Use Of Left Hand Research Articles

Manual laterality and strategy use for a coordinated bimanual task requiring precise and power grip in guenons and mangabeys

Bimanual tasks have been repeatedly shown to elicit manual asymmetries supposed to reflect hemispheric specialization. And yet, a coordinated bimanual task, the BOX task, appears to be inefficient in detecting biases of hand preferences. The BOX task involves two sequential actions requiring a precise grip, lift the lid of a box and grasp a small item inside the box (while holding the lid). In the present study, we compared manual laterality exhibited for the classic bimanual BOX task and for a unimanual BOX task in 11 De Brazza's monkeys (Cercopithecus neglectus) and 19 red-capped mangabeys (Cercocebus torquatus). In addition, we assessed strategy use for solving the bimanual BOX task. We found that left-hand use for grasping the item was higher in the BOX-bimanual task than in the BOX-unimanual task. We propose that this increase in left-hand use for grasping the item results from both a hemispheric specialization for lifting the lid and an advantage in using a skillful strategy. Indeed, we revealed (1) group-level right biases for lifting the lid and (2) a complete differentiation between the roles of the two hands in subjects showing a left-hand preference for grasping the item. Finally, the bimanual BOX task showed age differences in the two species, either in manual laterality for grasping the item or in strategy use. This study provides additional evidence that manual laterality might be sensitive to maturational factors and characteristics of the bimanual tasks such as the order and the features of sequential actions.

Laterality in the gestural communication of wild chimpanzees

We examined hand preference in the intentional gestural communication of wild chimpanzees in the Budongo forest, Uganda. Individuals showed some tendency to be lateralized, although less than has been reported for begging and pointing gestures in captivity; on average, their absolute bias was around 0.25 (where 1.0 represents complete right- or left-hand use and 0.0 represents no bias). Lateralization was incomplete even in individuals with major manual disabilities. Where individuals had a stronger preference, this was more often toward the right hand; moreover, as age increased, the direction (but not the extent) of hand preference shifted toward the right. While the gestural repertoire as a whole was largely employed ambilateraly, object-manipulation gestures showed a strong right-hand bias.

Which are the features of the TUBE task that make it so efficient in detecting manual asymmetries? An investigation in two Cercopithecine species (Cercopithecus neglectus and Cercocebus torquatus).

In the last decade, the TUBE task has been repeatedly shown to be highly efficient in detecting manual asymmetries that are strong hand preferences reflecting hemispheric specialization, in non human primates. The TUBE task was thus classified as a high-level task, presumably because it involves bimanual coordination. However, this task also requires a precise action made by digit(s), which may also be a crucial feature in eliciting manual asymmetries. In the present study, we compared hand preferences for a new TUBE-unimanual task and the classic TUBE-bimanual task, both performed mostly by using the forefinger, in 12 guenons (De Brazza's monkey: Cercopithecus neglectus) and 18 mangabeys (red-capped mangabey: Cercocebus torquatus). We found a relationship between hand preferences exhibited for the two tasks, suggesting that precise use of the forefinger may induce the activation of a specialized hemisphere in both the TUBE-unimanual and the TUBE-bimanual task. However, we showed that the strength of manual laterality was higher in the TUBE-bimanual task than in the TUBE-unimanual task, indicating that bimanual coordination may enhance the expression of hand preferences. We propose that the TUBE-bimanual task is highly efficient in detecting hemispheric specialization because bimanual role differentiation would make precise digit use highly skillful. Finally, we revealed species differences in hand use, especially in females: the most arboreal species, De Brazza's monkeys, increased left-hand use from the TUBE-unimanual to the TUBE-bimanual task whereas the most terrestrial species, red-capped mangabeys, increased right-hand use.

A Survey on the correlation between speech disorder and hemispheric lateralization

Background and Objective: Speech and language, particularly at school time are among children’s main and sensitive issues. Thus, speech disorders can affect all personality and psychological aspects of an individual and make him/her facing lots of problems. One of the factors which may be effective in the onset of this impairment is handedness. Because of receiving reactions from their parents and environment, left handed children have more readiness to suffer from speech disorders. Therefore, the present study was aimed at investigating speech disorders and the relationship between the disorder and handedness.Materials and Methods: The community under study included primary school children in Kermanshah (Iran) and 600 students were selected through two-stage cluster sampling method proportional to the volume from three different regions of education and training. The samples were evaluated through phonetics test and continuous speech research in terms of pathological symptoms and the existence of symptoms of disorder by a speech and language specialist; and for the child’s left handedness or right handedness, he was asked to write a simple sentence proportionate with his educational grade. Finally, the data were collected, pathological symptoms were recorded in the related checklist and speech disorder was diagnosed.Results: A total of 600 children were participated in the study of them 39.5% were boys (mean age 9.12 ± 1.52 (SD)). 49 students (8.2 percent) were left handed. The rate of speech disorder was obtained 11.2% (67 students) of which 6 students were left handed. Prevalence of speech disorder for boys and girls was 11% and 11.3%, respectively. Among the boys suffering the disorder, 7.7% was left handed, while this value for the girls was 9.8%. A significant correlation was not observed between the rate of disorder and gender and handedness (P < 0.05). Discussion: Although a significant statistical relation was not obtained between speech disorder and gender and handedness, the higher disorder prevalence among the female and left handed students can be attributed to the cultural context of male supremacy in Kermanshah and cultural and social pressures on women. These cases are considered as stress factors in increasing prevalence of the disorder. On the other side, the use of left hand is not so acceptable in various cultures; and in different societies, it may result in the child’s punishment. Furthermore, most of modern industrial tools have been mostly intended for the right handed; and these factors cause the left handed child to be under a constant pressure to change the handedness and the subsequent emotional excitements of speech disorders in him.

Hand use for grasping in a bimanual task: evidence for different roles?

It has been proposed that the two hands play different roles during bimanual object interaction. The right hand takes on an explorative, highly precise, manipulative role while the left hand supports and stabilizes the object. Does this division of labour influence hand use during visually guided grasping? Three experiments were designed to address this question: right-handed individuals put together 3D models using big or small building blocks scattered across a tabletop. Participants were free to build the models; however, it felt comfortable (Experiment 1) or they were required to build on a large (Experiment 2) or small (Experiment 3) base plate. In Experiment 1, the right hand was preferred for grasping while the left hand stabilized the building model. When participants used the large base plate (Experiment 2), right hand use for grasping decreased and left hand use increased. The plate provided freedom to the left hand from having to stabilize the building model, but it also interfered with right/left hand movements directed towards the opposite side of the grasping hand (contralateral movements). To investigate which of these two factors would explain the change in hand use for grasping, a very small base plate was used in the last experiment. Results showed similar right hand use values to those seen in the first experiment (without the use of a plate), even though the left hand was 'released from its stabilizing duties.' The results predict a left-hemisphere right hand advantage in the control of grasping.

Under what conditions will right-handers use their left hand? The effects of object orientation, object location, arm position, and task complexity in preferential reaching

When reaching to objects, it is known that the preferred hand is selected significantly more often for midline and ipsilateral reaches, although right-handers are more likely to continue to use their right hand to reach for an object in contralateral space (Mamolo, Roy, Rohr, & Bryden, 2006). The current study examined the influence of object orientation, object location, task complexity, and initial position of the hands on a reaching task in a sample of 45 right-handed adults. Participants reached to and picked up a mug oriented in one of three ways (handle to right, left, or neutral position) located in one of three spatial positions (left, right, and midline) from each of two starting hand positions: right hand over left, and vice versa. Along with the expected results, an interesting pattern emerged where both the orientation of the object and the position of the hands had significant effects on hand selection, such that the use of the non-preferred left hand was augmented in conditions where preferred-hand use was awkward and biomechanically inefficient. The results will be discussed in light of current theories accounting for hand selection preferences.

Interestingness measures for association rules: Combination between lattice and hash tables

There are many methods which have been developed for improving the time of mining frequent itemsets. However, the time for generating association rules were not put in deep research. In reality, if a database contains many frequent itemsets (from thousands up to millions), the time for generating association rules is more longer than the time for mining frequent itemsets. In this paper, we present a combination between lattice and hash tables for mining association rules with different interestingness measures. Our method includes two phases: (1) building frequent itemsets lattice and (2) generating interestingness association rules by combining between lattice and hash tables. To compute the measure value of a rule fast, we use the lattice to get the support of the left hand side and use hash tables to get the support of the right hand side. Experimental results show that the mining time of our method is more effective than the method that of directly mining from frequent itemsets uses hash tables only.

Comparison of the oral hygiene status and gingival health between left- and right-handed individuals

Objective: The efficient way to remove bacterial plaque from tooth surface depends on patient’s self care and motivation beside professional periodontal therapy. Brushing technique, duration, frequency, applied force and handicraft are known to be important in removing bacterial dental plaque. The effect of right and left hand usage is still a controversy subject. Our aim is to evaluate the oral hygiene status and gingival health between left- and right-handed individuals. Method: 116 patients who referred to University of Ondokuz Mayýs, Department of Periodontology participated the study. Groups were divided into patients using their right hands (Group 1) and patients using their left hands (Group 2). Total mean plaque (Silness-Loe) and gingival (Loe-Silness) indices (PI and GI, respectively), pocket depths (PD) as well as mean PI, GI and PD of right and left sides of maxilla and mandible, and gingival diseases were recorded. Chewing side preferences, smoking, brushing habits were also compared. Results: There was a significant difference between the total means of PI and GI values, and patients suffering from gingival diseases were found to be significantly higher in Group 1. There was no significance according to the means of PD, smoking, brushing frequency and the mean indices of left- and right sides of maxilla and mandible. PI and GI values were found to be significiantly higher in right-handed individuals in accordance with the previously published studies. Conclusion: Our results revealed that left-handed subjects proved to have better oral hygiene and PI and GI indices than the right-handed subjects. This better oral hygiene of the left-handed individuals is compatible with optimal gingival health and may be in relation with their undepressed neuromuscular abilities. Dentists may encourage their patients for using both hand usage during application of oral hygiene procedures and prevent the negative effects derived from only right or left hand use.

Three-Dimensional Movement Analysis of Handwriting in Subjects With Mild Hemiparesis

Harada T, Okajima Y, Takahashi H. Three-dimensional movement analysis of handwriting in subjects with mild hemiparesis. Objective To investigate the effects of hemiparesis on handwriting using a 3-dimensional movement analyzer. Design Comparative case study. Setting Ambulatory care clinic. Participants Right-handed patients (n=25; mean age ± SD, 62.3±10y) with mild right hemiparesis secondary to subcortical stroke, and age-matched (n=10; 65.6±13y) and age-unmatched (n=15; 32.4±10y) control subjects. Interventions Not applicable. Main Outcome Measures Time required to write a Japanese character of 2 different sizes and average speed of handwriting at the pen tip. Average radii of tracks of the moving pen tip, metacarpal head of the index finger, and distal end of the forearm during writing. Correlation coefficients of the instantaneous speed-time graph of the pen tip with that of the index finger and with that of the distal forearm during writing. Results Time for writing with the hemiparetic right hand was longer than that with the unaffected left hand ( P=.05∼.03), while it was shorter in healthy control subjects ( P=.07∼.05). In contrast with the left-hand writing, the track radius of the pen tip of the right-hand writing in patients with hemiparesis with normal joint position sense was significantly larger than that of the finger or distal forearm ( P=.01). The finding was the same as in the young and elderly control subjects. This right-left difference disappeared in the patients with hemiparesis with position sense impairment. The correlation coefficient of speed between the pen tip and the finger was larger in right-hand than left-hand writing in the control and sensory-normative patients with hemiparesis even though the difference was significant only in the healthy elderly subjects ( P=.03). Irrespective of the right or left hand use, the correlation coefficient between the pen tip and the finger or distal forearm significantly increased as the character size increased ( P=.03∼6×10 −6) in all subjects and patients. However, this size-related difference was less significant in the patients with sensory impairment. Conclusions The characteristics of handwriting movement by the dominant hand were preserved in patients with mild dominant-hand hemiparesis when joint position sense was normative but were lost in those with position sense impairment.

Laterality in semi‐free‐ranging black and white ruffed lemurs (Varecia variegata variegata): head‐tilt correlates with hand use during feeding

Previous studies in human and chimpanzee infants have identified a predictive relationship between early rightward head orientation and later right hand use. Data from lemurs suggest a leftward bias in hand preference, but there are no data on head positioning. The purpose of this study was to examine the relationship between head and hand preferences in the black and white ruffed lemur (Varecia variegata variegata). Ruffed lemurs rotate the head vertically during chewing in a behavior called head-tilting. Frequency of head-tilting and bouts of unimanual hand use were measured during normal feeding in a semi-free-ranging population of lemurs. Subjects were provisioned at feeding platforms twice daily with fresh fruits, vegetables, and other food items. Sampling was spontaneous and all observations were videotaped. No group-level bias was found for head-tilting, but a left hand bias emerged for hand use. A positive relationship was found between direction of head-tilting preference and direction of hand use preference such that left head-tilts increased as left hand use increased. Furthermore, left head-tilts increased as the degree of hand preference lateralization increased. When the hand used to bring food to the mouth just before head-tilting was examined, there was a strong bias for the left hand to precede left head-tilts. For right head-tilts, however, lemurs were equally likely to use either hand before head-tilting. Overall a strong relationship was found between the left hand and left head-tilting in black and white ruffed lemurs, suggesting a common link between these behaviors. However, the direction of bias was different from that seen in human and chimpanzee studies. Additional studies on patterns of laterality would be informative for understanding how laterality has changed across the primate order and the adaptive significance of laterality in primates.

A Dynamic Model for Limb Selection

Two experiments and a model on limb selection are reported. In Experiment 1 left-handed and right-handed participants (N = 36) repeatedly used one hand for grasping a small cube. After a clear switch in the cube’s location, perseverative limb selection was revealed in both handedness groups. In Experiment 2 the cubes were presented in a clockwise and counter-clockwise sequence to right-handed participant (N = 15). A spatial delay in the switch point between right-hand use and left-hand use was observed. The model simulates the experiments, by implementing the multiple-timescale dynamics of the action-selection process underlying limb selection. It integrates two mechanisms that were earlier proposed to underlie this selection aspect of manual activity: limb dominance and attentional information. Finally, the model is used to simulate Gabbard et al.’s (1997) experiment, offering a concise coupling of strength and direction of handedness.

Creativity and Psychopathology

Creative people have been found to score higher on psychopathologic scales in standardized tests, particularly on the scales that measure traits of psychoticism, and to be more likely to report an excess of nonright handedness compared with controls. However, results are inconsistent across surveys and methodologies, and the contribution of substance abuse has rarely been measured. In this study, 80 creative artists were compared with 80 matched noncreative controls on the Annett Hand Preference Questionnaire (HPQ), the Peters et al. Delusions Inventory, and the General Health Questionnaire. Creative artists were statistically more likely to admit the use of the left hand on the HPQ, with more widespread left hand use reported by artists involved in the creative activities traditionally associated with the right hemisphere (music and painting). They also scored higher on the Peters et al. Delusions Inventory independently from the level of psychopathology (measured with the General Health Questionnaire), from their laterality score (measured with the HPQ), and from their higher use of both licit and illicit drugs.

A cross-cultural comparison of pressures to switch left-hand writing: Brazil versus Canada

Attempts to switch left-hand preferences towards the right side are socialisation practices found in many countries (Perelle & Ehrman, 1994). Although researchers acknowledge that pressures against left-hand use contribute to the cross-cultural fluctuations in the prevalence of left- versus right-hand preference, there has been little systematic cross-cultural study of how these pressures are applied, and who are the major agents applying the pressures to change. Our study explored specific rightward conversion practices and the results of these practices among individuals from two countries. One sample of participants was from a culture categorised as formal, Brazil, and the second sample was from Canada, a nonformal culture (Hofstede, 2001). Researchers have argued that prevalence rates of right-handedness should be higher in cultures that value conformity, called formal cultures, and lower among members of nonformal cultures where conformity pressures are lax (Medland, Perelle, De Monte, & Ehrman, 2004). The socialisation practices used to foster a change from the left to the right side are also predicted to differ in frequency and in kind in formal versus nonformal cultural settings. These cultural differences are assumed to result in differences in success rates of the conversion attempts, with formal cultures producing higher numbers of successfully converted right-handers. Our findings indicate that the formal versus nonformal cultural explanation for cross-cultural fluctuations in the prevalence of hand preference types does not account for the characteristics of the rightward conversion experiences reported by participants in the two groups. We propose that hypotheses concerning the effects of cultural differences on hand preference formation be expanded to include possible biological or genetic variance between groups.

Hemispheric Functioning in Children With Subtypes of Attention-Deficit/Hyperactivity Disorder

Objective: The authors investigated line bisection performance in children with Attention-Deficit/Hyperactivity Disorder (AD/HD) subtypes. Previous research with neurotypical children found a rightward bias with right-hand use and a leftward bias with left-hand use; however, research with AD/HD participants has failed to similarly measure the effects of hand use, which was the focus of this study. Method: Line bisection was used to measure differences in right hemisphere functioning in children (7 to 12 years) with AD/HD-I and AD/HD-C. Results: Initial AD/HD group findings (without subtype differentiation) replicated previous research. However, further subtype analyses showed that the ADHD-I and ADHD-C groups perform significantly differently. Specifically, the ADHD-I group showed a leftward bias, irrespective of hand use, and the ADHD-C group showed a rightward bias, irrespective of hand use. Conclusion: These findings suggest that the subtypes represent two distinct disorders and that, unlike ADHD-C, ADHD-I may not be the result of right hemisphere dysfunction.

Cultural and environmental pressure against left-hand preference in urban and semi-urban Malawi

The study assessed views of teachers, pupils and their guardians on left-hand preference. Seventy-five percent of the responders indicated that the left hand should not be preferred for habitual activities and 87.6% of them indicated that left-handers should be forced to change the hand. Gender had significant effect on the view on left hand preference ( df = 1, OR (odds ratio) = 0.465, p = 0.027). Giving a handshake when greeting a person, drawing and writing were the three top target activities against left-hand preference. An assumption that the left hand is less skilled and less powerful than the right one was the most common reason for negative view on left-hand use. Most of volunteers reported that parents and close relatives were the primary group of people who usually discourage left-hand use. Eighty point one percent of the responders indicated that people should stop preferring the left hand as soon as somebody noticed their left-handedness. The results indicated that cultural and environmental pressures might significantly affect visibility of left-handedness in urban Malawian populations.

Asymmetries in postural control and locomotion in chimpanzees (Pan troglodytes)

Posture and locomotion are two of the most primitive and basic motor manifestations of an organism's behavior. Although the restrictions they impose on other motor functions are evident, few studies have considered the possibility of asymmetries in these behaviors in human and nonhuman primates, and how they might impact other asymmetries at higher functional levels. The aim of the current study was to explore in a group of 10 chimpanzees at the Madrid Zoo-Aquarium the degree of asymmetry in four behaviors related to locomotion (walking, ascending, descending, and brachiating) and four behaviors associated with posture (sitting, lying, hanging, and changing postures). Few subjects showed individual preferences, but significant trends in the group for some of the behaviors were found, including right-hand use when initiating quadruped walking, and left-hand use when descending and hanging. Some significant correlations also emerged: a negative one between walking and descending, and a positive one between walking and brachiating and between sitting and changing postures. No correlations were found between locomotor and postural modes. Although we cannot make generalizations on the population level at this time, these findings highlight the importance of considering postural and locomotion factors when studying motor asymmetries in primates.

Hand Preference in Attention Deficit Hyperactivity Disorder

In our Outpatient Department, we studied 56 subjects (41 males, 15 females; aged 5-16 yr.) with Attention Deficit Hyperactivity Disorder (ADHD) with respect to hand use in functional tasks via parental report. Left-hand use was markedly preferred, compared to that of a control group, more for complex than simple and for external (touching food and objects) than internal (scratching, rubbing eyes) tasks, suggesting a deficit in cerebral control of right-hand use. More patients were reported to have a left-hand preference than in the non-ADHD population. Furthermore, extent of laterality was greater for complex than simple external tasks and for external than for internal.

HAND PREFERENCE IN TURKISH POPULATION

The distribution of hand preference (self report) was studied in siblings and their parents originating from all parts of Turkey (N = 22,461). In total sample and siblings, there were significantly more right-handed women than men, and significantly more left-handed men than womenno significant sex difference for parents' handedness. The relative number for the right-handed parents significantly exceeded that for the right-handed siblings; the relative number for the left-handed siblings significantly exceeded that for the left-handed parents. It was concluded that there may be a sex difference in hand preference, but being only about 1% more left-handed men, and only about 1% more right-handed women; the right-handedness in new generation (siblings) is less than that in old generation (parents), due to freeing from cultural pressures against the left-hand use in everyday activities.

Repetitive Motion in Perception of Tactile Sensation in the Fingers of String Players

Little is known about the mechanisms that underlie the pathophysiology involved in the development of cumulative trauma disorders. Musicians, specifically string players, may be a useful model to examine the cumulative effects of repetitive motion given the highly attended movements of their left hands and the stereotypical grasp of their right hands. Musculoskeletal disorders related to playing are experienced by 39% to 87% of musicians, making musicians a potentially good model for the study of factors involved in development of cumulative trauma disorders. Sensory thresholds for two-point discrimination and light touch were measured in all phalanges of each digit, of each hand. Comparisons were made within and between a control group of 10 nonmusicians who did not engage in repetitive motion and 10 healthy musicians who did. There were 5 violinists, 2 violists, and 3 cellists. The Non-musician group perceived two-points and light touch at significantly lower thresholds in the proximal phalanges of the left hand than the right hand. Significant differences were not present between right and left hands for the means of distal, middle, and proximal phalanges of the Musician group. This lack of significant difference may be due to higher sensory thresholds associated with repetitive use of the left hand of the musicians.

Biobehavioural correlates of hand preference in free‐ranging female primates

In this research we examined biological and behavioural correlates of handedness in a subject cohort of 41 free‐ranging young female rhesus macaques (Macaca mulatta). Specifically, we examined relationships between handedness and cerebrospinal fluid (CSF) concentrations of the monoamine metabolites 5‐hydroxyindoleacetic acid (5‐HIAA) and homovanillic acid (HVA), plasma concentrations of the hormones cortisol and adrenocorticotropin (ACTH), prolactin, and multiple indices of social behaviour, including proximity to other animals, grooming, submission, and aggression. Handedness was determined through systematic observation of animals reaching for food in their unrestricted home environment. We found a population‐level bias for left‐hand use in this cohort of young females. The frequency of right versus left hand use was positively correlated with CSF 5‐HIAA, plasma cortisol concentrations, the frequency of submissive behaviour, and with the frequency of bouts in which animals received low‐level aggression. The positive correlation between right versus left hand use, submissive behaviour, and received aggression found here in females contrasts with the negative correlation among these same variables that we have previously reported in rhesus males. We conclude that these results may be explicable in terms of sex‐based differences in rhesus life‐history patterns, and that the influence of the serotonergic system on patterns of male aggression, social behaviour, and handedness, and the associations between handedness and social behaviour found previously among males may not be generalised to female rhesus macaques.