The relation between hand movements and intellectual activity in a skilled task

The experiment continues an investigation (Vince, 1953) into the relation between intellectual processes and hand movements in a sensori-motor task. Subjects were required to trace a repeating pattern of circles which appeared one, two or three at a time in a slit. Only one circle at a time could be hit and subjects were instructed to discover for themselves a good path for joining the maximum possible number of circles. The experimental situation thus allowed for various levels of response: pursuit movements, predictive movements, choice and a change of plan. At the end of the experiment subjects were asked to draw their idea of the pattern.

The results support others obtained earlier in showing that in this situation the subject's idea of the pattern he is tracing is determined by his total (motor, as well as visual) response to it. In addition, there was evidence that in some cases improvements occurred in the sensori-motor performance which were not reflected immediately in the subjects' idea of the pattern.     

Unilateral vs. bilateral coordination of circle-drawing tasks

The number of joint motions available in the upper extremity provides for multiple solutions to the coordination of a motor task. Making use of these abundant joint motions provides for task flexibility. Controlling bimanual movements poses another level of complexity because of possible tradeoffs between coordination within a limb and coordination between the limbs. We examined how flexible patterns of joint coordination were used to stabilize the hand's path when drawing a circle independently compared to a bimanual pattern. Across-trial variance of joint motions was partitioned into two components: goal-equivalent variance (GEV), representing variance of joint motions consistent with a stable hand path and non-goal-equivalent variance (NGEV) representing variance of joint motions that led to deviations of the hand's path. GEV was higher than NGEV in both unimanual and bimanual drawing, with one exception. Both GEV and NGEV, related to control of the individual hands' motion, decreased when engaged in the bimanual compared to unimanual drawing. Moreover, NGEV, leading to variability in the vectorial distance between the hands, was higher when the two hands drew circles in a bimanually asymmetric vs. symmetric pattern, consistent with reported differences in the relative phasing of the two hands. Our results suggest that the nervous system controls the individual hands' motions by separate intra-limb synergies during both unimanual and bimanual drawing, and superimposes an additional synergy to achieve stable relative motion of the two hands during bimanual drawing.     

Relationship between directionality and orientation in drawings by young children and adults

The present study examined the relationship between directionality of drawing movements and the orientation of drawn products in right-handed adults and young children for 27 Japanese kindergartners and 29 Japanese university students who were asked to draw with each hand fishes in side view and circles from several starting points. Significant values of chi2 for distributions of frequencies of orientation of the fish drawings and the direction of circular drawing movement indicated that adult right-handers drawing the fish facing to the left tended to draw a circle clock-wise when they drew with the dominant hand, while there was no such significant relationship in young children's drawings. This result may suggest that the reading and writing habits may be implicated in the direction of drawing movements with the dominant hand, and this directional bias of drawing movement in the dominant hand can appear in the orientation of finished drawings.     

Perceptual asymmetry for chimeric faces across the life span

Perceptual asymmetries for processing chimeric faces were investigated in dextral subjects, ranging in age from 5 years to elderly adults. The task involved deciding which member of a pair of face chimeras presented in free vision looks happier, the one with the smile to the left or its mirror image with the smile to the right (Levy, Heller, Banich, & Burton, 1983a, Brain and Cognition, 2, 404-419). A leftward bias was found for all age groups. However, kindergarteners' mean asymmetry score was lower than that of all other groups combined, most likely due to noise in their data. The direction in which subjects drew circles with their left and right hands was also observed as an index of interhemispheric communication. All groups showed a bias toward drawing the circles in concordant directions except the kindergarteners. The relation between subjects' performance on the circle drawing and facebook tasks is discussed.     

Vision,proprioception and corollary discharge in a movement recall test

Movement recall was investigated in relation to the sensory processes involved in a triangle drawing task.Forty subjects in two groups, one with and one without visual feedback, performed a recall task involving movements of their index finger. All subjects attended different experimental sessions in which (1) all proprioceptive feedback was eliminated by the ischaemic block technique, (2) muscle spindle feedback was distorted by vibration of the muscles and tendons involved in the movement, and (3) proprioceptive feedback was normal.Within each session subjects were required firstly to recall triangular movements made for them passively by the experimenter, and secondly, to recall movements they had made actively. Results indicated comparable accuracy in recall of active movements in all conditions, and a decrement in passive recall dependent on the availability of the alternative sources of feedback. The results indicated a process of integrated contribution of all inputs to the perception of movement; redundancy in information when all channels are available; and a role of corollary discharge in recall of movements.     

A quantitative evaluation of the AVITEWRITE model of handwriting learning

Much sensory-motor behavior develops through imitation, as during the learning of handwriting by children. Such complex sequential acts are broken down into distinct motor control synergies, or muscle groups, whose activities overlap in time to generate continuous, curved movements that obey an inverse relation between curvature and speed. The adaptive vector integration to endpoint handwriting (AVITEWRITE) model of Grossberg and Paine (2000) [A neural model of corticocerebellar interactions during attentive imitation and predictive learning of sequential handwriting movements. Neural Networks, 13, 999-1046] addressed how such complex movements may be learned through attentive imitation. The model suggested how parietal and motor cortical mechanisms, such as difference vector encoding, interact with adaptively-timed, predictive cerebellar learning during movement imitation and predictive performance. Key psychophysical and neural data about learning to make curved movements were simulated, including a decrease in writing time as learning progresses; generation of unimodal, bell-shaped velocity profiles for each movement synergy; size scaling with isochrony, and speed scaling with preservation of the letter shape and the shapes of the velocity profiles; an inverse relation between curvature and tangential velocity; and a two-thirds power law relation between angular velocity and curvature. However, the model learned from letter trajectories of only one subject, and only qualitative kinematic comparisons were made with previously published human data. The present work describes a quantitative test of AVITEWRITE through direct comparison of a corpus of human handwriting data with the model's performance when it learns by tracing the human trajectories. The results show that model performance was variable across the subjects, with an average correlation between the model and human data of 0.89+/-0.10. The present data from simulations using the AVITEWRITE model highlight some of its strengths while focusing attention on areas, such as novel shape learning in children, where all models of handwriting and the learning of other complex sensory-motor skills would benefit from further research.     

The Dynamics of Bimanual Circle Drawing

A bimanual circle drawing task was employed to elucidate the dynamics of intralimb and interlimb coordination. Right-handed subjects were required to produce circles with both hands in either a symmetrical (mirror) mode (i.e. one hand moving clockwise, the other counter-clockwise) or in an asymmetrical mode (i.e. both hands moving clockwise or counter-clockwise). The frequency of movement was scaled by an auditory metronome from 1.50 Hz to 3.25 Hz in8 (8-sec) steps.In the asymmetrical mode,distortions ofthe movement trajectories, transient departures from the target pattern of coordination, and phase wandering were evident as movement frequency was increased. These features suggested loss of stability. Deviations from circular trajectories were most prominent for movements of the left hand. Transient departures from the required mode of coordination were also largely precipitated by the left hand. The results are discussed with reference to manual asymmetries and mechanisms of interlimb and intersegmental coordination.     

Matching of Movements Made Independently by the Two Arms in Normal Humans

Comparisons were made of voluntary movements of the right and left arms in normal human subjects. A series of movements of different amplitudes, made at the subject’s own speed, was performed with one limb. After a rest period, the same series was repeated with the contralateral limb. The relation between movement peak velocity and movement amplitude was linear and was the same for both arms. With repeated testing over periods up to two months, the slope of the peak velocity—amplitude relation decreased during the first week, thereafter remaining unchanged. In a second series of experiments, six normal subjects continuously wore a 1 lb (0.45 kg) weight strapped to their left (non-dominant) forearm for up to 1 week. This resulted in an increase in the slope of the peak-velocity/amplitude relation in this arm. A parallel change occurred in movements made independently by the right (non-loaded) arm. A similar matching of movement performance of the two limbs was seen following removal of the weight. The data is interpreted as providing support for the hypothesis that there is a single movement “command” which is applied to both limbs. The interaction of this command with the limbs which have similar second-order mechanical properties yields similar movements even when they are made independently.     

Matching of movements made independently by the two arms in normal humans

Comparisons were made of voluntary movements of the right and left arms in normal human subjects. A series of movements of different amplitudes, made at the subject' own speed, was performed with one limb. After a rest period, the same series was repeated with the contralateral limb. The relation between movement peak velocity and movement amplitude was linear and was the same for both arms. With repeated testing over periods up to two months, the slope of the peak velocity-amplitude relation decreased during the first week, thereafter remaining unchanged. In a second series of experiments, six normal subjects continuously wore a 1 lb (0.45 kg) weight strapped to their left (non-dominant) forearm for up to 1 week. This resulted in an increase in the slope of the peak-velocity/amplitude relation in this arm. A parallel change occurred in movements made independently by the right (non-loaded) arm. A similar matching of movement performance of the two limbs was seen following removal of the weight. The data is interpreted as proving support for the hypothesis that there is a single movement "command" which is applied to both limbs. The interaction of this command with the limbs which have similar second-order mechanical properties yields similar movements even when they are made independently.     

Perceiving one’s own movements when using a tool

The present study examined what participants perceive of their hand movements when using a tool. In the experiments different gains for either the x-axis or the y-axis perturbed the relation between hand movements on a digitizer tablet and cursor movements on a display. As a consequence of the perturbation participants drew circles on the display while their covered hand movements followed either vertical or horizontal ellipses on the digitizer tablet. When asked to evaluate their hand movements, participants were extremely uncertain about their trajectories. By varying the amount of visual feedback, findings indicated that the low awareness of one’s own movements originated mainly from an insufficient quality of the humans’ tactile and proprioceptive system or from an insufficient spatial reconstruction of this information in memory.     

Does handedness determine which hand leads in a bimanual task?

Right- and left-handers (n = 16 in each group) were tested on a bimanual circle task that required drawing either in the same direction (parallel) or in a mirror symmetrical coordination mode with the two hands. The authors' primary purposes were to examine the effect of circle direction on within-hand and between-hands variables and to determine whether the relation between hand lead and coordination mode (parallel or mirror symmetrical) differs for left- and right-handers. A strong relation was found between lead hand and movement condition, which depended on the direction of the movements and whether the task was parallel or mirror symmetrical. The pattern of results was similar for left- and right-handers on parallel tasks, but group differences were found with respect to mirror symmetrical tasks. At odds with the general claim that the dominant hand leads, the present results indicated that hand dominance does not generally determine which hand leads.     

Does Handedness Determine Which Hand Leads in a Bimanual Task?

Right- and left-handers (n = 16 in each group) were tested on a bimanual circle task that required drawing either in the same direction (parallel) or in a mirror symmetrical coordination mode with the two hands. The authors' primary purposes were to examine the effect of circle direction on within-hand and between-hands variables and to determine whether the relation between hand lead and coordination mode (parallel or mirror symmetrical) differs for left- and right-handers. A strong relation was found between lead hand and movement condition, which depended on the direction of the movements and whether the task was parallel or mirror symmetrical. The pattern of results was similar for left-and right-handers on parallel tasks, but group differences were found with respect to mirror symmetrical tasks. At odds with the general claim that the dominant hand leads, the present results indicated that hand dominance does not generally determine which hand leads.     

The effect of discordant sensory information in graphic production: two distinct subject groups

The present study investigated the underlying processes used to cope with discordant sensory information induced in a mirror-drawing task. Two experiments were carried out in which adults copied simple geometrical figures made up of either horizontal and vertical segments or oblique segments meeting at a right angle in both a normal and a mirror condition. Experiment 1 identified individual differences in relation to preferred graphic movement directions; some subjects preserved the visual directions that occurred in normal drawing by reversing the direction of drawing movements (perceived-direction group), while others preserved normal drawing directions that produced reversed visual directions (performed-direction group). Experiment 2 was performed to elucidate whether these two distinct behaviors resulted from different strategies used to cope with visuo-proprioceptive discordances. The main results showed that preference for the perceived directions led to longer pauses, slower movement velocity, greater movement dysfluency, and greater spatial orientation accuracy. By contrast, longer reaction time and greater angular accuracy characterized performance in the performed-direction group. These results were interpreted as indicating that two distinct information-processing strategies can be used when resolving sensory discordance in graphic production.     

Coordination dynamics and attentional costs of continuous and discontinuous bimanual circle drawing movements

It has been suggested that the temporal control of rhythmic unimanual movements is different between tasks requiring continuous (e.g., circle drawing) and discontinuous movements (e.g., finger tapping). Specifically, for continuous movements temporal regularities are an emergent property, whereas for tasks that involve discontinuities timing is an explicit part of the action goal. The present experiment further investigated the control of continuous and discontinuous movements by comparing the coordination dynamics and attentional demands of bimanual continuous circle drawing with bimanual intermittent circle drawing. The intermittent task required participants to insert a 400ms pause between each cycle while circling. Using dual-task methodology, 15 right-handed participants performed the two circle drawing tasks, while vocally responding to randomly presented auditory probes. The circle drawing tasks were performed in symmetrical and asymmetrical coordination modes and at movement frequencies of 1Hz and 1.7Hz. Intermittent circle drawing exhibited superior spatial and temporal accuracy and stability than continuous circle drawing supporting the hypothesis that the two tasks have different underlying control processes. In terms of attentional cost, probe RT was significantly slower during the intermittent circle drawing task than the continuous circle drawing task across both coordination modes and movement frequencies. Of interest was the finding that in the intermittent circling task reaction time (RT) to probes presented during the pause between cycles did not differ from the RT to probes occurring during the circling movement. The differences in attentional demands between the intermittent and continuous circle drawing tasks may reflect the operation of explicit event timing and implicit emergent timing processes, respectively.     

Characterization of fine motor development: Dynamic analysis of children’s drawing movements

In this study, we investigated children’s fine motor development by analyzing drawing trajectories, kinematics and kinetics. Straight lines drawing task and circles drawing task were performed by using a force sensitive tablet. Forty right-handed and Chinese mother-tongue students aged 6–12, attending classes from grade 1 to 5, were engaged in the experiment. Three spatial parameters, namely cumulative trace length, vector length of straight line and vertical diameter of circle were determined. Drawing duration, mean drawing velocity, and number of peaks in stroke velocity profile (NPV) were derived as kinematic parameters. Besides mean normal force, two kinetic indices were proposed: normalized force angle regulation (NFR) and variation of fine motor control (VFC) for circles drawing task. The maturation and automation of fine motor ability were reflected by increased drawing velocity, reduced drawing duration, NPV and NFR, with decreased VFC in circles drawing task. Grade and task main effects as well as significant correlations between age and parameters suggest that factors such as schooling, age and task should be considered in the assessment of fine motor skills. Compared with kinematic parameters, findings of NFR and VFC revealed that kinetics is another important perspective in the analysis of fine motor movement.     

Perceptual learning in visual category acquisition

The attribute structure of a set of dot patterns was studied by having subjects segment (parse) the dots of each pattern into parts or subunits by drawing circles around groups of dots from each pattern. These parsing data were obtained for subjects who had no prior experience with the patterns and for subjects who had previously learned to identify the patterns as members of one of four categories. Analyses of the parsing data indicated that category learning increased the salience of large subunits that were similar in orientation for patterns that were members of the same category. This evidence for perceptual learning was obtained even when the category training procedure required learning to identify the patterns individually, suggesting that attribute abstraction and item learning are not incompatible. It was also obtained without an increase in overall intersubject agreement. The latter result led us to question the usefulness of intersubject agreement as an index of category knowledge.     

Asynchrony in discrete bimanual aiming: Evidence for visual strategies of coordination

The bimanual coupling literature supposes an inherent drive for synchrony between the upper limbs when making discrete bimanual movements. The level of synchrony is argued to be task dependent, reliant on the visual demands of the two targets, and the result of a complex pattern of hand and eye movements (Bingham, Hughes, & Mon-Williams, 2008 ; Riek, Tresilian, Mon-Williams, Coppard, & Carson, 2003 ). However, recent work by Bruyn and Mason ( 2009 ) suggests that temporal coordination is not solely influenced by visual saccades. In this experimental series, a total of 8 participants performed congruent movements to targets either near or far from the midline. Targets far from the midline, requiring a visual saccade, resulted in greater terminal asynchrony. Initial and terminal asynchrony were not consistent, but linked to the task demands at that stage of the movement. If the asynchrony evident at the end of a bimanual movement is due to a complex pattern of hand and eye movements then the removal of visual feedback should result in an increase in synchrony. Sixteen participants then completed congruent and incongruent bimanual aiming movements to near and/or far targets. Movements were made with or without visual feedback of hands and targets. Analyses revealed that movements made without visual feedback showed increased synchrony between the limbs, yet movements to incongruent targets still showed greater asynchrony. We suggest that visual constraints are not the sole cause of asynchrony in discrete bimanual movements.     

The effect of perceptual-motor continuity compatibility on the temporal control of continuous and discontinuous self-paced rhythmic movements

One of the questions yet to be fully understood is to what extent the properties of the sensory and the movement information interact to facilitate sensorimotor integration. In this study, we examined the relative contribution of the continuity compatibility between motor goals and their sensory outcomes in timing variability. The variability of inter-response intervals was measured in a synchronization-continuation paradigm. Participants performed two repetitive movement tasks whereby they drew circles either using continuous or discontinuous self-paced movements while receiving discrete or continuous auditory feedback. The results demonstrated that the effect of perceptual-motor continuity compatibility may be limited in self-paced auditory-motor synchronization as timing variability was not significantly influenced by the continuity of the feedback or the continuity compatibility between feedback and the movement produced. In addition, results suggested that the presence of salient perceptual events marking the completion of the time intervals elicited a common timing process in both continuous and discontinuous circle drawing, regardless of the continuity of the auditory feedback. These findings open a new line of investigation into the role of the discriminability and reliability of the event-based information in determining the nature of the timing mechanisms engaged in continuous and discontinuous self-paced rhythmic movements.     

Comfortable synchronization of cyclic drawing movements with a metronome

Continuous circle drawing is considered a paragon of emergent timing, whereas the timing of finger tapping is said to be event-based. Synchronization with a metronome, however, must to some extent be event-based for both types of movement. Because the target events in the movement trajectory are more poorly defined in circle drawing than in tapping, circle drawing shows more variable asynchronies with a metronome than does tapping. One factor that may have contributed to high variability in past studies is that circle size, drawing direction, and target point were prescribed and perhaps outside the comfort range. In the present study, participants were free to choose most comfortable settings of these parameters for two continuously drawn shapes, circles and infinity signs, while synchronizing with a regular or intermittently perturbed metronome at four different tempi. Results showed that preferred circle sizes were generally smaller than in previous studies but tended to increase as tempo decreased. Synchronization results were similar for circles and infinity signs, and similar to earlier results for circles drawn within a fixed template (Repp & Steinman, 2010). Comparison with tapping data still showed drawing to exhibit much greater variability and persistence of asynchronies as well as slower phase correction in response to phase shifts in the metronome. With comfort level ruled out as a factor, these differences can now be attributed more confidently to differences in event definition and/or movement dynamics.     

目标大小变化对多目标视觉追踪的影响

采用多目标追踪任务（MOT）对追踪过程中被试（16名）的眼动进行记录,探讨目标特征变化对视觉追踪的影响。结果表明：视觉追踪机制能够对物体的特征属性进行编码加工,但加工程度受制于目标物与分心物之间的特征竞争关系;追踪过程中,视觉系统采用知觉组织加工策略,以被追踪目标构成的多边形中心为注意中心;物体大小特征没有引起较多的外源性注意,在物体大小特征的变化条件下,视觉追踪主要是内源性的注意控制加工过程。