tactic was our desire to gain a better understanding of the age-related ability to create internal models for action requiring fine-motor movements. The task required number recognition and ordering and was presented in three levels of complexity. Results for movement duration indicated that 7-year-olds and adults were different from the other groups with no statistical distinction between 9- and 11-year-olds. Correlation analysis indicated a significant relationship between imagined and executed actions. These results are the first to document the increasing convergence between imagined and executed movements in the context of fine-motor behavior; a finding that adds to our understanding of action representation in children.     

Increasing convergence between imagined and executed movement across development: evidence for the emergence of movement representations

Motor imagery (MI) has become a principal focus of interest in studies on brain and behavior. However, changes in MI across development have received virtually no attention so far. In the present study, children (N = 112, 6 to 16 years old) performed a new, computerized Virtual Radial Fitts Task (VRFT) to determine their MI ability as well as the age‐related confluence between performance in executed and imagined movement conditions. Participants aimed at five targets, which were positioned along radial axes from a central target circle. The targets differed in width (2.5, 5, 10, 20 or 40 mm), resulting in an index of difficulty (ID) that varied from 6.9 to 2.9 bits. Performance was indexed by the linear relationship between ID and Movement Time (MT). The findings showed that executed task performance was slower than imagined performance. Moreover, conformance to Fitts’ Law during executed movement performance was obtained from a very young age. Most importantly, correlations between imagined and executed movements were low in the young participants but gradually increased across age. These age‐related changes in MI are hypothesized to reflect the children's emerging ability to represent internal models for prospective actions, consistent with the gradual unfolding of feedforward control processes.     

Deficits in executed and imagined aiming performance in brain-injured children

Motor disorders are a frequent consequence of acquired brain injury (ABI) in children and much effort is currently invested in alleviating these deficits. The aim of the present study was to test motor imagery (MI) capabilities in children with ABI (n=25) and an age- and gender-matched control group (n=25). A computerized Virtual Radial Fitts Task (VRFT) was used to investigate the speed-accuracy trade-offs (or Fitts' law) that occur as target size is varied for both executed and imagined performance. In the control group, the speed for accuracy trade-off for both executed and imagined performance conformed to Fitts' law. In the ABI group, only executed movements conformed to Fitts' law. These findings suggest that children with ABI show an inferior ability to imagine the time needed to complete goal-directed movements with differential difficulty levels.     

When music tempo affects the temporal congruence between physical practice and motor imagery

When people listen to music, they hear beat and a metrical structure in the rhythm; these perceived patterns enable coordination with the music. A clear correspondence between the tempo of actual movement (e.g., walking) and that of music has been demonstrated, but whether similar coordination occurs during motor imagery is unknown. Twenty participants walked naturally for 8 m, either physically or mentally, while listening to slow and fast music, or not listening to anything at all (control condition). Executed and imagined walking times were recorded to assess the temporal congruence between physical practice (PP) and motor imagery (MI). Results showed a difference when comparing slow and fast time conditions, but each of these durations did not differ from soundless condition times, hence showing that body movement may not necessarily change in order to synchronize with music. However, the main finding revealed that the ability to achieve temporal congruence between PP and MI times was altered when listening to either slow or fast music. These data suggest that when physical movement is modulated with respect to the musical tempo, the MI efficacy of the corresponding movement may be affected by the rhythm of the music. Practical applications in sport are discussed as athletes frequently listen to music before competing while they mentally practice their movements to be performed.     

Hand differences in pegboard performance through development

Handedness is often measured by comparing the relative performance of the two hands on a given task, such as peg moving. Studies of the development of manual skill have typically found that the difference between the hands for a peg-moving task does not fluctuate with age. The current study was conducted to examine age-related changes in manual performance, on the standard Annett pegboard. Ninety-eight right-handed individuals ranging in age from 5 to 24 performed three trials on the pegboard with each hand. Performance with each hand was reflected in movement time and as a laterality quotient. Analyses revealed a right-hand advantage in performance which was larger in the younger than the older participants. The smaller hand difference in the older participants appeared due to greater changes in performance with the non-preferred hand as a function of age.     

The development of hand preference in children: The effect of task demands and links with manual dexterity

Lateralisation of hand preference and manual dexterity are known to develop over childhood, while in adulthood strength of hand preference has been shown to interact with extrinsic task demands. Some evidence exists to suggest that strength of hand preference and motor skill may be related. In the current study a handedness inventory, midline crossing (QHP) and peg-moving tasks were used to investigate: (1) the development of hand preference between 4 and 11 years; (2) whether extrinsic task demands affect strength of hand preference, and (3) whether strength of hand preference was associated with manual dexterity. Younger children (4–5 years) showed weak hand preference in comparison to older children (8–11 years), and extrinsic task demands influenced willingness to cross the body’s midline with the preferred hand. Age and peg-moving speed were associated with midline crossing in certain task conditions. Overall, results suggest a coupling between manual dexterity and brain maturation in typical development.     

The acquisition of bimanual coordination is mediated by anisotropic coupling between the hands

The present study was designed to test two predictions from the coupled oscillator model of multifrequency coordination. First, it was predicted that multifrequency tasks that match the inherent manual asymmetry (i.e., the preferred hand assigned to the faster tempo) would be easier to learn than tasks that do not match the inherent dynamics (i.e., the non-preferred hand assigned to the faster tempo). Second, in the latter case acquisition of the multifrequency coordination would involve a reorganisation of the coupling dynamics such that the faster hand would exert a greater influence on the slower hand than vice versa. Sixteen right-handed volunteers received extensive training on a 2:1 coordination pattern involving a bimanual forearm pronation-supination task. Participants were randomly assigned to one of two groups: 1L:2R in which the preferred right hand performed the higher frequency, or 2L:1R in which the non-preferred left hand performed the higher frequency. The dynamic stability of the patterns was assessed by the ability of participants to maintain the coordination pattern as movement frequency was increased. Changes in the directional coupling between the hands was assessed by transition pathways and lead-lag relationship evident in a 1:1 anti-phase frequency-scaled coordination task performed prior to and following three practice sessions of the 2:1 task. The predicted differential stability between the multifrequency patterns was evident in the initial acquisition sessions but by the end of training the two patterns evidenced equivalent stability. Unexpectedly, for both groups the fast hand displayed greater variability in amplitude and movement frequency than the slow hand perhaps reflecting anchoring afforded to the slow hand by synchronising movement endpoints with the auditory pacing metronome. Analysis of pre- to post-training changes to the coupling dynamics in the 1:1 anti-phase task support the hypothesis that acquisition of the 2L:1R pattern involved reorganisation of the inherent dynamics.     

The influence of task paradigm on motor imagery ability in children with Developmental Coordination Disorder

Children with Developmental Coordination Disorder (DCD) have difficulty imagining movements such that they conform to the customary temporal constraints of real performance. We examined whether this ability is influenced by the choice of task used to elicit motor imagery (MI). Performance of typically developing (TD) (n = 30) and children with DCD (n = 30) was compared on two tasks: the Visually Guided Pointing Task (VGPT) and the Computerized Virtual Radial Fitts Task (C-VRFT). Since the VGPT places higher demands on executive functions like working memory but requires less spatial planning, we reasoned that the C-VRFT would provide a purer measure of motor imagery (or simulation). Based on our earlier work, we predicted that imagery deficits in DCD would more likely manifest on the C-VRFT. Results showed high correlations between tasks in terms of executed and imagined movement time suggest that both tasks measure MI ability. However, group differences were more pronounced in the imagined condition of the radial Fitts’ task. Taken together, the more spatially complex C-VRFT appears to be a more sensitive measure of motor imagery, better discriminating between DCD and TD. Implications for theory and practice are discussed.     

Are Fast Complex Movements Unimaginable? Pupillometric Studies of Motor Imagery in Expert Piano Playing

Motor imagery (MI; mental simulation of actions) shares certain mental representations and processes with executed movement (ME). This neurocognitive overlap between MI and ME may explain why the systematic use of MI improves skilled performance in numerous domains. Unfortunately, the attentional mechanisms underlying MI remain unresolved. Therefore, the present studies investigated the role of attentional effort (as measured by pupil dilation) in MI. We evaluated the effects of movement complexity and speed on expert pianists' pupil dilation as they physically executed and used MI to perform easy/complex and slow/fast music phrases. Results revealed that easy movements required similar levels of attentional effort during MI and ME. However, during complex movements performed at a fast speed, the correspondence between execution and imagery of movement was disrupted.     

The control of movement in the preferred and non-preferred hands

The nature of the difference in skill between the preferred and non-preferred hands was investigated using a peg-board task. The first experiment examined the effects of varying movement amplitude and target tolerance on performance. The difference between hands was found to be related to tolerance rather than movement amplitude. The second study analysed a film record of well-practised subjects, confirming the hypothesis that most of the difference between hands is due to relative slowness of the non-preferred hand in the positioning phase involving small corrective movements. Analysis of the type and number of errors further suggested that this result is not due to differences in duration of movements but to their increased frequency, implying greater accuracy of aiming with the preferred hand. Thus whilst the initial gross analysis implicated feedback processing in skill differences the more detailed analysis suggests that motor output of the nonpreferred hand is simply more variable.     

Proactive and retroactive transfer of middle age adults in a sequential motor learning task

We assessed the effects of aging in the transfer of motor learning in a sequential manual assembly task that is representative for real working conditions. On two different days, young (18–30 years) and middle-aged adults (50–65 years) practiced to build two products that consisted of the same six components but which had to be assembled in a partly different order. Assembly accuracy and movement time during tests, which were performed before and after the practice sessions, were compared to determine proactive and retroactive transfer.     

Motor learning without physical practice: The effects of combined action observation and motor imagery practice on cup-stacking speed

In this study we explored training effects for combined action observation and motor imagery (AO + MI) instructions on a complex cup-stacking task, without physical practice. Using a Graeco-Latin Square design, we randomly assigned twenty-six participants into four groups. This counterbalanced the within-participant factor of practice condition (AO + MI, AO, MI, Control) across four cup-stacking tasks, which varied in their complexity. On each of the three consecutive practice days participants experienced twenty trials under each of the three mental practice conditions. On each trial, a first-person perspective video depicted bilateral cup-stacking performed by an experienced model. During AO, participants passively observed this action, responding only to occasional colour cues. For AO + MI, participants imagined performing the observed action and synchronised their concurrent MI with the display. For MI, a sequence of pictures cued imagery of each stage of the task. Analyses revealed a significant main effect of practice condition both at the ’surprise’ post-test (Day 3) and at the one-week retention test. At both time points movement execution times were significantly shorter for AO + MI compared with AO, MI and the Control. Execution times were also shorter overall at the retention compared with the post-test. These results demonstrate that a complex novel motor task can be acquired without physical training. Practitioners can therefore use AO + MI practice to supplement physical practice and optimise skill learning.     

Abnormalities of motor and praxis imagery in children with DCD

In an earlier study using the visually guided pointing task (VGPT) the authors showed that the timing of imagined movement sequences in children with developmental coordination disorder (DCD) does not conform to the conventional speed-for-accuracy trade-off (or Fitts' law [P.M. Fitts, Journal of Experimental Psychology 47 (1954) 381-391]) that occurs when the distance and accuracy requirements of movements are varied [P. Maruff, P.H. Wilson, M. Trebilcock, J. Currie, Neuropsychologia 37 (1999b) 1317-1324]. The present study sought to replicate this earlier finding and to examine (using a weight manipulation) whether this deficit was also attributable to inaccurate programming of relative force. The chronometry of real and imagined movements was investigated in a group of 20 children with DCD aged between 8 and 12 years and a group of controls matched on age and verbal IQ (VIQ). Movement duration was tested for real and imagined movements using the preferred hand, with the VGPT performed under two load conditions: with and without the addition of a weight attached to a pen. Group means of each subjects' mean movement duration were calculated and plotted against target width for each of the four conditions [Movement type (2) x Load (2)] and a logarithmic curve was fitted to the data points. In the control group, the speed-for-accuracy trade-off for both real and imagined performance conformed to Fitts' law under each load condition. In the DCD group only real movements conformed to Fitts' law. Moreover, the effect of load differed between groups--for real movements, movement duration did not differ between load and no-load conditions for either group, while for imagined movements, movement duration increased under the load condition for the control group only. These results replicate and extend the results of our earlier study. This pattern of performance suggests that children with DCD have an impairment in the ability to generate internal representations of volitional movements which may reflect an impaired ability to process efference copy signals. The ability to programme both relative force and timing appears to underly this difficulty. Results have implications for the use of (guided) motor imagery training in order to facilitate the development of motor skill in children with DCD.     

Gender-Specific Movement Strategies Using a Computer-Pointing Task

Females typically demonstrate a movement time advantage for tasks requiring high levels of manual dexterity, whereas males are notably better at targeting activities. According to D. Kimura (2000), the hunter-gatherer hypothesis primarily accounts for those performance advantages; that dichotomy fails, however, when one makes movement outcome predictions for tasks that are not clearly fine-motor or interceptive in nature. Investigators have recently proposed that time constraints (M. Peters, 2005) and gender-specific response style differences (M. Peters & P. Campagnaro, 1996; L. E. Rohr, 2006) affect motor performance. Here, the author used a computer-pointing task measuring both movement error and movement time in 16 participants to further investigate response style differences. Kinematic and linear regression analyses between resultant error and both movement time and task difficulty reinforced the notion that gender-specific movement biases emphasize speed and accuracy, respectively, for men and women.     

Gender-specific movement strategies using a computer-pointing task

Females typically demonstrate a movement time advantage for tasks requiring high levels of manual dexterity, whereas males are notably better at targeting activities. According to D. Kimura (2000), the hunter-gatherer hypothesis primarily accounts for those performance advantages; that dichotomy fails, however, when one makes movement outcome predictions for tasks that are not clearly fine-motor or interceptive in nature. Investigators have recently proposed that time constraints (M. Peters, 2005) and gender-specific response style differences (M. Peters & P. Campagnaro, 1996; L. E. Rohr, 2006) affect motor performance. Here, the author used a computer-pointing task measuring both movement error and movement time in 16 participants to further investigate response style differences. Kinematic and linear regression analyses between resultant error and both movement time and task difficulty reinforced the notion that gender-specific movement biases emphasize speed and accuracy, respectively, for men and women.     

An especial skill: Support for a learned parameters hypothesis

We tested the ‘learned parameters’ hypothesis as an explanation of the ‘especial skill effect’. Outcome attainment and movement kinematics were recorded for 10 expert and 10 novice players performing basketball free-throw shots at five distances (11-19 ft) with a regular and heavy weight basketball. As predicted, experts performed better than expected relative to the regression equation at the 15 ft, free-throw line with the regular basketball, supporting the ‘especial skill effect’. This effect was not present for the experts when shooting with the heavy ball. Novices did not show an advantage at the free-throw line when performing with either ball. Although the outcome attainment scores support the ‘learned parameters’ hypotheses, kinematic analysis failed to identify differences in the movement pattern for the especial skill, suggesting that these skills (i.e., shooting at different distances) are not governed by separate motor programs.     

The theory of intelligence and its measurement

Mental chronometry (MC) studies cognitive processes measured by time. It provides an absolute, ratio scale. The limitations of instrumentation and statistical analysis caused the early studies in MC to be eclipsed by the ‘paper-and-pencil’ psychometric tests started by Binet. However, they use an age-normed, rather than a ratio scale, which severely limits the ability of IQ tests to probe the physical basis of differences in cognition. For this reason, Arthur Jensen reinitiated mental chronometry in the 1970s. He designed an apparatus that measures reaction time to a task known as the Hick paradigm that requires the testee to respond to a display of 1 to 8 lights. Faster decision times were related to psychometric g, with theoretically important consequences. He was able to do this, where many other studies had failed, mainly because his apparatus clearly separated movement (MT) from reaction time (RT, also called ‘decision time’.) Interestingly, while RT is clearly related to IQ, MT is not. Principal components analysis reveals RT to be a cognitive variable and MT a motor variable. Failure to distinguish between them drastically obscures the correlation between composite RT (i.e., RT + MT) and cognitive variables. When Jensen (2006) reviewed the literature on MC he found there was a shocking lack of standardization in the administration, recording, and analysis. Consequently, the results of a study conducted in one lab, even though measured in absolute time, could not be compared directly against those from another. Termed “method variance,” this is a major obstacle to the advancement of MC. For that reason, Jensen's Institute of Mental Chronometry commissioned a leading electronics firm to construct a state-of-the-art apparatus to administer, record, and analyze MC experiments.     

Intellectual ability in young men separated temporarily from their parents in childhood

We examined the effects of early life stress (ELS) on intellectual ability in 2,725 20-year-old male participants, of whom 321 were separated temporarily (mean 1.7 years) from both their parents during World War II, at an average age of 4.3 years. Intellectual ability was tested when entering compulsory military service. The separated men had − 0.28 (95% CI − 0.39, − 0.16), − 0.13 (95% CI − 0.25, − 0.01), − 0.18 (95% CI − 0.29, − 0.06), and − 0.19 (95% CI − 0.30, − 0.07) SD units lower verbal, visuospatial, arithmetic, and composite score of intellectual ability, respectively, compared to non-separated. Participants who were separated for more than a year and between two and four years had the lowest ability scores. ELS showed most consistent associations with verbal ability, but were not limited to it. Children beyond infancy and before their school-age may be the most vulnerable to the adverse effects of the ELS.     

Independent Development of Imagination and Perception of Fitts' Law in Late Childhood and Adolescence

Recent neurophysiological and behavioral research suggests perception-action systems are tightly coupled. Accordingly, Fitts' law has been observed when individuals execute, perceive, and imagine actions. Developmental research has found that (a) children demonstrate Fitts' law in imagined actions and (b) imagined movement time (MT) becomes closer to actual MT as age increases. However, action execution, imagination, and perception have yet to be assessed together in children. The authors investigated how imagined and perceived MTs related to actual MTs in children and adolescents. It was found that imagined MTs were longer than execution MTs were. Perception MTs were lower than execution MTs for children and more consistent with execution MTs for adolescents. These results suggest potential mechanistic differences in action imagination and perception.     

Memory for emotional faces in naturally occurring dysphoria and induced sadness

The aim was to establish if the memory bias for sad faces, reported in clinically depressed patients (Gilboa-Schechtman, Erhard Weiss, & Jeczemien, 2002; Ridout, Astell, Reid, Glen, & O'Carroll, 2003) generalises to sub-clinical depression (dysphoria) and experimentally induced sadness. Study 1: dysphoric (n = 24) and non-dysphoric (n = 20) participants were presented with facial stimuli, asked to identify the emotion portrayed and then given a recognition memory test for these faces. At encoding, dysphoric participants (DP) exhibited impaired identification of sadness and neutral affect relative to the non-dysphoric group (ND). At memory testing, DP exhibited superior memory for sad faces relative to happy and neutral. They also exhibited enhanced memory for sad faces and impaired memory for happy relative to the ND. Study 2: non-depressed participants underwent a positive (n = 24) or negative (n = 24) mood induction (MI) and were assessed on the same tests as Study 1. At encoding, negative MI participants showed superior identification of sadness, relative to neutral affect and compared to the positive MI group. At memory testing, the negative MI group exhibited enhanced memory for the sad faces relative to happy or neutral and compared to the positive MI group. Conclusion: MCM bias for sad faces generalises from clinical depression to these sub-clinical affective states.