The study examined symmetrical bimanual coordination of children with spastic hemiparetic cerebral palsy (SHCP) and a typically developing (TD) control group under conditions of visual feedback created by placing a glass screen, opaque screen or a mirror (“mirror box”) between the arms. The “mirror box” creates a visual illusion, which gives rise to a visual perception of a zero lag, symmetric movement between the two arms. Children with SHCP exhibited a similar mean coordination pattern as the TD control group, but had greater movement variability between the arms. Furthermore, movement variability in children with SHCP was significantly greater in the screen condition compared with the glass and mirror condition, which were similar to each other. The effects of the availability of visual feedback in individuals with hemiparesis are discussed with reference to central and peripheral mechanisms.
Max G. Feltham, Annick Ledebt, Simon J. Bennett, Frederik J.A. Deconinck, Martine H.G. Verheul and Geert J.P. Savelsbergh
Eryk P. Przysucha and M. Jane Taylor
The purpose of this study was to compare the postural sway profiles of 20 boys with and without Developmental Coordination Disorder (DCD) on two conditions of a quiet standing task: eyes open and eyes closed. Anterior-posterior (AP) sway, medio-lateral sway (LAT), area of sway, total path length, and Romberg’s quotient were analyzed. When visual information was available, there was no difference between groups in LAT sway or path length. However, boys with DCD demonstrated more AP sway (p < .01) and greater area of sway (p < .03), which resulted in pronounced excursions closer to their stability limits. Analysis of Romberg’s quotient indicated that boys with DCD did not over-rely on visual information.
James W. Roberts, James Lyons, Daniel B. L. Garcia, Raquel Burgess and Digby Elliott
The multiple process model contends that there are two forms of online control for manual aiming: impulse regulation and limb-target control. This study examined the impact of visual information processing for limb-target control. We amalgamated the Gunslinger protocol (i.e., faster movements following a reaction to an external trigger compared with the spontaneous initiation of movement) and Müller-Lyer target configurations into the same aiming protocol. The results showed the Gunslinger effect was isolated at the early portions of the movement (peak acceleration and peak velocity). Reacted aims reached a longer displacement at peak deceleration, but no differences for movement termination. The target configurations manifested terminal biases consistent with the illusion. We suggest the visual information processing demands imposed by reacted aims can be adapted by integrating early feedforward information for limb-target control.
William M. Land, Gershon Tenenbaum, Paul Ward and Christian Marquardt
Attunement to visual information has been suggested to mediate the performance advantage associated with adopting an external focus of attention (e.g., Al-Abood, Bennett, Moreno Hernandez, Ashford, & Davids, 2002; Magill, 1998). We tested this hypothesis by examining the extent to which online visual information underpins the external focus advantage. The study examined skilled golfers on a putting task under one of three attentional focus conditions: control (no instructions), irrelevant (tone counting), and external (movement effect focus), with either full or occluded vision. In addition to task performance, the effect of attentional focus and vision on between-trial movement variability was examined. We found a significant advantage for an external focus of attention in the absence of vision. The results of the movement variability analysis further indicated that external focus was not mediated by the online use of vision. We discuss these findings in the context of traditional cognitive perspectives to external focus effects.
Birgit Rösblad and Claes von Hofsten
Are children with developmental coordination disorders (DCD) more dependent on vision for constructing movements than children without DCD? How important is visual feedback of the hand and how important is visual specification of the goal in this respect? These questions were studied in 10 children with DCD, 3 girls and 7 boys, ranging in age between 7 and 16 years. Each child was matched against a child of the same sex and age without DCD. The task was to pick beads, one at a time, from one cup and carry them to another cup. With the aid of a mirror arrangement and a curtain, visual information about the performing hand and the cups and beads was manipulated. The movements were monitored with an optoelectronic device (SELSPOT II). The results showed that the children with DCD made movements that were both slower and much more variable than those of their age-matched peers, The withdrawal of visual information affected both groups of children in similar ways. However, one boy with developmental disorders revealed a remarkable decrease in performance when the task was carried out without visual information of either the hand or the cups and beads.
Pirjo Kejonen, Kari Kauranen, Ahti Niinimaa and Heikki Vanharanta
Balance evaluation and training are typically included in rehabilitation after sport injuries.
To evaluate and compare the maximal velocities and accelerations of balancing movements during 2-leg stance with eyes open and closed. The effect of age on the measured values was also evaluated.
100 healthy, randomly selected subjects (50 men, 50 women; age 31–80 years).
Body-movement values were measured with the Mac Reflex motion-analysis system.
Subjects stood barefoot.
Main Outcome Measures:
ANOVAs were used to explain the body movements. The location of measurement, presence or absence of vision, and subjects’ age and gender were used as explanatory variables.
With eyes closed, all measured body parts had significantly higher maximal velocity and acceleration values than with eyes open. Age seemed to affect the acceleration values.
Visual information was found to significantly influence movement values. Exercises should be done under various conditions to improve standing balance abilities.
Dominique van Roon, Bert Steenbergen and Ruud G.J. Meulenbroek
People with cerebral palsy (CP) are known to rely heavily on visual guidance when making targeted upper-limb movements. In the present study, we examined whether being able to visually monitor the moving limb forms a precondition for people with CP to make accurate upper-limb movements. Eight participants with tetraparetic CP and eight controls were asked to produce large-amplitude, straight-line drawing movements on a digitizing tablet. In half the trials, vision of the moving limb was blocked. Accuracy constraints were manipulated by varying the width of the target and by imposing a maximum width of the movement path. Surprisingly, when vision was blocked movement accuracy was comparable in the two groups. Thus, people with tetraparetic CP do not strictly require constant vision of their moving limb to make accurate upper-limb movements. They compensated for the lack of visual information, however, by prolonging movement time. Using a high pen force proved a general strategic adaptation, possibly to filter out unwanted noise from the motor system or to enhance proprioceptive input.
Deborah Dewey and Lawrence R. Brawley
A major research limitation in investigating the validity of the TAIS has been the failure to distinguish when attentional style has an effect on the information processing system, early as in encoding or late after processing. Few investigations have examined the TAIS predictive validity in a controlled setting wherein task attention demands can be systematically and accurately varied. Does the general trait of attentional style really have anything to do with how attention related information is processed? The present study examined this question using a valid attention theory (Treisman's feature integration theory) and a visual search paradigm. When the TAIS attentional-style scales were correlated with visual search rate for attention demanding targets, no significant relationships were observed. Specifically, TAIS scales did not relate to visual search rate for an attention demanding target, the performance of subjects extreme in search rate, or the central to peripheral slowing of search time in target detection. The factorial validity of the TAIS was also questioned. It was concluded that the attentional-style scales were not valid in predicting how attention related visual information is processed. The importance of distinguishing when attentional style might be operating in the information processing system was emphasized for future research.
Veerle Puttemans, Sophie Vangheluwe, Nicole Wenderoth and Stephan P. Swinnen
When performing movements with different spatial trajectories in both upper limbs simultaneously, patterns of interference emerge that can be overcome with practice. Even though studies on the role of augmented feedback in motor learning have been abundant, it still remains to be discovered how overcoming such specific patterns of spatial interference can be optimized by instructional intervention. In the present study, one group acquired a bimanual movement with normal vision, whereas a second group received augmented feedback of the obtained trajectories on a computer screen in real time. Findings revealed that, relative to normal vision, the augmented feedback hampered skill learning and transfer to different environmental conditions. These observations are discussed in view of the benefits and pitfalls of augmented feedback in relation to task context and instructional condition.
Matheus M. Gomes and José A. Barela
The purpose of this study was to examine the effects of visual and somatosensory information on body sway in individuals with Down syndrome (DS). Nine adults with DS (19–29 years old) and nine control subjects (CS) (19–29 years old) stood in the upright stance in four experimental conditions: no vision and no touch; vision and no touch; no vision and touch; and vision and touch. In the vision condition, participants looked at a target placed in front of them; in the no vision condition, participants wore a black cotton mask. In the touch condition, participants touched a stationary surface with their right index finger; in the no touch condition, participants kept their arms hanging alongside their bodies. A force plate was used to estimate center of pressure excursion for both anterior-posterior and medial-lateral directions. MANOVA revealed that both the individuals with DS and the control subjects used vision and touch to reduce overall body sway, although individuals with DS still oscillated more than did the CS. These results indicate that adults with DS are able to use sensory information to reduce body sway, and they demonstrate that there is no difference in sensory integration between the individuals with DS and the CS.