Laterality 

About: Laterality is an academic journal published by Taylor & Francis. The journal publishes majorly in the area(s): Laterality & Population. Over the lifetime, 1087 publications have been published receiving 21798 citations. The journal is also known as: functional laterality & lateral dominance.

Edinburgh Handedness Inventory – Short Form: A revised version based on confirmatory factor analysis

Abstract: While the Edinburgh Handedness Inventory has been widely used, there have been few studies assessing its factorial validity. There is evidence that the original instructions and response options are difficult to understand. Using simplified instructions and response options, the Edinburgh Handedness Inventory was administered on a sample of 1514 participants using an online questionnaire. In accordance with previous research, a model of the 10-item inventory had poor fit for the data. This study also detected model misspecification in the previously-proposed 7-item modification. A 4-item Edinburgh Handedness Inventory - Short Form had good model fit with items modelled as both continuous and ordinal. Despite its brevity, it showed very good reliability, factor score determinacy, and correlation with scores on the 10-item inventory. By eliminating items that were modelled with considerable measurement error, the short form alleviates the concern of the 10-item inventory over-categorising mixed handers. Evidence was found for factorial invariance across level of education, age groups, and regions (USA and Australia/New Zealand). There generally appeared to be invariance across genders for the 4-item inventory. The proposed Edinburgh Handedness Inventory - Short Form measures a single handedness factor with an inventory that has brief and simple instructions and a small number of items.

On the magnitude of laterality effects and sex differences in functional lateralities.

Abstract: In the last 20 years, the hypothesis that men and women differ in functional lateralities has been used to account for sex-related differences in verbal and spatial skills. However, this hypothesis has not been clearly supported, with some reviewers confirming it (McGlone, 1980 for example), and others rejecting it (Fairweather, 1982 for example). The purpose of the present study was to provide a definite test of this hypothesis and to estimate the magnitude of overall laterality effects by means of a meta-analytic procedure. A total of 396 significance levels from a variety of studies on functional asymmetries utilising auditory, visual, or tactile presentation of verbal or nonverbal stimuli were sampled. Results showed that laterality effects tend to be large and significant but that they are heterogeneous in the visual modality. Homogeneity was generally achieved by a partition of the studies in terms of the specific task used. The results also showed sex differences to be significant in two modalities (visual and auditory). The data indicated the presence of sex differences in favour of men in functional asymmetries. However, it appears that the findings are not resistant to the file drawer problem. The results are discussed with regard to their implications for explanations of individual differences in cognitive abilities. The relation between functional lateralities and anatomical asymmetries is also discussed.

Is there geographical variation in human handedness

Abstract: Right- and left-handed individuals are present in all cultures. However, while it is known that handedness is a heritable trait, little is known about how handedness varies between populations-and without this knowledge, the significance of the left/right polymorphism is hard to interpret. We reviewed the literature to assess the extent of geographical variation of throwing or hammering handedness. These two tasks were chosen because they are present in all known cultures (unlike, for example, writing), and make sense within the context of several adaptive theories on the origin of laterality, or maintenance of handedness polymorphism, which state that tool or weapon manipulation are pivotal. A total of 81 samples were found with primary data on throwing or hammering handedness, spanning 14 countries and concerning more than 1,214,000 individuals studied between 1922 and 1998. A global logistic regression was performed to assess the significance of the country of the study, controlling for several potentially confounding variables (date of the study, sex and age of individuals). Country always had a significant effect, consistent with substantial geographical variation of throwing and hammering handedness. Curiously, left-handedness frequency estimates for a given country were not always consistent across datasets, perhaps due to missing variables, such as educational level or socio-economic status. Results are discussed in the context of the evolution of handedness and the significance of the current polymorphism.

The divided visual field paradigm: methodological considerations.

Abstract: The divided visual field methodology has been used to examine a wide variety of lateralised processes. When conducting such studies it is important to employ a number of strict controls in order to maximise the effectiveness of the paradigm for examining the processing of stimuli by each hemisphere. The use of these controls is discussed in this paper. The following issues are discussed: selection of participants; methods of fixation control; presenting stimuli unilaterally; methods of responding; and measures that can be taken. The use of the divided visual field paradigm to examine interhemispheric cooperation is also discussed. Employing the recommended controls provides an effective and relatively easy method of examining the role of each hemisphere in the processing of stimuli.

Population lateralisation and social behaviour: a study with 16 species of fish.

Abstract: We investigated turning responses in 16 species of fish faced with a vertical-bar barrier through which a learned dummy predator was visible. Ten of these species showed a consistent lateral bias to turn preferentially to the right or to the left. Species belonging to the same family showed similar directions of lateral biases. We performed an independent test of shoaling tendency and found that all gregarious species showed population lateralisation, whereas only 40% of the nongregarious species did so. The results provide some support to the Rogers (1989) hypothesis that population lateralisation might have been developed in relation to the need to maintain coordination among individuals in behaviours associated with social life.