Predicting spatial ability from hemispheric ‘non-verbal’ lateralisation: Sex,handedness and task differences implicate encoding strategy effects

Left- and right-handed males and females were given a divided visual field delayed form recognition task and three tests of visuospatial ability of varying degrees of complexity [(a) AH4 diagrammatic section, using 2-D items testing non-verbal reasoning; (b) Revised Minnesota Paper Form Board, using 2-D items testing simple spatial ability; (c) Differential Aptitude Test Space Relations, using 3-D items testing spatial manipulation]. Females of both handedness groups were left hemisphere dominant for the recognition task; males displayed no hemisphere difference. Only the most complex visuospatial test discriminated between groups, both left- right-handed males were superior to their female counterparts. There were no handedness effects for either laterality or spatial ability. Since it was also possible in some cases to predict spatial ability from laterality within sex/handedness groups, the findings were discussed in terms of the contribution of both structural and encoding factors to individual and group differences in laterality and cognitive abilities.     

Real-life spatial skills, handedness, and family history of handedness

According to , pronounced left hemisphere lateralization for language abilities in women, as in female absolute right-handers, limits their right hemisphere capacity and spatial abilities. This study examines the degree of handedness and the family history of non-right-handedness with respect to real-life spatial abilities in women. Twenty-four women had, first, to learn a new route and, second, to orient themselves within a labyrinth. In the former task, the number of errors and completion time were evaluated; in the latter task, degree of error for orienting was recorded. The results show that, contrary to Annett's prediction, right-handers with and without a family history of non-right-handedness did not differ on these measures. In addition, and unexpectedly, absolute right-handers were found to surpass non-absolute ones in the spatial orientation task. These findings do not support Annett's hypothesis and are discussed in relation to functional cerebral organization.     

Role of the left hemisphere in sign language comprehension

We investigated the relative role of the left versus right hemisphere in the comprehension of American Sign Language (ASL). Nineteen lifelong signers with unilateral brain lesions [11 left hemisphere damaged (LHD) and 8 right hemisphere damaged (RHD)] performed three tasks, an isolated single-sign comprehension task, a sentence-level comprehension task involving simple one-step commands, and a sentence-level comprehension task involving more complex multiclause/multistep commands. Eighteen of the participants were deaf, one RHD subject was hearing and bilingual (ASL and English). Performance was examined in relation to two factors: whether the lesion was in the right or left hemisphere and whether the temporal lobe was involved. The LHD group performed significantly worse than the RHD group on all three tasks, confirming left hemisphere dominance for sign language comprehension. The group with left temporal lobe involvement was significantly impaired on all tasks, whereas each of the other three groups performed at better than 95% correct on the single sign and simple sentence comprehension tasks, with performance falling off only on the complex sentence comprehension items. A comparison with previously published data suggests that the degree of difficulty exhibited by the deaf RHD group on the complex sentences is comparable to that observed in hearing RHD subjects. Based on these findings we hypothesize (i) that deaf and hearing individuals have a similar degree of lateralization of language comprehension processes and (ii) that language comprehension depends primarily on the integrity of the left temporal lobe.     

Right hemisphere participation in reading

This study examined whether the right hemisphere's contribution to lexical semantic processing is greatest when it is "disinhibited." Skilled reading may require the controlled modulation of interhemispheric interaction: the left hemisphere (or some other control mechanism) may regulate the subprocesses of reading by selectively "inhibiting" and "disinhibiting" right hemisphere function. Right-handed undergraduates concurrently performed two tasks: a lateralized semantic or rhyme task and a verbal memory task. It was hypothesized that right hemisphere reading processes would be disinhibited when the left hemisphere was "occupied" with the memory task. This hypothesis was supported for a subgroup of subjects who showed evidence of inhibition of right hemisphere function (i.e., left hemisphere dominance for lexical processing) when the lateralized semantic task was performed alone. Across subjects, there was a strong correlation between the degree of left hemisphere dominance in the single-task semantic conditions and the degree of disinhibition of right hemisphere function in the dual-task semantic condition.     

Clarification of the dual task dilemma: Lateralized effects for perfunctory and purposeful tasks in left- and right-handed males

The hypothesis that behavioral asymmetries with the dual task paradigm represent manual dominance was investigated with right- and left-handed males performing verbal and spatial tasks ordered by complexity. Lateralization was assessed for nonideational (perfunctory) and ideational (purposeful) components of tasks with multivariate and ANCOVA procedures. The outcomes of prerequisite tests showed the assumptions for conducting ANCOVA procedures were not satisfied with different handedness groups in the same design. However, results of the multivariate analyses suggest lateralized effects are more likely to represent the cognitive task when interference is high and may represent manual dominance when interference is low.     

Discourse deficits following right hemisphere damage in deaf signers

Previous findings have demonstrated that hemispheric organization in deaf users of American Sign Language (ASL) parallels that of the hearing population, with the left hemisphere showing dominance for grammatical linguistic functions and the right hemisphere showing specialization for non-linguistic spatial functions. The present study addresses two further questions: first, do extra-grammatical discourse functions in deaf signers show the same right-hemisphere dominance observed for discourse functions in hearing subjects; and second, do discourse functions in ASL that employ spatial relations depend upon more general intact spatial cognitive abilities? We report findings from two right-hemisphere damaged deaf signers, both of whom show disruption of discourse functions in absence of any disruption of grammatical functions. The exact nature of the disruption differs for the two subjects, however. Subject AR shows difficulty in maintaining topical coherence, while SJ shows difficulty in employing spatial discourse devices. Further, the two subjects are equally impaired on non-linguistic spatial tasks, indicating that spared spatial discourse functions can occur even when more general spatial cognition is disrupted. We conclude that, as in the hearing population, discourse functions involve the right hemisphere; that distinct discourse functions can be dissociated from one another in ASL; and that brain organization for linguistic spatial devices is driven by its functional role in language processing, rather than by its surface, spatial characteristics.     

A study of alpha hemispheric asymmetries for verbal and nonverbal stimuli in males and females

The alpha hemispheric asymmetries of males and females were examined with electroencephalographic (EEG) techniques during exposure to connected speech and nonlinguistic stimuli. The subject selection controlled for familial handedness and each subject was administered the Block Design and Vocabulary Subtests of the WAIS as a general measure of “visual-spatial” and “verbal” ability. The results showed that there was less alpha in the right hemisphere for nonverbal tasks and less alpha in the left hemisphere for verbal tasks. The females showed significantly more “lateralization” during the tasks as compared to the males. The results are discussed in terms of processing differences and the possible effects of subject variables, stimulus mode, stimulus presentation, and task requirements on neurolinguistic research results.     

The effects of voluntary lateral orienting on positive manifold for lateralized cognitive tasks

As an extension of previous studies (Urbanczyk, Angel, & Kennelly, Brain and Cognition, 8, 206-226) examining the effects of unimanual tapping on lateralized cognitive tasks, lateral body orienting was added to an established dual task paradigm to generate differential hemispheric activation and shifts of attention. One hundred twenty right-handed university students retained sequences of digits or spatial locations for 20 sec either alone or during finger tapping. By turning head and eyes left or right, the hemisphere congruent with the sequences (LH for digits, RH for locations) or incongruent (vice versa) was activated. Activation had little effect on retention means but greatly affected resource composition, supporting task performance. Congruent orientation produced significantly higher positive correlations between digit and location tasks than incongruent orientation. Females showed higher sequence retention correlations than males across both orienting groups. For females, congruent activation enhanced tapping rates and tapping-retention task correlations. For males, activation affected neither of these. These results suggest that congruent attentional orienting may couple or integrate regions of the less activated hemisphere into networks of the more activated hemisphere. Greater inter- and intrahemispheric connectivity in the female cortex may produce a greater dependence upon a general attentional "resource."     

The Relationship Between Nonclinical Schizotypy and Handedness on Divergent and Convergent Creative Problem-Solving Tasks

Previous research indicated a relationship between hemispherical dominance, the extent of schizotypal tendencies, and creativity. Little research has been conducted to assess the degree of schizotypy in nonclinical samples. The aim of this study was to determine the extent to which measures of multidimensional schizotypy and predominant handedness could predict measures of creativity, as assessed by both divergent and convergent tasks. One hundred and twenty-six participants participated in a quasi-experiment involving tests of predominant handedness, schizotypal tendencies, and divergent and convergent thinking. Results suggest that individuals who scored high on a test for schizotypal tendencies performed better on divergent problem-solving tasks, as opposed to low scoring individuals who performed better on convergent problem-solving tasks. Furthermore, results suggest that there was relationship between handedness on divergent and convergent thinking. There was, however, a relationship between handedness (right hemisphere) on the degree of schizotypal tendencies with left-handed individuals demonstrating greater schizotypal tendencies.     

工作记忆中汉字与空间的分离及动态优势半球的ERP效应

测量了14名正常被试完成延迟匹配任务时的事件相关脑电位(ERP)。在刺激消失后的延迟阶段,汉字任务和空间任务均在头皮中前部额区产生P260和晚期正成分(LPC), 在头皮后部顶枕区产生N150和晚期负成分(LNC)。汉字任务的P260表现出右脑优势, 400-800ms时LPC转变为与空间任务相比较的汉字左脑相对优势。空间任务的P260在左右脑无差异,400-800ms时LPC转变为右脑优势。头皮后部无显著差异。本研究提供了工作记忆中汉字与空间信息保持的分离及其优势脑动态变化的ERP证据。     

The influence of emotional faces on the spatial allocation of attention

Background objectives: Studies suggest that the right hemisphere is dominant for emotional facial recognition. In addition, whereas some studies suggest the right hemisphere mediates the processing of all emotions (dominance hypothesis), other studies suggest that the left hemisphere mediates positive emotions the right mediates negative emotions (valence hypothesis). Since each hemisphere primarily attends to contralateral space, the goals of this study was to learn if emotional faces would induce a leftward deviation of attention and if the valence of facial emotional stimuli can influence the normal viewer’s spatial direction of attention. Methods: Seventeen normal right handed participants were asked to bisect horizontal lines that had all combinations of sad, happy or neutral faces at ends of these lines. During this task the subjects were never requested to look at these faces and there were no task demands that depended on viewing these faces. Results: Presentation of emotional faces induced a greater leftward deviation compared to neutral faces, independent of where (spatial position) these faces were presented. However, faces portraying negative emotions tended to induce a greater leftward bias than positive emotions. Conclusions: Independent of location, the presence of emotional faces influenced the spatial allocation of attention, such that normal subjects shift the direction of their attention toward left hemispace and this attentional shift appears to be greater for negative (sad) than positive faces (happy).     

Left hemisphere language lateralization in bilinguals and monolinguals

Tachistoscopic studies of lateralization in bilinguals suggest that there is a greater degree of right hemisphere involvement in their processing of language than is typically found in monolinguals. However, most of the studies reviewed failed to control the sex, handedness, and degree of fluency of the subjects and did not include a monolingual comparison group. The present study used adult right-handed males (Portuguese-English bilinguals and English-speaking monolinguals) in a tachistoscopic word-reading task. In Experiment 1, the words from the bilinguals’ two languages were presented in mixed blocks, while in Experiment 2, they were presented in separate blocks. The results were: (1) a similar level of left hemisphere advantage for language in the bilingual and the monolingual groups, (2) no evidence of greater heterogeneity of asymmetry patterns in bilinguals, and (3) a significant correlation (r=.61) for lateralization levels of the bilinguals’ two languages. These results indicate that language is processed primarily in the left hemisphere of both bilinguals and monolinguals.     

Asymmetry of cognitive functioning as a possible predictor for vocational counseling and personnel classification

Neuropsychological research indicates the asymmetrical functioning of the cerebral hemispheres. The right hemisphere appears to specialize in global, synthetic, spatial, time-independent processing, whereas the left hemisphere is dominant in analytic, verbal, sequential, time-dependent processing. It is proposed here that in tasks, jobs, and occupations entailing hemisphere-specific abilities, personnel with superior functioning of the relevant hemisphere would perform more proficiently. A test battery designed to assess hemispheric dominance was administered to two groups, Economics and Arts students. Significant differences in mean performance were found between groups, as predicted. The findings suggest that the identification of individual patterns of hemispheric specialization may be useful for matching people's abilities with job demands.     

Cerebral laterality and depression: differences in perceptual asymmetry among diagnostic subtypes

Examined the influence of diagnostic subtype of depression on perceptual asymmetry for dichotic listening and visual tachistoscopic tasks. A total of 65 unmedicated patients with major depressive disorders and 30 normal controls were tested on a verbal and nonverbal task in each modality. Patients diagnosed according to the DSM-III with melancholia had abnormal perceptual asymmetry for dichotic nonsense syllable and complex tone tasks. In contrast, patients having a nonmelancholic "atypical depression" (reactivity of mood with preserved pleasure capacity and associated features) did not differ from normal controls on these tasks, but had an increased incidence of left handedness. Bipolar depression (history of hypomania) differed from unipolar depression in showing abnormal perceptual asymmetry for a tachistoscopic dot enumeration task. Alterations of perceptual asymmetry in melancholia and bipolar depression were consistent with hypothesized right hemisphere dysfunction.     

On the different roles of the cerebral hemispheres in mental imagery: the "o'Clock Test" in two clinical cases

This paper develops the hypothesis of different roles of the two hemispheres in imaginal processes. A test designated the "o'Clock Test" is proposed, which contains closely confrontable perceptual and imaginal tasks. It enables examination of the abilities both to generate mental images and to explore them in their right and left halves (R + L Condition). This test was used to examine two patients, one severely affected by hemi-inattention resulting from a right posterior lesion, and the other with a selective deficit of imagery due to a left occipital lesion. The former demonstrated left neglect in both perceptive and imaginal capacities, while the latter was able to perform correctly only the perceptive tasks. These results suggest that the right hemisphere has functions of organization and spatial exploration at both perceptive and imaginal levels, and that the left hemisphere's role is to generate mental images.     

Hemispheric specialization for categorical and coordinate spatial representations: A reappraisal

The purpose of the present study was to examine Kosslyn's (1987) claim that the left hemisphere (LH) is specialized for the computation of categorical spatial representations and that the right hemisphere (RH) is specialized for the computation of coordinate spatial representations. Categorical representations involve making judgements about the relative position of the components of a visual stimulus (e.g., whether one component is above/below another). Coordinate representations involve calibrating absolute distances between the components of a visual stimulus (e.g., whether one component is within 5 mm of another). Thirty-two male and 32 female undergraduates were administered two versions of a categorical or a coordinate task over three blocks of 36 trials. Within each block, items were presented to the right visual field-left hemisphere (RVF-LH), the left visual field-right hemisphere (LVF-RH), or a centralized position. Overall, results were more supportive of Kosslyn's assertions concerning the role played by the RH in the computation of spatial representations. Specifically, subjects displayed an LVF-RH advantage when performing both versions of the coordinate task. The LVF-RH advantage on the coordinate task, however, was confirmed to the first block of trials. Finally, it was found that males were more likely than females to display faster reaction times (RTs) on coordinate tasks, slower RTs on categorical tasks, and an LVF-RH advantage in computing coordinate tasks.     

Apraxia in a patient with atypical cerebral dominance

Liepmann postulated that the left hemisphere of right-handed persons contains the "movement formulas" that control purposeful skilled movements of the limbs on both sides of the body. Accordingly, in right-handers apraxia should follow damage to the left hemisphere, whereas right hemisphere damage should not lead to apraxia. Although this is generally true, we recently examined a right-handed man who after a right hemispheric stroke became aphasic and apraxic with his nonparalyzed right hand. Our observations suggest that the right hemisphere of this right-handed man made a critical contribution to the planning and execution of skilled movements. This case provides evidence that right-handers should not be considered a homogeneous group in terms of cerebral motor dominance and that contrary to Liepmann's postulate, hemispheric dominance for the control of skilled movements does not entirely determine handedness.     

Familial sinistrality, sex, and laterality differences in naming and Lexical Decision Latencies of right-handers

Sixty-four subjects, divided into four groups of 16 according to sex and familial sinistrality (FS), were given a lateralized Object-Naming Latency Task (ONLT) and a Lexical Decision Latency Task (LDLT). Both tasks showed RVF superiorities. On the ONLT a sex × FS × visual field interaction was obtained, with FS− females and FS+ males showing comparably smaller RVF superiorities than FS+ females and FS− males. On the LDLT an FS by Stimulus Type (word-nonword) interaction was found, FS− subjects being more RVF superior for nonword trials and FS+ subjects more RVF superior for word trials. If one compared only FS− males and females, as some studies have done, greater RVF superiorities obtained for males than females on both the ONLT and word trials of the LDLT. However, FS+ subjects showed the opposite pattern. The data support neither the simple model of FS nor sex influence on language laterality. Data aslso suggest that a history of maternal versus paternal left-handedness may affect lateralization differently in the sexes.     

关于条件推理的ERP研究

以抽象的条件命题作为实验材料,测定13名大学生在完成MP、AC、DA、MT推理（推测判断任务）和基线任务（记忆判断任务）时的事件相关电位（ERP）,初步探讨不同推理类型的脑内时程动态变化。这是使用ERP技术来研究条件推理脑机制的初步尝试。结果发现,五种任务所诱发的ERP早成分均不存在显著差异,在头皮前部的左外侧额区和左颞区,MP与DA推理与基线任务相比,均诱发一个更明显的晚期正成分（450-1100ms）,在右外侧额区则诱发一个更明显的晚期负成分（450~1100ms）;与之相反,MT与AC推理与基线任务相比,在左侧诱发一个更明显的晚期负成分（450~1100ms）,在右侧诱发一个更明显的晚期正成分（450~1100ms）,这一结果可能是由于左右脑在推理中的认知功能以及四种推理类型之间存在的差异所致,同时也表明推测过程主要激活了左右侧的前额部、颞叶等区域,基本支持Goel等人的双加工理论