Left-hand Performance Research Articles

Mirror Writing and Handedness

It has been reported that left-handed subjects are better able to write in mirror-reversed script than right-handers (Tankle & Heilman, 1983). Vaid and Stiles Davis (1989) conducted studies which led them to contradict the supposed superiority of left-handers in this area. In these studies, left as well as right-handed subjects were examined under normal- and mirror-writing conditions. Both examinations included the analysis of writing time and the accuracy of mirror writing (error rates). Using a digitizing tablet, we examined normal- and mirror-writing performance of left-handers, right-handers, and left-handed subjects who habitually write with their right hand. Our results support the finding of Tankle and Heilman (1983) that left-handers perform better in mirror-writing tasks.

Changes in brain activity during motor learning measured with PET: effects of hand of performance and practice.

The aim of this study is to assess brain activity measured during continuous performance of design tracing tasks. Three issues were addressed: identification of brain areas involved in performing maze and square tracing tasks, investigation of differences and similarities in these areas related to dominant and nondominant hand performance, and most importantly, examination of the effects of practice in these areas. A total of 32 normal, right-handed subjects were instructed to move a pen with the dominant right hand (16 subjects) or nondominant left hand (16 subjects) continuously through cut-out maze and square patterns with their eyes closed during a 40-s positron emission tomography (PET) scan to measure regional blood flow. There were six conditions: 1) holding the pen on a writing tablet without moving it (rest condition); 2) tracing a maze without practice; 3) tracing the same maze after 10 min of practice; 4) tracing a novel maze; and tracing an easily learned square design at 5) high or 6) low speed. To identify brain areas generally related to continuous tracing, data analyses were performed on the combined data acquired during the five tracing scans minus rest conditions. Areas activated included: primary and secondary motor areas, somatosensory, parietal, and inferior frontal cortex, thalamus, and several cerebellar regions. Then comparisons were made between right- and left-hand performance. There were no significant differences in performance. As for brain activations, only primary motor cortex and anterior cerebellum showed activations that switched with hand of performance. All other areas, with the exception of the midbrain, showed activations that were common for both right- and left-hand performance. These areas were further analyzed for significant conditional effects. We found patterns of activation related to velocity in the contralateral primary motor cortex, related to unskilled performance in right premotor and parietal areas and left cerebellum, related to skilled performance in supplementary motor area (SMA), and related to the level of capacity at which subjects were performing in left premotor cortex, ipsilateral anterior cerebellum, right posterior cerebellum and right dentate nucleus. These findings demonstrate two important principles: 1) practice produces a shift in activity from one set of areas to a different area and 2) practice-related activations appeared in the same hemisphere regardless of the hand used, suggesting that some of the areas related to maze learning must code information at an abstract level that is distinct from the motor performance of the task itself.

Differences between left- and right-hand reaction time rhythms: indications of shifts in strategies of human brain activity

Reaction time (RT) measurements serve as quantitative indices for pilots' cognitive processes of the brain. To examine if laterality exists in the brain hemispheres we measured, by the use of a Pilot Evaluation System (PES), right- and left-hand performance rhythms as indicative of RT to audible and visual stimuli. The tests included sets of simple tasks and complex ones to which a secondary task composed of audio signals was added. The accuracy of recorded reaction time was 27 ms. Seven right-handed males, 27–42 years of age, experienced with the PES flight simulator, were tested every 2 h, nine times daily (starting at 08:00 h) during 3 consecutive days. The results indicated that for simple tasks, the 24 h period of RT rhythm is either exclusive or prominent for both hands. For complex tasks the prominent period of RT is 24 h for the right (dominant) hand and 8 h for the left (non-dominant) hand (right-hand 24 h period F stat=140, r 2=0.62 and 8 h period F stat=25, r 2=0.22; left-hand 24 h period F stat=44, r 2=0.34 and 8 h period F stat=100, r 2=0.54). The findings suggest that a laterality exists in the brain hemispheres with regard to differences in rhythm periodicities. The expression of this laterality is dependent on the task-load level and points to a strategy of linkage and integrity in brain activity.

Praxis performance with left versus right hemisphere lesions

Praxis is defined as skilled, purposive limb movement. While it has been a consistent finding that lesions of the left cerebral hemisphere result in significantly worse performance on praxis testing than lesions of the right cerebral hemisphere, recently some investigators have proposed that the right hemisphere may also play an important role in mediating praxis. To learn if the right hemisphere does have a role in praxis we studied right-handed patients with right or left hemisphere lesions, as well as right-handed normal controls who were matched for age and education. Two trained raters scored the transitive gesture performance of the forelimb ipsilateral to the injured hemisphere. For the normal controls, left and right hand performances were scored separately and used for statistical comparison. Independent comparisons were made on six dimensions that are important for accurate gesture performance and on an overall apraxia score. When compared to normal control subjects the patients with left hemisphere lesions (LHD) did demonstrate deficient praxis; that is, ideomotor apraxia. However, those with right hemisphere lesions (RHD) did not. Based on this study it would appear that the right hemisphere does not play a crucial role in praxis.

Manual assembly learning and performance of left- and right-handers

This study investigated the learning and performance ability of left-handers in comparison to right-handers in psychomotor tasks. Ten left-handers and 10 right-handers were observed assembling 24 hacksaws and 39 U-bolts and their learning and performance was measured. No significant difference between the performance and learning ability of left-handers in comparison to right-handers was found in either task. Analysis of variance showed that there was significant learning in the first to trials during the U-bolt assembly and in the first five trials during the Hacksaw assembly. The standard deviations for each trial again showed no significant differences between left- and right-handers. A significant decrease in the standard deviation was found in the first three trials of Hacksaw assembly. Left- and righ-handed workers are commonly used in assembly tasks. Previous work has suggested that right-handers may be better in their learning of motor tasks. This research shows that, for real assembly work, there is no difference in performance of left- and right-handed persons, thus no special selection criteria are needed.

Hand, Space and Attentional Asymmetries in Goal-Directed Manual Aiming

Two experiments were conducted to explore the interaction of the two cerebral hemispheres in motor control, by examining hand, space and attentional asymmetries in goal- directed aiming. In Experiment 1, right-handed subjects moved to targets more quickly with their right hand than their left hand. In addition, each hand was faster when moving in its own hemispace. Although in a control condition, movements were initiated more quickly with the left hand, visual distractors disrupted left hand performance more than right hand performance. For contralateral aiming, ipsilateral distractors caused the greatest interference. In Experiment 2, when targets and distractors were all presented at the midline, a right hand advantage was found for movement time along with a left hand advantage for reaction time, independent of target and distractor location. Our findings are discussed in terms of a right hemisphere role in movement preparation and the allocation of attention in space, and greater left hemisphere involvement in movement execution

Movement time of right- and left-handers using their preferred and non-preferred hands

The aim of the present work was to quantify the difference in performance of hands when doing tasks of defined difficulty. Results of five experiments are reported in which strongly lateralised subjects performed movement tasks with their preferred and non-preferred hands. These tasks were: (i) ballistic movements, (ii) Fitts' task, (iii) pin-to-hole transfer, (iv) Drury tracking task, and (v) a modified form of the Drury tracking task in which subjects cut paper with scissors. The results showed that in ballistic tasks there was no significant effect of handedness or of hand used. With visually-controlled tasks, where there was considerable control of accuracy required, the preferred hand generally performed better than the non-preferred hand. There was however no significant difference, in any of the tests, between right- and left-handers when using their preferred hands. Left-handers, in some tasks, performed better with their non-preferred hands than did right-handed persons using the non-preferred hand. Selection of operators for industrial tasks may be dependent on handedness of the person, particularly when machines are designed for a specific handedness. The results of these experiments show that there are no reasons for selection based on inferior performance of left-handers, in fact, left-handers may be superior to right-handers in some respects.

Cortical-cerebellar relationship during continuous motor learning measured by PET

Cortical-cerebellar relationship during continuous motor learning measured by PET H.I. van Mier, J.S. Per lmutter , M.E. Raichle and S.E. Petersen Washington University School of Medicine, Box 8111, St. Louis, MO 63110 Introduction. Data from neurophysiological, neuroanatomical, and lesion studies have suggest the existence of a strong relationship between many areas in the cerebral cortex with different parts of the contralateral cerebellum. We report data from a PET study on motor learning which show distinct functional similarities between sets of cortical and cerebellar regions. Such information could prove to be useful adjunct to connectional studies outlining the relationships between the cortical and cerebellar regions. Methods. We tested 32 normal right handed subjects who moved a pen continuously through a cut-out maze and square pattern as quickly and accurately as possible with their eyes closed. A first group of 16 subjects performed the task with their dominant right hand in a clockwise direction; a second group used their non-dominant left hand and traced the designs in a counter-clockwise direction. Activation was measured by comparing a condition where subjects held the pen in their hand without moving it (REST) to several maze tracing conditions: 1) during initial unpracticed performance (NAIVE), 2) after 10 min of practice on the same maze (PRAC) and 3) following practice with the task, but tracing a novel maze (NOVEL). To distinguish practice related from motor performance changes (e.g. changes in movement velocity) subjects were scanned while tracing an overleamed square design at high (SQ. FAST) as well as at low speed (SQ. SLOW). These conditions were also compared to REST. Results. Three types of effects were found 1. Movement related effects (increases in activity across conditions which shifted lateralization with the hand used) in the contralateral primary motor area and ipsilateral anterior, medial cerebellum. Localizations for the other two effects were the same for right and left hand performance. 2. Practice related effects (higher activations during NAIVE and NOVEL conditions than in PRAC, SQ.FAST and SQ. SLOW) in right pailetal and premotor cortex and left cerebellum, and 3. Capacity related effects (higher activation during NAIVE, NOVEL, PRAC, and SQ.FAST than SQ. SLOW) in left premotor and right cerebellar areas. As can be seen in Fig. 1, the cortical and cerebellar localizations of the effects are consistently contralateral. Z = 5 6 Z = -12 ~Movementrel~ed effe~ O Pra~ice rel~ed effe~ ~ ~ , CapaciW related effect Right Hand A performance [] Left Hand performance Z = -32 Figure 1. Primary motor, premotor, parietal and cerebellar activations displayed in Talairach '88 space. Conclusion. The consistency of the activation pattems and effects between specific cortical regions and contralateral cerebellar regions have implications on at least two levels. The results suggest physiological and probably anatomical relationships between specific cortical and cerebellar regions. Furthermore, the specific task related effects implicate separate functional relationships between premotor and cerebellum depending on their lateralization.

The locus of age-related movement slowing: sensory processing in continuous goal-directed aiming.

Prolonged movement times in elderly persons have been well documented; however, the locus of this slowing is uncertain. Kinematic analysis of discrete aiming has revealed deficits primarily in the target approach phase, suggesting inefficient feedback processing. This study investigated age-related movement slowing in a continuous aiming task, for which movements are mediated by feedforward and on-line sensory processes. Two-dimensional video-recordings were made of young and elderly adults performing reciprocal tapping using the right and left hands under three different accuracy conditions. The elderly subjects exhibited more discrete adjustments in the trajectories coupled with longer times in this period. Further, the elderly spent more time reversing direction between target hits, especially in the high accuracy condition. Longer time on target was seen in the left-hand performance of the elderly. Results suggest that the locus of age-related slowing in the performance of continuous aiming may reflect a greater dependence on slower feedback processes instead of rapid, on-line, and feedforward sensory processes. Age-related differences in hand performance may provide further insight into central processing deficits.

Key-finding, Fingering, and Timing in Piano Performance of Children

This study was an investigation of timing accuracy and tempo of performance in entry-level piano performance of children. Female and male subjects, 7, 9 and 11 years of age, using the right or left hand, performed three tasks. They performed the durational rhythm of a folksong by playing (1) with one finger on one key; (2) with one finger on five keys; and (3) with five fingers on five keys. Significant main effects for motor task, age, and gender were found for timing accuracy and tempo. Some significant interaction effects also resulted, especially for tempo. In general, performance was more inaccurate and slower for more complex tasks, for younger subjects, and for male subjects. Left-handed performance of the most complex task was more inaccurate and slower. Implications for piano pedagogy and theory of motor learning were considered.

A method for quantitating motor deficits in a nonhuman primate following MPTP-induced hemiparkinsonism and Co-grafting

This report describes a nonhuman primate model of MPTP-induced hemiparkinsonism and the recovery of motor function following co-grafting of adrenal medullary tissue and peripheral nerve into the lesioned area of the brain. A rhesus monkey ( Macaca mulatta) trained to perform a complex, discrete-trial, operant task served as the subject. After behavioral performance on the task had stabilized and a high level of accuracy was maintained, 0.4 mg/kg MPTP was infused acutely via the left carotid artery to produce a marked impairment of movement of the right arm. Eighteen weeks later, medullary tissue from the left adrenal gland was grafted along with peripheral nerve into the left caudate nucleus. During the original baseline training condition, right- and left-hand performances were comparable on all dependent measures. However, right-hand performance was severely impaired following unilateral MPTP treatment, and left-hand performance was unaffected. Right-hand performance recovered only after adrenal medullary tissue was transplanted with peripheral nerve into the brain. Neuroanatomical analysis of brain tissue showed the anticipated neuronal loss in the left substantia nigra due to MPTP administration and evidence of adrenal medullary cell survival in the area of the co-graft. The data demonstrate that the rhesus monkey and the behavioral task developed during this study can be efficacious in characterizing the effects of MPTP on psychomotor function and in assessing the outcome of new strategies for treating Parkinson's disease.

A Simple Dual-Task Study of Laterality, Sex-Differences and Handedness

Nine-hundred and eight-one right-handed and 55 left-handed subjects were required to tap with a pen for 10 secs between targets 6 cm apart whilst either saying nothing, reciting a tongue-twister or saying la-la. The numbers of dots produced in 10 secs in each condition were analysed. The right-handed group demonstrated the usually found degradation in their right-hand performance whilst reciting the meaningful words, but showed a lesser effect when saying la-la. Their left-handed performance was essentially unaffected. Absolutely no evidence for the presence of a sex difference in lateralization of language was found. The much smaller sample of left-handed subjects presented a complex picture of no significant effects, whether they were the sole left-handers in their family, or had other left-handed close relations.

Effects of hand and spatial conditions on visual line bisection.

This study examined the effects of hand and spatial conditions on a visual line bisection task with normal right-handers and proposed a normal range of deviation for this task in middle and advanced age. Twenty-four normal dextrals in their fifties and sixties performed a visual line bisection task using either the left or right hand under three spatial conditions: at the midline and in the left and right hemispaces. Our results revealed that performance was significantly affected by the hand used but not spatial conditions: Left hand performance was significantly further leftward than right hand performance. There was no significant interaction between the hand and spatial conditions. The mean deviation of the right hand was 2.2% of the half line length to the right of the true center. The possibility of left unilateral spatial neglect should be considered if a patient bisects a line with a deviation greater than 10% of the half line length to the right.

Testosterone and Hand Performance in Right-Handed Young Adults

The relationship between serum testosterone level and hand performance was studied in right-handed young adults without familial sinistrality. Hand performance was measured by a dot-filling task, which was found to be associated with serum testosterone depending upon sex. In women, the right- and left-hand performance was found to be negatively linearly related to testosterone; there was no significant correlation between the right- minus left-hand performance and testosterone. In men, right- and left-hand performance were found to be directly and inversely related to testosterone, respectively. This pattern exhibited some variations depending on eye and foot preferences. The difference in performance between hands was found to be positively linearly related to serum testosterone levels in men.

Simple reaction time changes after anterior callosotomy

Seven patients treated with anterior callosotomy for drug-resistant atonic seizures were tested to evaluate their simple reaction times (SRTs) to lateralized flashes before surgery (time 0) and then 15 (time I) and 90–100 days (time II) after the operation. The SRTs obtained at the three checkpoints were compared by means of ANOVA for the main effects of time, hand, and visual hemifield, and for their interactions. The mean number of omissions was also analyzed. The results showed increased SRTs at the first check after surgery, with a greater increase for the left hand, followed by a decrease close to the presurgical values. No difference between crossed and uncrossed conditions were observed; no differences in the omission rate were seen at postoperative evaluations. Finally, the left-hand performance showed a trend toward longer SRTs than the right-hand performance at all observations. Our data suggest that SRTs are only transiently affected by anterior callosotomy and that the side effects of surgery are greater in the left hand.

Lateralised Dual-Task Performance: The Effect of Muscular-Repositioning

In two experiments subjects performed tapping tasks requiring different degree of muscular repositioning while concurrently performing a speech task. In all concurrent speech conditions right-hand performance was disrupted more than left-hand performance, but the degree of this differential disruption did not alter as a function of the muscular repositioning requirements of the dual-tasks. It was concluded that rapid muscular repositioning does not appear to be the source of lateralised interference effects observed in concurrent task studies. However, it may be argued that some minimum level of repositioning is required, particularly if the differential effect reflects a lateralisation of “kind” rather than of “degree”. This needs further research. One relevant factor proposed here which may alter the degree of lateralised effects is the degree of muscular effort required to perform each of the dual-tasks.

The effect of using the dominant or nondominant hand on performance of the Rivermead Perceptual Assessment Battery

The Rivermead Perceptual Assessment Battery (RPAB) claims to be a standardized and validated test of visual perception. However, the published evidence suggests that several areas have not been considered by the authors of the test. One of these is whether the dominant or nondominant hand is used, particularly for those aspects of the test which require either pencil skills or the fine manipulation of objects. The purpose of this study was to conduct subtests of the RPAB on a group drawn from a nonclinical population to determine whether or not there are differences in performance between the dominant and nondominant hand. The study involved 35 first year university students who were right-hand dominant for writing. Each subject completed the four subtests twice, once with the right hand and once with the left. Statistically significant differences were found between right and left hand performance in both the score achieved and the time taken for right left copying shapes (RLCS) and right left copying words (RLCW), tests 11 and 12, and for time alone in cancellation (CA), test 15. No significant differences were found in 3D copying (test 13). Test 12 is of particular concern, as 24 subjects failed this test when using their nondominant hand. These findings have implications for the interpretation of test results when the RPAB is administered to stroke patients who, due to the nature and site of their lesions, may be forced to use the nondominant hand.

Hemispace and information control by the two cerebral hemispheres: Which interaction?

Two experiments employing subjects with different experience in tactile discrimination (blind and seeing subjects) were carried out to investigate the effect of the space location of stimuli on the information processing activity of the two cerebral hemispheres. An angle discrimination task that yields a right hemisphere superiority was used. In Experiment 1, seeing subjects showed a general superiority of the left hand (right hemisphere) which was more pronounced in the left hemispace with respect to the central and the right hemispace performance. In Experiment 2, blind subjects showed a significant superiority of the left hand in the central and in the left hemispace and no difference between the two hands in the right hemispace. In both experiments hemispace differences were due only to the modification of the left hand (right hemisphere) performance. These results suggest that the hemispace control by the contralateral hemisphere interacts only with the activity of the hemisphere dominant in the information processing.

Lateralized dual-task performance: The effects of spatial and muscular repositioning

In three experiments subjects were required to perform different manual tapping tasks using either the left or right hand while concurrently performing a speech task. The major independent variables examined were muscular effort and the spatial and muscular repositioning components of the tapping tasks. In all speech conditions right hand performance was disrupted more than left hand performance. The degree of this lateralized disruption did not alter as a function of variation in either muscular effort or the repositioning requirements of the manual task. However, muscular repositioning activity, unlike other components of the motor task, was affected bilaterally by the addition of the speech task. Overall the results suggest that the dual-task procedure can be used to assess two types of “lateralized” interference effects; one relating to right hand performance, the other to left hemisphere performance.

Manual Proficiency in Cattle's Intelligence Test in Left-Handed Male and Female Subjects

The relationship between nonverbal intelligence (spatial reasoning) and manual proficiency was studied in male and female left-handers. Manual proficiency was assessed by measuring the speed and accuracy in performing the dot-filling test. Nonverbal intelligence was assessed by Cattle's Culture Fair Intelligence Test. Females were found to be better than males in left-hand performance, and were more lateralized than males in manual proficiency. No significant sex difference could be established in right-hand performance. The right-hand skill was positively correlated to test intelligence (p less than 0.001). There was a negative correlation between the left- minus right-hand skill difference and the scores for nonverbal intelligence (p less than 0.001). The left-hand skill did not show any correlation with nonverbal IQ. It was concluded that the left-hemisphere is of utmost importance even for nonverbal intelligence; strong cerebral lateralization is disadvantageous for spatial reasoning.