Factor analysis of the Home Handedness Questionnaire: Unimanual and role differentiated bimanual manipulation as separate dimensions of handedness

Handedness

This chapter offers an overview of the literature on human handedness and its assessment in clinical neurologic practice and research. There are two major forms of handedness: hand preference, which describes a subjective preference to use one hand over the other for skilled motor activities like writing, and hand skill, which describes objectively measured mother skill. This chapter gives an overview of widely used questionnaires and tests to assess hand preference and hand skill, as well as suggestions on how to determine handedness categories such as left-handed, right-handed, and mixed-handed based on the results of these questionnaires and tests. Handedness is just one form of hemispheric asymmetry in the human motor system, and the chapter also provides an overview of its association with other motor asymmetries such as footedness. Moreover, the associations of handedness with functional brain activation as well as with structural markers on the cortical, subcortical, cerebellar, and spinal levels are discussed. Furthermore, the potential relevance of handedness retraining for clinical neurologic research and the association of handedness and cognitive abilities are discussed. The chapter concludes with an outlook on the critical importance of including handedness in clinical neurologic research and practice.

Latent dimensions of brain asymmetry

Functional lateralization represents a fundamental aspect of brain organization, where certain cognitive functions are specialized in one hemisphere over the other. Deviations from typical patterns of lateralization often manifest in various brain disorders, such as autism spectrum disorder, schizophrenia, and dyslexia. However, despite its importance, uncovering the intrinsic properties of brain lateralization and its underlying structural basis remains challenging. On the one hand, functional lateralization has long been oversimplified, often reduced to a unidimensional perspective. For instance, individuals are sometimes labeled as left-brained or right-brained based on specific behavioral measures like handedness and language lateralization. Such a perspective disregards the nuanced subtypes of lateralization, each potentially attributed to distinct factors and associated with unique functional correlates. On the other hand, traditional studies of brain structural asymmetry have typically focused on localized analyses of homologous regions in the two hemispheres. This perspective fails to capture the inherent interplay between brain regions, resulting in an overly complex depiction of structural asymmetry. Such conceptual and methodological discrepancies between studies of functional lateralization and structural asymmetry pose significant obstacles to establishing meaningful links between them. To address this gap, a shift toward uncovering the dimensional structure of brain asymmetry has been proposed. This chapter introduces the concept of latent dimensions of brain asymmetry and provides an up-to-date overview of studies regarding dimensions of functional lateralization and structural asymmetry in the human brain. By transcending the traditional analysis and employing multivariate pattern techniques, these studies offer valuable insights into our understanding of the intricate organizational principles governing the human brain's lateralized functions.

Handedness in Alzheimer's disease: A systematic review

Handedness has traditionally been employed as a proxy of brain lateralization in research. Alzheimer's disease (AD) manifests as a neurodegenerative disorder characterized by impairments across various neuropsychological functions, including visuospatial and language, many of which exhibit lateralization in the human brain. While previous studies have investigated the relationship between AD and handedness, findings have been inconsistent. This article aims to provide an up-to-date overview of studies investigating hand preference in AD and the subtypes, specifically early- and late-onset AD. Through a synthesis of these studies, we conclude that handedness currently lacks utility as a diagnostic biomarker for AD and its subtypes, and this is further supported by the meta-analytic results based on data from over 10,000 AD patients. We emphasize the necessity for future research endeavors, particularly those leveraging advanced neuroimaging techniques to explore the role of brain asymmetry in AD.

Fifty Years of Handedness Research: A Neurological and Methodological Update

Handedness, a complex human aspect that reflects the functional lateralization of the hemispheres, also interacts with the immune system. This study aimed to expand the knowledge of the lateralization of hand, foot, and eye activities in patients with immune-mediated (IM) or other (noIM) neurological diseases and to clarify the properties of the Edinburgh Handedness Inventory (EHI) in an Italian population. Three hundred thirty-four patients with IM or noIM diseases affecting the brain or spine and peripheral nervous system were interviewed about stressful events preceding the disease, subjective handedness, and familiarity for left-handedness or ambidexterity. The patients and 40 healthy subjects underwent EHI examination. In the whole group of participants, 24 items of the EHI were classified into five factors (Hand Transitive, Hand Refined, Hand Median, Foot, Eye), demonstrating good reliability and validity. Chronological age had a significant influence on hand and foot EHI factors and the laterality quotient (LQ), particularly on writing and painting. In the patient groups, EHI factors and the LQ were also predicted by age of disease onset, duration of disease, and family history of left-handedness or ambidexterity. No differences were found between patients and healthy subjects, but pencil use scored significantly lower in patients with IM diseases than in those with noIM brain diseases. These results demonstrate that the lateralization of hand and foot activities is not a fixed human aspect, but that it can change throughout life, especially for abstract and symbolic activities. Chronic neurological diseases can cause changes in handedness. This may explain why, unlike systemic immunological diseases, IM neurological diseases are not closely associated with left-handedness. In these patients, the long version of the EHI is appropriate for determining the lateralization of body activities to contextualize the neurological picture; therefore, these findings extend the Italian normative data sets.

Does the Degree and/or Direction of Handedness in Children With Developmental Coordination Disorder Influence Motor and Cognitive Performance? A Pilot Study

Research has shown that nonright-handedness in children with developmental coordination disorder (DCD) is associated with poorer motor and cognitive performance. This study investigated the influence of degree and direction of handedness on performance using the Home Handedness Questionnaire, the Hit-the-Dot test, the Movement Assessment Battery for Children, and the digital Trail-Making Test. Eighteen children with DCD and 21 typically developing children aged 8–12 years participated in this study. The distribution of degree and direction of handedness in the group of DCD children were not different from that found in the typically developing group. In the Hit-the-Dot test, typically developing children significantly performed better than children with DCD, no matter which hand was dominant or to which degree. A significant inconsistent-handed advantage in the subdomain balance was found for children with DCD. Inconsistent handedness also seems to be an advantage for children with DCD on the digital Trail-Making Test performance. The relationship between the subcategories of the Movement Assessment Battery for Children and the digital Trail-Making Test part B is stronger for consistent than for inconsistent handedness. Our findings suggest that children with DCD and inconsistent handedness might benefit from greater crosstalk across hemispheres. In addition, these predispositions can be reinforced or discouraged throughout development and via occupational therapy.

Examining Variations Between Everyday Life Handedness and Lateral Preferences for Sport-Specific Skills in Children

Purpose: This study aimed to analyze both sport-specific lateral preferences and handedness for everyday life tasks among school-aged children. Method: A total of 533 children (254 males and 279 females) aged 6 to 15 years old were assessed. Children's handedness was determined according to the laterality score from Edinburgh Handedness Inventory (EHI), while lateral preferences were assessed for 16 different sport-specific tasks. Results: The percentage of children with a left hand preference was lower for unilateral (10.5-14.3%) than for bilateral (19.5-31.7%) tasks. An increased prevalence of left-sided preference was also obtained for foot tasks (13.3-26.8%) and rotation along the vertical axis (28.5%). Similarly, hand preference for unilateral sport-specific tasks and EHI scores were largely correlated (r = 0.551-0.630), while these correlations were lower for bilateral hand tasks (r = 0.148-0.418), foot tasks (r = 0.201-0.386) and rotation preference (r = 0.129). Moreover, left-handed children evidenced less lateralized behavior for sport-specific tasks than right-handed children. Conclusions: The current study has shown that sport-specific lateral preferences and their correlations with handedness vary considerably depending on the task and individual characteristics in developmental ages. These findings emphasize the relevance of task-specific assessments of lateral preferences when looking at sports skills during childhood.

Insights Into Human and Nonhuman Primate Handedness From Measuring Both Hands

Handedness is part of our everyday lives, but where does it come from? Researchers studying nonhuman primates and young children have approached this question from different perspectives—evolutionary and developmental, respectively. Their work converges on the conclusion that measurement matters in the science of handedness. Coming to a consensus on assessment will guide future research into the origins of handedness. A candidate behavior for promoting multidisciplinary comparison is role-differentiated bimanual manipulation.

New data on the validity of the Fazio Laterality Inventory

The Fazio Laterality Inventory (FLI) is a recent measure of handedness. Although initially validated, there is still a lack of studies assessing its psychometric properties in samples outside the USA. The present study explores the validity of the Polish adaptation of the FLI. We used data gathered from a convenience sample of 727 participants. They completed the FLI and the Edinburgh Handedness Inventory to establish concurrent validity. Confirmatory factor analysis was used to investigate the factor structure of the FLI. In addition, an Item Response Theory (IRT) model for continuous item scores was also used to identify the discrimination and difficulty parameters of the FLI items. The Polish version of the FLI was characterized by good reliability indices and has high concurrent validity with the Edinburgh Handedness Inventory. We identified a bi-factorial structure for the questionnaire. The IRT analyses showed that the FLI items have good discrimination and difficulty parameters. Our study provides new insights into the properties of the Fazio Laterality Inventory.

A Novel Perspective for Examining and Comparing Real and Virtual Test Tasks Performed by the Dominant and Non-Dominant Hand in Healthy Adults

This study presents a novel perspective for the study of functional lateralization in a virtual reality environment. In the model study of handedness, the recognition of the dominant and non-dominant hand in real and virtual conditions was assessed using selected tests, such as a real light exposure test of Piórkowski’s apparatus and classical clinical tests, as well as virtual test tasks, in healthy adults. Statistically significant differences between the dominant and non-dominant hand were observed for tests carried out both in classical conditions and the virtual environment. The results and findings of other studies suggest that the virtual reality approach is a very promising and sensitive tool in the research on functional asymmetries in healthy and disease for motor skills and cognition processes.

Preschool language ability is predicted by toddler hand preference trajectories

Prior work has found links between consistency in toddler handedness for the fine motor skill role-differentiated bimanual manipulation (RDBM), and language development at 2 and 3 years of age. The current study investigated whether consistency in handedness from 18 to 24 months (N = 90) for RDBM predicts receptive and expressive language abilities assessed using the Preschool Language Scales 5th edition (PLS-5) at 5 years old. Latent class growth analyses identified 3 stable RDBM hand preference trajectories: a left hand preference with moderate right hand use (left-moderate right), a right hand preference with moderate left hand use (right-moderate left), and a right hand preference with only mild left hand use (right-mild left). At 5 years of age, children with a right-mild left handedness trajectory as toddlers scored significantly higher on receptive and expressive language abilities compared to children with a left-moderate right hand preference. Children with a right-mild left hand preference for RDBM also scored significantly higher on receptive language abilities compared to children with a right-moderate left RDBM hand preference. Children with left-moderate right and children with a right-moderate left hand preference for RDBM as toddlers did not differ in receptive or expressive language abilities at 5 years. Results indicate that individual differences in hand preference consistency for fine motor skill in toddlerhood have cascading effects on language outcomes into the preschool years. (PsycINFO Database Record (c) 2020 APA, all rights reserved).