Hand preference and age in the United States.

A survey of 1,177,507 U.S. men and women between the ages of 10 and 86 included questions regarding hand preference for writing and throwing. Three effects were observed. Individuals with at least some left motoric bias comprised a smaller percent of the population with advancing age. This finding provides large-scale confirmation of a previously described phenomenon. Among sinistrals, concordance for writing and throwing was 2.2 times as prevalent as left-writing with right-throwing, and 4.1 times as prevalent as right-writing with left-throwing. These sinistral subpopulations displayed distinct and stable prevalence prior to age 50 and changing patterns of prevalence subsequent to age 50. The results confirm a decrease with age in the prevalence of sinistrality, but indicate that age-specific rates of mixed- and left-handedness are distinct. The implications for hypotheses regarding age-related change in the prevalence of sinistrality are discussed.     

Different pattern of hemisphere specialization between identical kinesthetic spatial and weight discrimination tasks

Thumb position discrimination and weight discrimination tasks were examined in female students. Task procedures were identical for the position and weight tasks. Different weights were loaded for each positioning and the thumb was abducted to discriminate the weight. The Weber ratio was obtained by the method of constant stimuli and was compared between right and left. The results of position discrimination indicated left thumb (right hemisphere) superiority, while the results of weight discrimination indicated no laterality despite identical tasks. Directed attention is suggested to play an important role in the appearance of hemisphere lateralization.     

Hand preference and accidents in India

The relationship between handedness and accidents in self-classified left- and right-handers in India was examined. It was hypothesised that the incidence of accidents would be greater in left-handers as compared to right-handers. Data were collected with the help of a questionnaire on side bias, along with a checklist on accidents. Analysis of data suggested that whether or not left-handers have more accidents than right-handers depends on the kind of activity examined: in India, left-handers have more driving accidents than right-handers, while right-handers have more sports accidents than left-handers.     

Hand preference and accidents in India

The relationship between handedness and accidents in self-classified left- and right-handers in India was examined. It was hypothesised that the incidence of accidents would be greater in left-handers as compared to right-handers. Data were collected with the help of a questionnaire on side bias, along with a checklist on accidents. Analysis of data suggested that whether or not left-handers have more accidents than right-handers depends on the kind of activity examined: in India, left-handers have more driving accidents than right-handers, while right-handers have more sports accidents than left-handers.     

Hand preference in homosexual men

The present study examined the distribution of hand preference and its relationship to immune system functioning and performance on neuropsychological tests in a sample of 993 homosexual men from the Multicenter AIDS Cohort Study comprising 502 HIV-1 seronegatives, 436 asymptomatic HIV-1 seropositives, and 55 men with diagnoses of AIDS or AIDS Related Complex. The prevalence of left-handedness in all of the groups (13.1-14.5%) was consistent with prior published reports of prevalent left-handedness in the general population. The distribution of hand preference scores (on a 5-item self-report questionnaire) was J-shaped and shifted to the right as in the general population. There were no differences between right- and left-handers in the immune system parameter of CD4 counts, nor was there any increase of self-reported allergies among the left-handers. We found a significantly larger number of 'outliers' on the neuropsychological measures for left-handers than for right-handers, both for HIV-1 seronegatives and seropositives. These results failed to replicate Lindesay's (1987) report of a leftward shift in manual preference among homosexual men, and failed to support Geschwind and Galaburda's (1985b) hypothesis of a link between homosexuality, handedness and autoimmune disorder. The differences between right- and left-handers on neuropsychological measures, independent of HIV-1 serostatus, are discussed in terms of Satz's (1972) model of pathological left-handedness.     

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 women--no 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.     

Hand preference in Italian students

Italian undergraduates (N = 2326) were administered the Italian revised version of Edinburgh Handedness Inventory (Salmaso & Longoni, 1985). Left-handedness was documented in relation to sex, university faculty, geographic origin and handedness pressure. A greater proportion (7.9%) of left-handedness was found compared to previous works on Italian samples. Additional results indicated a difference in left-handedness incidence among Southern, Central and Northern Italian regions. Results are discussed in terms of social and cultural influence.     

Hand preference by black-and-white snub-nosed monkeys (Rhinopithecus bieti) in captivity: Influence of tasks and sexes

Task complexity (Fagot & Vauclair 1991), bimanual complementary role differentiation (Uomini 2009), and the obligate use of a particular hemisphere (Rogers, 2009) have been proposed to explain why hand preferences in non-human primates are often influenced by tasks. We examined how tasks (reaching, carrying, extractive foraging, and object manipulation) and gender influenced hand preference in 11 adult black-and-white snub-nosed monkeys (Rhinopithecus bieti) out of a total of 13 known adult captive individuals of this species. A logistic regression was used to analyse 2556 bouts of binary left- vs right- hand use data. The explanatory variables are tasks, gender, and the interaction of tasks and gender. Hand preference is influenced by the task, in that subjects used the right hand significantly more often for extractive foraging and object manipulation than for reaching and carrying. We also found a significant interaction of sex and task: males used the left hand significantly more often than females for reaching and carrying, respectively, but not for extractive foraging or object manipulation. This is the first study on hand preference in R. bieti. As predicted, the hand preference in R. bieti is not a fixed property of the species or sexes but depends on the task.     

Hand preference by black-and-white snub-nosed monkeys (Rhinopithecus bieti) in captivity: influence of tasks and sexes

Task complexity (Fagot & Vauclair 1991), bimanual complementary role differentiation (Uomini 2009), and the obligate use of a particular hemisphere (Rogers, 2009) have been proposed to explain why hand preferences in non-human primates are often influenced by tasks. We examined how tasks (reaching, carrying, extractive foraging, and object manipulation) and gender influenced hand preference in 11 adult black-and-white snub-nosed monkeys (Rhinopithecus bieti) out of a total of 13 known adult captive individuals of this species. A logistic regression was used to analyse 2556 bouts of binary left- vs right-hand use data. The explanatory variables are tasks, gender, and the interaction of tasks and gender. Hand preference is influenced by the task, in that subjects used the right hand significantly more often for extractive foraging and object manipulation than for reaching and carrying. We also found a significant interaction of sex and task: males used the left hand significantly more often than females for reaching and carrying, respectively, but not for extractive foraging or object manipulation. This is the first study on hand preference in R. bieti. As predicted, the hand preference in R. bieti is not a fixed property of the species or sexes but depends on the task.     

Hand preference and the laterality of cerebral speech.

A theory of the origins of hand preferences (Annett, 1972) is outlined and its implications for the distribution of cerebral speech in handedness groups are examined. Five studies of dysphasia in right and left handers with unilateral cerebral lesions are compared and found surprisingly consistent. Data from three series found alike in all essential respects are combined to give a substantial number of cases with which to test the expectations of the theory. The agreement is close enough to justify a reconsideration of the model in the light of the evidence and also an analysis of possible reasons for the main differences between series. In spite of the many uncertainties involved in inferences from dysphasia to cerebral speech laterality, it is concluded that the evidence is strong enough to offer a useful test of hypotheses as to the distribution of cerebral speech in handedness groups. Other questions bearing on handedness and cerebral speech are briefly considered in order to show the explanatory range and power of the theory.     

Hand and foot preference in two cultures

ABSTRACT

Adult participants from India and France were requested to respond to hand and foot preference questionnaires. The items of the questionnaires assessed the choice of the preferred hand and foot on a scale that ranged from extreme left preference through no preference to extreme right preference. Results showed that both groups were more right lateralized for hand actions, whereas foot preferences were less right lateralized and spread across extreme right preference to no preference on the laterality index continuum for men and women. As compared to requiring large numbers for consistency in hand preferences across geographical regions, trends in the lateralization of hand and foot preferences may be consistently obtained with smaller samples. The study reveals the existing difference in lateral preferences between the upper and lower limbs that is sustained regardless of culture or geographical location and indicates the need for further investigation to know why the lower limbs are less lateralized than the upper limbs.     

Hand preference in a normal population

The Edinburgh Inventory was used to assess handedness in a normal population. The incidence of strong right-handedness increased with age and the incidence of left-handedness fell with age, both significantly. A non-significant increase in the incidence of left-handedness in twins was observed. The difference in the incidence of left-handedness for males and females failed to reach significance but more males were left-handed than females. Any difference in the incidence of left-handedness between the sexes must be small (less than 1.5%) and this has major theoretical implications.     

Enhanced spatial discrimination in paretic hands.

OBJECTIVE: Proper interaction between the sensory and motor system is essential for adequate control of voluntary movement. The influence of sensory alteration on motor activity is well known, while the effect of motor disturbance on sensory activity has yet to be clarified. We performed this study to investigate the influence of motor deactivation on sensory discrimination. METHODS: Using Johnson-Van Boven-Phillips domes, we evaluated tactile spatial discrimination (grating orientation threshold; GOT) in 62 patients with acute pure motor stroke and 75 age-matched healthy controls. RESULTS: In controls, the GOT was significantly lower in the dominant than in the non-dominant hands. The GOT was significantly reduced in patients' paretic hand, as compared to their unaffected hand and the hands of healthy controls in both the dominant and non-dominant side. The GOT of patients' paretic hand was significantly and inversely correlated to severity of their initial motor deficit in the non-dominant side (r=0.40, p<0.05), but not in the dominant side. CONCLUSIONS: These results suggest that motor deprivation enhances ascending sensory inputs. SIGNIFICANCE: This study provides additional information about the relationship between the motor and sensory system in humans.     

Hand preference in autistic children and their parents

Hand preference was tested in groups of between 40 and 50 autistic children and in sex-, age-, and ability-matched controls. Results were also compared with existing findings on normal children. Small differences occurred between the groups in the directions which would be predicted on the assumption that mental subnormality is associated with delayed development of normal patterns of handedness, and on the hypothesis that autistic children as a group will show a persistent slightly increased tendency to use the left hand. Parents of the autistic group were also assessed for handedness. Contrary to the prediction of slightly increased sinistrality in this group of subjects, some indication of increased dextrality occurred. Results were discussed in relation to possible genetic factors in the etiology of autism.The author thanks for their kind cooperation the staff and children at The Autistics Society School, Ealing; The Helen Allison School, Gravesend; St. Michael's School and The Ridgeway School, Warwick; St. Nicholas' School, Kenilworth; and the Brook School, Rugby; and also parents who took part.     

Hand and hemispace effects in tactual tasks in children

In Experiment I, 3-and 5-yr-old dextrals matched textures better by either hand when it operated in left hemispace. Girls and 3-yr olds were the more disadvantaged by non-alignment of hand and hemispace. In Experiment II, 8-yr-olds reproduced finger sequences; dextrals demonstrated a right-hand and sinistrals a right-hemispace superiority. In Experiment III, both a left-hand and a left-hemispace superiority appeared when 5-yr-old dextrals reproduced a static configuration of finger spacing. Asymmetries were generally stronger for the side of presentation than for the side of response. Our findings are consistent with the operation of two semi-independent systems, one involving hand-hemisphere connections, and the other mapping of extracorporeal space by the hemispheres.     

Event-related potentials elicited by visual stimulus-duration discrimination tasks.

Event-related potentials (ERPs) were recorded on subjects who discriminated the stimulus duration of two sequentially presented spots (S1 and S2). Four kinds of trials were included: short-duration match (S1 and S2 lasting 300 ms), short-duration conflict (S1 and S2 lasting 300 ms and 600 ms, respectively), long-duration match (S1 and S2 were 600 ms) and long-duration conflict (S1 and S2 were 600 ms and 900 ms, respectively). When S1 was equal to S2, components of P1, N1, P2, N2 and a delayed late positive component were recorded after the onset of S2. The other three negativities were elicited in both short and long duration conflict conditions. The three negative components peaked at 475, 600 and 900 ms in the short-duration condition, and they peaked at 805, 900 and 1200 ms in the long-duration condition. The first negativity was considered a visual mis-match negativity (vMMN), followed by a delayed N270 reflecting the conflict processing for duration in the brain. The last negativity, similar to N270, possibly reflects the second conflict processing activity evoked by stimulus offset.     

The scalp topography of potentials in auditory and visual discrimination tasks.

Averaged event-related cortical potentials (ERPs) were obtained from an array of scalp electrodes overlying the left hemicranium in response to regularly presented visual or auditory stimuli (non-signals)and to infrequent random replacements by different stimuli (signals) in the same modality. A motor response was required to the signals. Non-signal ERPs were subtracted from signal ERPs and the topographic distributions of the negative (N2 delta) and positive (P3 delta) components were plotted as isopotential maps. N2 delta distributions differed for the auditory and visual modalities, whereas P3delta was modality unspecific. These topographic data were compared to those from the previous study of missing stimulus potentials (Simson et al. 1976) using maps representing the contributions from unilateral cerebral sources. The N2 delta and negative missing stimulus potential distributions ascribed to cortical activity within the secondary auditory and visual regions, whereas the late positive component (positive missing stimulus potential or P3 delta) were considered to derive principally from inferior parietal association cortex.     

Hand preference, prematurity and developmental outcome at school age.

Information was obtained on the hand preference of 88 premature and 80 matched full-term children at 7-8 years old. These children were also evaluated for neurologic status, IQ, attention-deficit hyperactivity disorder, and learning disabilities. Although the difference on hand preference was not significant, 12% more of the premature children than the full-term children were left- or mixed-handed. Results showed that, among premature children, there is an association between non-right-handedness and cognitive and behavioral deficits and that left-handed children show relative clumsiness with the non-preferred hand.     

Tactile coactivation-induced changes in spatial discrimination performance.

We studied coactivation-based cortical plasticity at a psychophysical level in humans. For induction of plasticity, we used a protocol of simultaneous pairing of tactile stimulation to follow as closely as possible the idea of Hebbian learning. We reported previously that a few hours of tactile coactivation resulted in selective and reversible reorganization of receptive fields and cortical maps of the hindpaw representation of the somatosensory cortex of adult rats (Godde et al., 1996). In the present study, simultaneous spatial two-point discrimination was tested on the tip of the right index finger in human subjects as a marker of plastic changes. After 2 hr of coactivation we found a significant improvement in discrimination performance that was reversible within 8 hr. Reduction of the duration of the coactivation protocol revealed that 30 min was not sufficient to drive plastic changes. Repeated application of coactivation over 3 consecutive days resulted in a delayed recovery indicating stabilization of the improvement over time. Perceptual changes were highly selective because no transfer of improved performance to fingers that were not stimulated was found. The results demonstrate the potential role of sensory input statistics (i.e., their probability of occurrence and spatiotemporal relationships) in the induction of cortical plasticity without involving cognitive factors such as attention or reinforcement.     

ERPs and PET analysis of time perception: spatial and temporal brain mapping during visual discrimination tasks

ERPs were recorded from 12 subjects performing duration and intensity visual discrimination tasks which have been previously used in a PET study. PET data showed that the same network was activated in both tasks [P. Maquet et al., NeuroImage 3:119-126, 1996]. Different ERP waveforms were observed for the late latency components depending on the dimension of the stimulus to be processed: frontal negativity (CNV) for the duration task and parieto-occipital positivity (P300) for the intensity task. Using BESA software, the sources were first modelled with a "PET dipolar model" (right prefrontal, right parietal, anterior cingulate, left and right fusiforms). To obtain a better fit for ERPs recorded in each task, two sources (cuneus, left prefrontal area) had to be added. Consistently with PET findings, dipole modelling indicates that duration and intensity dimensions of a visual stimulus are processed in the same areas. However, ERPs also reveal prominent differences between the time course of the dipole activations for each task, particularly for sources contributing to the late latency ERP components. In the intensity task, dipoles located in the cuneus, the anterior cingulate, and the left prefrontal area yield largest activity within the P300 interval, then activity diminishes rapidly as the stimulus ends, whereas in the duration task, the cuneus and anterior cingulate are still active several hundred milliseconds following stimulus offset. Moreover, in the duration task, the activity of the right frontal dipole parallels the CNV waveform, whereas in the intensity task, this dipole is largely inactive. We assume that the right frontal area plays a specific role in the formation of temporal judgments.