Intermanual differences on neuropsychological motor tasks in a Japanese university student sample

We explored the intermanual difference scores of 128 Japanese university students for five typical neuropsychological motor tasks (grip strength, finger tapping, two versions of the grooved pegboard, and the dot‐filling test) and examined the relation between hand preference and intermanual difference in motor proficiency. Using the Edinburgh Handedness Inventory, 18 and 110 participants were identified as left‐ and right‐handed, respectively. Although the right hand performed better than the left for right‐handed participants, and vice versa, in all five tasks, the degree of intermanual difference varied between tasks. A discriminant function analysis using the laterality quotients of the five motor tasks as independent variables indicated that hand preference was predictable from the task performances with an accuracy of 90% or more. The dot‐filling test and finger tapping had stronger canonical loadings than the other tasks.     

Hemispheric alpha asymmetries and behavioral responses of aphasic and normal subjects for the recall and recognition of active, passive, and negative sentences

The hemispheric alpha asymmetries of a group of normal males, a group of normal females, and a group of aphasic patients (fluent and dysfluent) were examined with electroencephalographic (EEG) techniques under memory conditions of recall and recognition of active, passive, and negative sentences. Aphasic patients, regardless of classification, showed right hemispheric alpha suppression across memory conditions and sentence types. Both normal groups were found to have greater left hemispheric alpha suppression for the recall memory condition and greater right hemispheric alpha suppression for the recognition memory condition (males significantly more than females). The aphasic subjects performed better on recognition tasks compared to recalled tasks and active sentences compared to transformed sentences. Results are discussed as providing evidence of the aphasic subjects' greater dependency on information processing resources of the right hemisphere in the recovery of language function. The findings are also discussed as providing support for a multiple-resources model of information processing.     

Sex differences in cerebral laterality of language and visuospatial processing

Sex differences on language and visuospatial tasks are of great interest, with differences in hemispheric laterality hypothesized to exist between males and females. Some functional imaging studies examining sex differences have shown that males are more left lateralized on language tasks and females are more right lateralized on visuospatial tasks; however, findings are inconsistent. Here we used functional magnetic resonance imaging to study thirty participants, matched on task performance, during phonological and visuospatial tasks. For each task, region-of-interest analyses were used to test differences in cerebral laterality. Results indicate that lateralization differences exist, with males more left lateralized during the phonological task and showing greater bilateral activity during the visuospatial task, whereas females showed greater bilateral activity during the phonological task and were more right lateralized during the visuospatial task. Our data provide clear evidence for differences in laterality between males and females when processing language versus visuospatial information.     

Handedness and Reach-to-Place Kinematics in Adults: Left-Handers Are Not Reversed Right-Handers

The primary goal of this study was to examine the relations between limb control and handedness in adults. Participants were categorized as left or right handed for analyses using the Edinburgh Handedness Inventory. Three-dimensional recordings were made of each arm on two reach-to-place tasks: adults reached to a ball and placed it into the opening of a toy (fitting task), or reached to a Cheerio inside a cup, which they placed on a designated mark after each trial (cup task). We hypothesized that limb control and handedness were related, and we predicted that we would observe side differences favoring the dominant limb based on the dynamic dominance hypothesis of motor lateralization. Specifically, we predicted that the dominant limb would be straighter and smoother on both tasks compared with the nondominant limb (i.e., right arm in right-handers and left arm in left-handers). Our results only partially supported these predictions for right-handers, but not for left-handers. When differences between hands were observed, the right hand was favored regardless of handedness group. Our findings suggest that left-handers are not reversed right-handers when compared on interlimb kinematics for reach-to-place tasks, and reaffirm that task selection is critical when evaluating manual asymmetries.     

Gender, level of spatial ability, and lateralization of mental rotation

The present study indicates that some of the inconsistencies in studies of the lateralization of mental rotation may be a consequence of uncontrolled individual differences in the general level of spatial ability. In order to investigate the relation between spatial ability and the lateralization of mental rotation, 48 subjects (24 males and 24 females) were divided into three groups based on their performance on a standardized test of spatial ability. They then performed a lateralized two-dimensional mental rotation task. The results showed the typical mental rotation function in that angle of rotation and reaction time were linearly related. A significant spatial ability by visual field interaction indicated that subjects with low spatial ability had a left field advantage, whereas subjects with medium spatial ability showed no field advantage and subjects with high spatial ability showed a right field advantage. Gender also interacted with visual field, with males showing a left visual superiority and females an insignificant right visual field advantage. A significant three-way interaction of gender, spatial ability, and angle of rotation reflected the fact that low spatial males were more profoundly affected by rotation than the other groups. The results suggest that at least some of the inconsistent findings in studies of lateralization of mental rotation may be accounted for by differences in the level of spatial ability.     

Sex Differences in Visual Recognition Memory: Support for a Sex-Related Difference in Attention in Adults and Children

The selectivity hypothesis of Meyers-Levy (1989) proposes that cognitive sex differences reflect underlying differences in information processing between males and females. Males are considered to be more likely to organize information in a self-related manner, whereas females are more likely to adopt a comprehensive approach to information processing. We tested this hypothesis in children (10–15 years) and adults using recognition memory tasks. Tests were devised which employed male-oriented objects, female oriented objects, or random objects. In both the child and adult samples, females performed significantly better than males on tests using random and female-oriented objects. Males performed at the level of females only when tested for recognition of male-oriented objects. These results demonstrate that this sex difference is present prior to puberty and support the concept of sex differences in information processing.     

Sex task and processing strategy effects in hemispheric alpha asymmetries for the recall and recognition of arousal words: results from perceptual and motor tasks in males and females

Hemispheric alpha asymmetries of males and females were observed during perceptual and motor tasks requiring recall and recognition of words controlled for level of arousal (positive, negative, and neutral). Verbal reports of individual processing strategy were collected and analyzed relative to hemispheric alpha ratios. Results showed greater alpha suppression in the left relative to right hemisphere for recall as compared to recognition tasks and for word presentation when contrasted with motor conditions. High positive correlations were found between narrative report of processing strategy and hemispheric alpha data. A separate analysis revealed that seven subjects identified as highly analytic processors showed greater alpha suppression in the left relative to right hemisphere across tasks, conditions, and stimuli than did seven highly visual processors who, in contrast, demonstrated greater right hemispheric alpha suppression. Task difficulty and individual differences in processing style that modify cerebral laterality effects are discussed.     

Affecting Factors in Second Language Learning

The present study investigated the influence of sex, handedness, level in second langua ge (L2) and Faculty choice on the performance of phonological, syntactical and semantic tasks in L2. Level in L2 and sex were the most affecting factors. Subjects who achieved higher scores on L2 tasks had strong second language aptitude skills since they were those who had obtained a professional degree in the second language. Females performed better than males in syntax and semantics which is explained by the general female superiority on verbal tasks based on differences in hemispheric specialization for language functions between the sexes. Handedness and Faculty choice on the part of the participants had an impact on our results but only when combined with other factors.     

Differential construct validity of intelligence as popularly measured: Correlations of age with raw scores on the WISC-R for Blacks Whites, males, and females

Raw scores on the 12 WISC-R subtests and the verbal, performance, and full scale IQ scales were correlated with age in years separately for 938 White males, 137 Black males, 927 White females, and 153 Black females. Highest and lowest correlations from the four groups were then contrasted for each of the 15 WISC-R variables to determine whether the magnitude of the relationship between age and performance on current tests of intelligence is constant across race and sex. Regression coefficients between age and raw scores were also contrasted across groups. None of the 15 comparisons of corrections yielded differences that were statistically significant. Regression coefficients differed only with respect to the Full Scale IQ, showing smaller incremental changes with age for Black males than for other groups. The results indicated that the relationship between age and intelligence test performance is relatively constant across race and sex and supports the construct validity of the WISC-R as a measure of children's intelligence for Blacks, Whites, males, and females, though some evidence was found to indicate slower development of “g” in Black males as compared to the other groups.     

Bimanual handedness in adults who stutter

25 adult stutterers and 29 nonstutterers who were right-handed as defined by a positive Laterality Quotient on the Edinburgh Handedness Inventory were compared with respect to their pattern of hand use in performing seven common tasks that involve bimanual cooperation. Among the stutterers was a higher proportion of participants who showed anomalies in how they carried out the two tasks that required synchronous manipulation by the two hands. On two other tasks that required speeded performance, the groups were similar in dealing playing cards with the right or left hands, but the stutterers were slower than nonstutterers and did not show a right-hand advantage on a task requiring removal of a nut from a bolt. The results were interpreted as indicating difficulty by stutterers in carrying out synchronously different response elements of motoric tasks.     

Unilateral nostril breathing influences lateralized cognitive performance

Relative nostril efficiency (nasal cycle) is related to hemispheric EEG differences and performance on cognitive tasks. We investigated how unilateral forced nostril breathing influences spatial and verbal performance. Right-handed males and females performed both tasks under either left-nostril, right-nostril, or free-breathing conditions. Unilateral breathing affects performance differently in males and females. It influences male performance ipsilaterally on both tasks: Their spatial performance is better during right-nostril breathing, and their verbal performance is better during left-nostril breathing. Unilateral breathing influences female performance contralaterally, but only on the spatial task: Their spatial performance is better during left-nostril breathing. These differences within and between sexes may exist because unilateral nostril breathing differentially activates the two hemispheres and thereby facilitates performance, or because attempts of the brain to control the nasal cycle unilaterally interfere with performance.     

Gender differences in cognitive development

The potential effect of gender on intellectual abilities remains controversial. The purpose of this research was to analyze gender differences in cognitive test performance among children from continuous age groups. For this purpose, the normative data from 7 domains of the newly developed neuropsychological test battery, the Evaluación Neuropsicológica Infantil [Child Neuropsychological Assessment] (Matute, Rosselli, Ardila, & Ostrosky-Solis, 2007), were analyzed. The sample included 788 monolingual children (350 boys, 438 girls) ages 5 to 16 years from Mexico and Colombia. Gender differences were observed in oral language (language expression and language comprehension), spatial abilities (recognition of pictures seen from different angles), and visual (Object Integration Test) and tactile perceptual tasks, with boys outperforming girls in most cases, except for the tactile tasks. Gender accounted for only a very small percentage of the variance (1%-3%). Gender x Age interactions were observed for the tactile tasks only. It was concluded that gender differences during cognitive development are minimal, appear in only a small number of tests, and account for only a low percentage of the score variance.     

Cross-modal correlation of auditory and visual language laterality tasks: a serendipitous finding

Two experiments were conducted to investigate whether auditory and visual language laterality tasks test the same brain processes for verbal functions. In the first experiment, 48 undergraduate students (24 males, 24 females) completed both an auditory monitoring task and a visual monitoring task, with the Waterloo Handedness Questionnaire administered between the two tasks. The visual task was an analogue of the dichotic listening task used. It was hypothesized that a significant cross-modal correlation would be found, indicating that the dichotic listening task and the visual analogue task do, in fact, test the same brain processes for verbal functions. Results revealed a right ear advantage in the auditory task, a left visual field advantage (LVFA) in the visual task, and a cross-modal correlation of asymmetries of -.09. The LVFA observed in the visual task was replicated in Experiment 2, thus establishing its legitimacy. Results are discussed in relation with the type of processing that might produce such an unexpected finding on the visual task.     

Analyses of feeding lateralization in the small-eared bushbaby (Otolemur garnettii): a comparison with the ring-tailed lemur (Lemur catta)

Feeding related lateralization was examined in a population of 23 small-eared bushbabies (Otolemur garnettii). The three measures used to determine lateralization were food reaching, holding, and manipulation. Sex and age differences were found, with adult females showing a strong right bias and adult males a left bias. Juvenile males were weakly lateralized and less consistent across measures than adult animals. The use of standard scores to assess lateralization allowed species comparisons to be made. The results of this study were compared with results from a previous study on lateralization in the ring-tailed lemur (Lemur catta). Species comparisons found sex differences to be a stronger factor in lateralization than species differences.     

Visuospatial competency, handedness, and cerebral dominance

The present study addressed the question of Levy's (1974, Psychobiological implications of bilateral assymetry. In S. Dimond &; J. G. Beaumont, Hemispheric function in the human brain, NY: Halstead. Pp. 121–183.) proposal that left handers would have lowered spatial skills relative to verbal skills. In the first part of the study, performance on the PMA (visuospatial subtest) and WAIS Block Design subtest were compared between right and left handed high school and college samples. No support could be found for deficient visuo-spatial performance in the left handers. In the second part of the experiment, no relative impairment of visuospatial skills was found when subjects were classified into predicted speech dominance groups on the basis of a dichotic listening task and/or a visual half-field task. An extreme groups comparison of the most left dominant and most right dominant groups again yielded no significant differences in visuo-spatial performance. Finally, the relationship between degree of speech lateralization and visuo-spatial skills was examined. Only partial support for differences in cerebral organization for speech in left handers was found in the college sample.     

A performance measure of the degree of hand preference

The present paper describes a performance method for determining hand preference. The task requires participants to reach into different regions of hemispace to perform various actions (point, pick up, toss, sweep, and position) with a dowel located at each position. In accordance with the participants' hand preference as measured by the Waterloo Handedness Questionnaire, the preferred hand was used more frequently on the various performance tasks. The distribution of hand use in working space indicates that preferred hand use was almost exclusive for actions carried out in ipsilateral hemispace, while it is used only moderately for actions in contralateral hemispace, revealing that this hand is used throughout a wider range of extrapersonal space than the nonpreferred hand. These trends were observed across all of the performance tasks, suggesting that task complexity did not affect the frequency of preferred hand use either overall or, more specifically, in right hemispace, as was predicted. This finding is inconsistent with empirical work on questionnaires indicating that verbal reports of preferred hand use increase for more complex tasks (e.g., Steenhuis & Bryden, 1988). As well, performance on the preferential reaching task correlated significantly with hand preference as measured on the Waterloo Handedness Questionnaire (Bryden, 1977), unlike the other performance measure examined, indicating that the preferential reaching task is sensitive to differences in the degree of hand preference.     

Sex differences and bilateral electrodermal activity

The present study was aimed at replicating the results of a previous work on sex differences and electrodermal asymmetry from our laboratory (Román,et al. 1987). Skin conductance was bilaterally recorded in a sample of 44 dextral volunteers (22 males and 22 females) during a stimulus-free period, and the performance of two tasks (verbal and spatial). Subjects were grouped into two groups of right-hand and left-hand dominance in their electrodermal responses (EDRs) in accordance with their laterality coefficient scores at rest. During the tasks subjects appeareed clearly differentiated by their lateralization in the magnitude and frequency of EDRs independently of gender: right-hand responders showed higher electrodermal activity on their right hand, while left-hand responders showed higher electrodermal activity on their left hand. Sex differences were not observed within each responsiveness pattern. The orientation of phasic electrodermal changes remained constant throughout the different conditions.     

Right-left discrimination: effects of handedness and educational background

The present study investigated right left discrimination, with a paper-and-pen test with cartoon figures. The test consisted of line drawings of a person with no, one, or both arms crossing the vertical axis of the body in the figure. The subjects' task was to mark with a pencil, as fast as possible, which was the right or left hand in the figure. The line drawings were viewed from the back, from the front, or randomly alternating between the back and front views. Two studies were conducted. The first consisted of 393 adults: 153 males and 240 females; 338 right-handers and 55 left-handers. The results showed that the males performed better than the females. The left-handers and the right-handers performed equally well. However, the left-handed males performed better than the right-handed males. There was no difference in performance between the right-handed and the left-handed females. The second study consisted of 175 right-handed college students: 63 psychology students. 54 medical students, and 58 law students. The main finding was that the medical students performed better than the psychology students for all figure orientation subtests and for all arm positions. In comparison with the law students, the medical students performed at the same level on the back view subtest, but they performed better on the front view subtest and on two out of three arm positions on the alternating view subtest.     

Sex differences,activation level,and bilateral electrodermal activity

The effects of the activation level and subject’s sex on bilateral skin conductance measures were studied. Thirty right-handed subjects (15 males and 15 females) were exposed to three types of stimulus conditions: rest-period, verbal task and spatial task. Results showed that no relationship was observed between EDA asymmetry and the increase in the activation level induced by the verbal and the spatial tasks. Males showed both higher SCRs and greater frequency of responses on the left than on the right hand. The direction of electrodermal asymmetry remained constant regardless of the stimulus conditions. It was concluded that sex differences are important in the study of EDA asymmetry and that this asymmetry appeared to depend on peripheral variations.