SEARCH · PubMed Health

Results for “LEFT AND RIGHT-HANDEDNESS”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources

PubMed1986

Handedness patterns in autism suggest subtypes.

The present study reports preliminary data from two unselected samples of carefully diagnosed autistic subjects (children and adults) and an assessment procedure that includes a large sample of items, appropriate for lower-functioning autistic subjects, with multiple presentations within and between sessions 1 week apart. The study seeks to determine (1) whether a raised incidence of non-right-handedness exists in these samples (2) if so, what constructs best represent this shift in the handedness distribution (i.e., phenotype and CNS substrate) and (3) whether these handedness phenotypes are associated with different levels of cognitive functioning. The results reveal a dramatic shift away from right-handedness in both autistic samples, due to a raised incidence of two phenotypes, manifest left-handedness and ambiguous handedness. The ambiguously handed, who were postulated to represent substantial bilateral CNS pathology due to early brain injury, were found to have much lower intellectual scores in one of the study samples.

Adolescent↗

PubMed1992

Behavioral asymmetries of psychomotor performance in rhesus monkeys (Macaca mulatta): a dissociation between hand preference and skill.

Hand preferences were recorded for 35 rhesus monkeys (Macaca mulatta) as they manipulated a joystick in response to 2 computerized tasks. These preferences were then used to contrast 8 left- and 10 right-handed subjects on performance measures of hand skill. Individual hand preferences were found, but no significant population asymmetry was observed across the sample. However, the performance data reveal substantial benefits of right-handedness for joystick manipulation, as this group of monkeys mastered the 2 psychomotor tasks significantly faster than did their left-handed counterparts. The data support earlier reports of a right-hand advantage for joystick manipulation and also support the importance of distinguishing between hand preference and manual performance in research on functional asymmetries.

Animals↗

PubMed1990

Sex differences and handedness in hemispheric lateralization of tactile-spatial functions.

Sex differences in spatial processing and handedness were studied with a tactile-spatial task in 27 male and 29 female right-handed undergraduate students in psychology. Subjects were asked to identify amorphous shapes to investigate possible male right-hemisphere specialization for spatial functions and bilateral representation among the women. The Annett handedness questionnaire estimated extent of right-handedness. Subjects were classified by major, and women by phase of menstrual cycle. Analysis shows significantly more right-handedness in women and ambidexterity in men. Over-all, men do not perform significantly better than women, although men outperform women with their left hands when handedness is covaried. Within sex, no difference is seen between left and right hand scores for men, but women perform significantly better with right than left hands. Further analyses suggest men appear right-hemisphere dominant for this task whereas women show left-hemisphere dominance. Analyses of hormonal data support recent research, in that for women on the pill there is a trend to perform worse than all other groups. Engineering students perform significantly better than all other majors.

Adult↗

PubMed1977

Concerning the origin of handedness in humans.

The origin of right-handedness as the predominant chirality in humans seems to be related to the tendency of human (and presumably prehuman) mothers to hold infants on the left side. The latter practice has previously been ascribed to imprinting and the soothing sound of the mother's heartbeat on the infant. Given the practice of holding the child in this manner, dextral mothers will be more skillful at manipulation of objects and selectively favored.

Biological Evolution↗

PubMed1988

The distribution of hand preference in normal men and women.

The distributions of the hand preferences (Geschwind scores) were studied in men and women. The incidences of the right-, mixed-, and left-handers were 66.1, 30.5, and 3.4%, respectively. The left- and right-handers (LHs, RHs) were represented by two bars located at the opposite ends of a J-shaped histogram for the total sample, men, and women. The distributions for the total RHs, and male RHs were not J-shaped, but negatively skewed, the mode being close to the mean. The frequencies for the females increased linearly. The distributions for the LHs did not significantly deviate from normality. Except for the LHs, the percentage distributions of the Geschwind scores were J-shaped. The LHs were evenly distributed by chance to be expected in a random sample from a rectangular population. The incidence of weak right-handedness was significantly higher in men than women. The total RHs were more lateralized than the total LHs who showed a tendency toward weak left-handedness. In males, the incidence for weak left-handedness was significantly higher than that for strong left-handedness. The opposite was established for females. The probability of the consistent right-handedness was significantly higher in women than men. The LHs were less lateralized, and more widely dispersed than the RHs. The statistical analysis of the distributions indicated that females tended to be more lateralized, i.e., more right-handed, and more left-handed, than males.

Adult↗

PubMedDate not supplied

[Considerations on the cerebral organization of left-handed persons].

Left-handedness, being exception to the rule of right-handedness, has provoked several questions about its origins and the significance of its relationships with some individual traits, like cognitive style, personality, creativity, motor abilities. Investigations on left-handedness in recent years suggest that hand preference is linked to the peculiar functional organization of the two hemispheres of the brain.

Aphasia↗

PubMed1988

Regulation of Bacillus subtilis macrofiber twist development by D-cycloserine.

The effect of D-cycloserine on the establishment of twist states in Bacillus subtilis macrofibers was examined. Macrofibers produced in the presence of the drug differed in twist compared with those produced in its absence. The degree of twist alteration was dependent on the concentration of D-cycloserine in the growth medium. Macrofibers of different twist states representative of the entire twist spectrum from tight left-handedness to tight right-handedness were produced in strains FJ7 and C6D in four different ways: by control of the concentration of D-alanine, magnesium sulfate, or ammonium sulfate in the growth medium or by control of the growth temperature. The structures so produced were used to determine the effect of D-cycloserine on twist establishment starting from different twist states throughout the twist spectrum. In all but one case, twist resulting from growth in the presence of D-cycloserine was further towards the left-hand end of the twist spectrum than that produced in its absence, the exception being the unusual left-handed twist states produced in strains C6D and the closely related RHX 11S at high D-alanine concentrations described here. Studies of the interaction between D-cycloserine and D-alanine both used alone and used independently with the other twist-modifying systems (temperature, magnesium sulfate, and ammonium sulfate) revealed that changes in twist resulting from D-cycloserine were always in the opposite direction from those resulting from D-alanine. This antagonism suggests that the biochemical mechanism of twist regulation involves the metabolism of peptidoglycan, particularly reactions involving D-alanine or the dipeptide D-alanyl-D-alanine. This antagonism suggests that the biochemical mechanism of twist regulation involves the metabolism of peptidoglycan, particularly reactions involving D-alanine or the dipeptide D-alanyl-D-alanine. The possibility that peptidoglycan cross-linking is involved is discussed.

Alanine↗

PubMed1979

Schizophrenia: evidence of a subgroup with reversed cerebral asymmetry.

Normal right-handed individuals often show neuroanatomical asymmetries of the brain on computed tomography (CT), with wider right frontal and left occipital lobes. We examined the frequency of reversals of this normal asymmetry in a group of 57 right-handed, the schizophrenic patients. Compared to 80 normal right-handeders, the schizophrenics had an increased frequency of both frontal and occipital reversals. We then divided the patients on the basis of whether they had CT evidence suggestive of brain atrophy. Those without evidence of atropy had increased frontal and occipital reversals. Those with evidence of atrophy had no increase in reversals. This suggests that reversals of neuroanatomical asymmetry, and by implication abnormalities of lateralization, are relevant to a subgroup of schizophrenic patients with otherwise normal CT scans.

Adult↗

PubMed1980

Indonesian "Solo" (Ngandong) endocranial reconstructions: some preliminary observations and comparisons with Neandertal and Homo erectus groups.

Latex rubber brain endocasts of solo I, V, VI, X, and XI crania were prepared in order to determine accurate volumes by H2O-displacement and morphological description. The new volumes are not markedly different from previous estimates that had been done by mensuration formulae. The mean volume is 1,151 ml. The endocast surfaces, while devoid of gyral and sulcal relief patterns, do show a preponderance of left-occipital-right-frontal petalia patterns, suggesting right-handedness. Metrical observations support the viewpoint that the solo crania are more closely related to earlier Indonesia homo erectus than to Neandertals.

Animals↗

PubMed1981

Volumetric and asymmetry determinations on recent hominid endocasts: Spy I and II, Djebel Ihroud I, and the Sale Homo erectus specimens, with some notes on Neanderthal brain size.

Full brain endocast reconstructions of the Neanderthals, Spy I and II, Djebel Ihroud I, and the Homo erectus specimen from Sale, Morocco have yielded accurate volumes. Spy I = 1,305 ml; Spy II = 1,553 ml; Djebel ihroud I = 1,305 ml; Sale = 880 ml. While there are no remarkable gyral and sulcal patterns one can delineate, the brain endocasts do show evidence of left-occipital, right-frontal petalias, suggesting right-handedness, and possibly human cognitive specialization, involving symbol processing and visuospatial integration. Some speculations regarding Neanderthal brain size are also offered, in which it is suggested that their possibly larger brain sizes were related to greater muscularity than in modern Homo sapiens.

Animals↗

PubMed1984

Pathological left-handedness and ambiguous handedness: a new explanatory model.

A new model is presented which attempts to explain three pathological handedness phenotypes: pathological left-handedness (PLH), pathological right-handedness (PRH) and ambiguous handedness (AH). Revisions in the original model of PLH were prompted in order to account for reports of a raised incidence of both manifest left-handedness and AH in more severely retarded and/or brain-injured populations--namely, autistic. The new model generates specific predictions on the likelihood of different etiological subgroups within these disorders.

Autistic Disorder↗

PubMed1985

Infant rightward asymmetries predict right-handedness in childhood.

Eight children for whom measures of head preference and hand visualization had been determined in infancy were evaluated by parent questionnaire for hand preference at ages 3.5-6 yr. All six infants who maintained their heads to the right became right-handed as predicted, while neither infant with a non-right head orientation developed handedness in the predicted direction, though neither became right-handed. Similarly, the five infants who had visualized their right hands more frequently than the left became right-handed children as predicted; of the three infants who did not visualize the right hand more frequently, none developed handedness as predicted. None of the infant measures correlated with childhood handedness. These results suggest support for the genetically based right shift factor proposed by ANNETT (Behav. Genet. 8, 227-249, 1978).

Child↗

PubMed1986

The influence of gender, handedness and head-turn on auditory asymmetries.

Subjects performed dichotic tasks with their heads turned 90 degrees to the left, 90 degrees to the right, and straight ahead. In Experiment 1 the stimuli were digits and the subjects varied in both sex and handedness. Right-handedness males showed a significant right-ear advantage under the head-right and head-straight conditions, while left-handed males and both right- and left-handed females failed to show any consistent ear asymmetries. In Experiment 2 the stimuli were melodies and the subjects were all right-handed. Head-turn had no significant influence on the results, and only the males showed a significant left-ear advantage. Overall, the results confirm previous findings that sex and handedness may influence auditory asymmetries, but fail to reveal systematic effects of head turn.

Adolescent↗

PubMed1983

Comparison of patterns of handedness between twins and singletons in Japan.

The handedness questionnaire of thirteen items which was identical to that employed in our previous study on singletons was administered to 62 monozygotic (MZ) and 48 dizygotic (DZ) twin pairs in Japan. Information on forced conversion of hand usage in childhood was also obtained. Results indicated that the incidence of left-handedness was 3.6% and that of non-right-handedness (which includes mixed- and left-handedness) was 5.9%. There was no significant difference in the incidence of left-handedness or of non-right-handedness between MZ and DZ twin groups. The proportion of converted right-handedness in MZ twins was slightly higher than in DZ twins. MZ pairs were somewhat more concordant for handedness than DZ pairs. Item analysis indicated that the incidence of individuals who use the left hand for writing and eating was only 0.9% and 1.8%, respectively. A comparison of the results of the present survey on twins with those of our previous one on singletons revealed that the incidence of left-handedness or non-right-handedness in twins is the same as that in singletons. Twins (especially MZ twins) have experienced a forced conversion to right-hand usage more frequently than singletons.

Adolescent↗

PubMed1989

Handedness and anxiety in normal and clinical populations.

Previous research has yielded inconclusive evidence as to the relationship between handedness and anxiety. In order to further examine this relationship, two studies were carried out. In the first study, university students (N = 167) completed the Edinburgh Handedness Inventory, the Fear Questionnaire, and the Maudsley Obsessive Compulsive Inventory. No evidence was found to suggest that phobic fears are more prevalent or more severe among individuals with a tendency to left-handedness than among pure right-handers. Statistical tests reveled a marginally significant positive association between social phobia scores and right-handedness. In the second study, handedness was assessed in 77 anxiety disorder patients and compared with handedness patterns in normal controls. Again, no support was found for the claim that anxiety and left-handedness are related to each other. However, the normal pattern of women being more right-handed than men was reversed in the anxiety disorder group.

Adult↗

PubMed1975

Frequency of left-handedness among the Andhra Pradesh people.

The percentages of left-handed people among the males and females of Andhra Pradesh tribals in India were found to be 15.49 and 7.79, and in Hindus 6.9 and 4.65. The difference between the sexes among tribals is significant. The tribal people studied were Koya Doras, Sugalis (or Lambadis), and Konda Reddis. It is suggested that similar quantitative studies of left-handedness should be made in other tribal and aboriginal populations before they are culturally comditioned to right-handedness.

Ethnicity↗

PubMed1991

Sex, handedness, mathematical ability, and biological causation.

An important part of Benbow's (1988) assertion that sex differences in mathematical ability are primarily due to biological factors is the link between a trait that is assumed to reflect differences in brain organization (left-handedness) and mathematical giftedness. It is shown that the link between mathematical giftedness and an increased prevalence of left-handedness is not convincing. However, Benbow's (1986) data do show a convincing link between strong right-handedness and the lack of mathematical giftedness, in agreement with Annett and Manning's (1990a, 1990b) recent work.

Aptitude↗

PubMed1985

Hand preference in schizophrenics and handedness conversion in their childhood.

A handedness questionnaire which was given to 1774 schizophrenic inpatients was identical to that employed in our previous study on healthy students. Information was obtained on forced conversion of hand usage in childhood and the occurrence of left-handedness in their families. Family history of schizophrenia was also investigated. There were no significant differences in the prevalence of left-handedness or non-right-handedness (i.e., left-handedness and ambidexterity combined) between schizophrenic patients and normal subjects. However, the rate of converted right-handedness in schizophrenics was higher than that in normal people. The incidence of original non-right-handedness (i.e., present non-right-handedness and converted right-handedness combined) in schizophrenics was greater than that in normal controls.

Adolescent↗