Degree of asymmetry in lateral preferences: eye, foot, ear

Inventories of Human Lateral Preference: A Systematic Review

There are a variety of inventories available to evaluate human lateral preference, but no previous review has systematically analyzed and compared them. We conducted a systematic literature review to identify these inventories and describe their characteristics (e.g., dimensions, scales, tasks, psychometric properties). We included 26 articles, each presenting a different inventory to assess lateral preference, published between 1900 and 2022, selected from the following databases: PubMed, SportDiscus, APA PsycNET, and Web of Science. These inventories analyzed tasks performed in everyday life (domestic, work-related, sports, and leisure/recreation activities), covering hand, foot, hearing, visual and other non-usual lateral preference dimensions, such as trunk and head. Most inventories classified individuals based on the direction (left, indifferent or right preference) and degree (consistent or moderate) of laterality. However, many of the reviewed inventories lack established psychometric verification in their original publication, such as validity, reliability, responsiveness, and practical applicability. Inventories also presented tasks that may be specific to a given cultural setting, limiting their application across different countries. Based on these findings, we provide a comprehensive guide for researchers to select a lateral preference assessment tool, but also advocate for a new inventory with a broader approach, containing more than one dimension of lateral preference (i.e., not only handedness) and tasks that are common to different cultures to enhance practical applicability worldwide.

The development of hand, foot, trunk, hearing, and visual lateral preference throughout the lifespan

This research investigated the developmental process of five lateral preference dimensions (hand, foot, trunk, hearing, and visual preference). A total of 1236 volunteers participated in this study, divided into five age groups: 07-12 (n = 247); 13-17 (n = 234); 18-30 (n = 227); 31-60 (n = 225); and 61-90 years old (n = 303). Lateral preference was assessed via questionnaire with the Global Lateral Preference Inventory. By assessing the degree and direction of lateral preference in different ages, our results revealed a pattern of lateralization strengthening with aging in all the analyzed dimensions. We also verified significant correlation between hand preference and the other dimensions for all age groups, but correlation was stronger in the 7-12 group for all correlation pairs. Our results lead to the suggestion of an underlying general lateralization process in early ages (7-12 years old) followed by specific developmental trajectories of each preference dimension (13 years forward), likely startled by hemisphere and functional specialization related to innate developmental patterns of neural structures and social/environmental influences.

Four meta-analyses across 164 studies on atypical footedness prevalence and its relation to handedness

Human lateral preferences, such as handedness and footedness, have interested researchers for decades due to their pronounced asymmetries at the population level. While there are good estimates on the prevalence of handedness in the population, there is no large-scale estimation on the prevalence of footedness. Furthermore, the relationship between footedness and handedness still remains elusive. Here, we conducted meta-analyses with four different classification systems for footedness on 145,135 individuals across 164 studies including new data from the ALSPAC cohort. The study aimed to determine a reliable point estimate of footedness, to study the association between footedness and handedness, and to investigate moderating factors influencing footedness. We showed that the prevalence of atypical footedness ranges between 12.10% using the most conservative criterion of left-footedness to 23.7% including all left- and mixed-footers as a single non-right category. As many as 60.1% of left-handers were left-footed whereas only 3.2% of right-handers were left-footed. Males were 4.1% more often non-right-footed compared to females. Individuals with psychiatric and neurodevelopmental disorders exhibited a higher prevalence of non-right-footedness. Furthermore, the presence of mixed-footedness was higher in children compared to adults and left-footedness was increased in athletes compared to the general population. Finally, we showed that footedness is only marginally influenced by cultural and social factors, which play a crucial role in the determination of handedness. Overall, this study provides new and useful reference data for laterality research. Furthermore, the data suggest that footedness is a valuable phenotype for the study of lateral motor biases, its underlying genetics and neurodevelopment.

Asymmetries in social touch-motor and emotional biases on lateral preferences in embracing, cradling and kissing

In human social interaction, affective touch plays an integral role to communicate intentions and emotions. Three of the most important forms of social touch are embracing, cradling and kissing. These behaviours have been demonstrated to be lateralized, but the underlying mechanisms are still not well understood. Both motor and emotive biases have been suggested to affect laterality of social touch. We aimed to systematically investigate how motor preferences and emotive biases influence the lateralization of embracing, cradling and kissing within the same sample. Participants performed all three forms of social touch in neutral, positive and negative emotional conditions. Like a previous study, we found a rightward bias for embracing that was modulated by both motor preferences and the emotional content of the situation. Kissing and cradling were not influenced by motor preferences. In general, a negative emotional connotation of the situation led to a reduction of lateral biases in social touch, independent of the individual direction.

Mental representation of space: Insights from an oblique distribution of hallucinations

Three-dimensional spatial distributions of hypnagogic and hypnopompic hallucinations associated with sleep paralysis were used to investigate the internal representation of space. Left-right asymmetries in human preferences and abilities are well established. Parallel effects are also observed as lower-upper asymmetries. These parallels could reflect common underlying mechanisms or additive effects of independently evolved horizontal and vertical asymmetries. This study adds to the growing literature on multidimensional spatial biases in a context free from the influence of task-related factors. We present evidence of an oblique bias in the projection of both sensory and motor hallucinations toward lower-left and especially upper-right external space exceeding that accounted for by an additive model of separate horizontal and vertical biases. These observations are consistent with theories regarding a systematic functional relation of hemispheric with ventral and dorsal cerebral organization.

Quantitative assessment of five behavioural laterality measures: distributions of scores and intercorrelations among right-handers

Five behavioural laterality measures (degree of right-handedness, ear dominance, ocular dominance, line bisection performance, and lateral preference as assessed by preferred direction of conjugate lateral eye movements) were analysed in 1171 right-handers by merging data from 15 different samples. All laterality aspects were assessed quantitatively by using well controlled performance measures instead of questionnaires. The distributions and intercorrelations of the measures as well as their test-retest reliabilities were examined. Results show moderately high reliabilities for all measures, and clearly demonstrate considerable variability among dextrals in the direction and magnitude of the obtained behavioural laterality measures. Most importantly, independence of the different measures questions some common assumptions in laterality research. It seems unlikely, for instance, that handedness and other aspects of laterality may be a product of one single underlying mechanism of brain lateralisation.

Laterality of hand, foot, eye, and ear in twins

Information on handedness, footedness, eyedness, and earedness was collected from 33 monozygotic (MZ) twin pairs and 67 dizygotic (DZ) twin pairs. The incidence of nonright-sidedness in the twins is not higher than that reported in the literature for singletons. Similar results are found for the other lateralities. The results of assessing handedness with preference tests do not differ from those carried out with performance tests. There are no differences in incidence of nonright-sidedness between MZ and DZ twins. The concordance of lateralities is similar in MZ and DZ twins. The proportions of Right-Right, Right-Nonright, and Nonright-Nonright pairs in both groups of twins show a binomial distribution. The present results do not confirm a genetic hypothesis of determination of sidedness in humans and are comparable with the results obtained by other twin studies.

Eye-hand preference dissociation in obsessive-compulsive disorder and dyslexia

Dyslexia may be a development disturbance in which there are alterations in visual-spatial and visual-motor processing, while obsessive-compulsive disorder (OCD) is a psychiatric disease in which there are alterations in memory, executive function, and visual-spatial processing. Our hypothesis is that these disturbances may be, at least partially, the result of a crossed eye and hand preference. In the present study 16 controls, 20 OCD (DSM-IV criteria) and 13 dyslexic adults (Brazilian Dyslexia Association criteria) were included. All had a neurological examination, the Yale-Brown scale for obsessive-compulsive symptoms application and the Zazzó evaluation for laterality, abridged by Granjon. Results showed a right hand preference for 100% of controls, 84.6% of dyslexics, and 75% of OCD patients and a right eye preference for 73.3% of controls, 69.2% of dyslexics, and 35% of OCD patients. The left eye preference was significantly higher in OCD when compared with the two other groups (p = 0.01) and the left hand preference of OCD patients (25%) was also significant when compared to Brazilian population (4%) or British population (4.5%). It is possible that this crossed preference may be partially the reason for visual-spatial and constructive disturbances observed in OCD.

Side bias and accidents: are they related?

This study purports to examine the role of different forms of side bias, handedness, footedness, eyedness, and earedness, in eliciting accident-proneness in individuals. A representative sample (N = 150) was administered a Side Bias Questionnaire (Handedness: 22 items, footedness: 5 items, eyedness: 5 items, earedness: 5 items) to ascertain their preferential bias. The questionnaire also required subjects to report the number of accidents committed during their lifetime while performing activities like sports, driving, household work, etc., that required attention of medical professionals. Regression analysis of data indicated that accident-prone behavior was significantly predicted from handedness. Analysis of variance, 3 (Accident groups: low, moderate, high) x 4 (Side bias: hand, foot, eye, ear), indicated that 'mixed' handers committed more accidents as compared with clear handers. The other forms of side bias, foot, ear, and eye were unrelated to frequency of accidents.

Earedness and handedness: distribution in a German sample with some family data

There are only few data on the relative contribution of genetical factors to ear preference ("earedness"). We studied the distribution of earedness and handedness in a sample of 292 families and 36 offspring pairs. The incidence of nonright-earedness was found to be 35% and was not related to age or gender. In the same sample the incidence of nonright-handedness amounted to about 9% and was characterized by a significant prevalence in men. The distribution of handedness did not differ significantly between parents and children. We found that children's earedness and handedness were related to parental preferences. However, no paternal or maternal effect was found. The frequency of left-earedness and left-handedness of children is directly proportional to the number of left-sided parents. These results suggest that the direction of ear preference and handedness is genetically determined. But there is no genetic association between handedness and earedness.

Some aspects of earedness--the validity and reliability of self-report items

In contrast to the extensive literature on hand, foot, and eye preferences there are only a few studies concerning ear preference. From a review of 27 studies 13 items (Stopwatch, Telephone receiver, Tablecloth, Head movement, Wall, Drawer, Wall phone, Heartbeat, Door, Earphone, Box, Pocket radio, Voice) were identified in the measurements of ear preference. In a series of investigations, these self-report items were validated with respect to individual behavioural measures and test-retest reliabilities were obtained over 1 mo. and 1 yr. for earedness. These data indicate that a questionnaire composed of these items could be a valid and reliable method for the assessment of various forms of ear preference, but there are several differences among the items in validity and reliability.

Lateral preferences in a German population

There are only a few studies in the literature concerning all four lateral preferences (handedness, footedness, eyedness, earedness) and presenting their interrelationships. Porac and Coren's 1981 inventory was used to assess hand, foot, eye, and ear preference in a German sample of 506 men and 430 women. A right sided preference was found for hand, foot, eye, and ear preference among 91%, 74%, 66%, and 63% of the sample, respectively. More men were left-handed and left-footed than women. There were no significant sex differences for eyedness and earedness. Correlations ranged from .22 between hand and eye laterality to .44 between hand and foot laterality.