ABSTRACT There is contradictory evidence on the influence of handedness on depression and anxiety. However, few studies have investigated the relationship between handedness and rumination, which is robustly associated with both depression and anxiety. This study aimed to examine the influence of direction and consistency of handedness on rumination, considering four different classifications of handedness. The study sample included 406 participants (282 females) who attended an online survey and answered a demographic questionnaire, the Edinburgh Handedness Inventory, the Ruminative Response Scale, and the second edition of the Beck Depression Inventory. Considering four different classifications of handedness, a series of one-way ANOVAs was conducted to investigate any differences between the handedness groups. Besides, linear regression models were used to predict depression or rumination scores among the whole study sample, left-handers, and right-handers. Consistency of handedness predicted rumination among right-handers (but not left-handers), with a direct association between consistency and brooding/total rumination scores. Also, consistent left-handers and consistent right-handers showed higher brooding scores than inconsistent right-handers. Overall, the results supported the significant influence of both direction and consistency of handedness on individual differences in rumination and suggested consistent- and left-handedness as perpetuating factors for ruminative response style.

ABSTRACT For most individuals, language is predominately localized to the left hemisphere of the brain and visuospatial processing to the right. This is the typical pattern of functional lateralization. Evolutionary theories of lateralization suggest that the typical pattern is most common as it delivers a cognitive advantage. In contrast, deviations from the typical pattern may lead to poorer cognitive abilities. The aim of this systematic review was to assess the evidence for an association between patterns of language and visuospatial lateralization and measures of cognitive ability. We screened 9,122 studies, retrieved from PsycINFO, EMBASE, MEDLINE, PubMed, and Web of Science. The 17 studies that met our selection criteria revealed little evidence for an advantage of typical compared to atypical patterns of lateralization, although atypical lateralization patterns were related to worse language comprehension, spatial ability, and reading, but further research is needed to confirm this. We conclude with recommendations that future researchers recruit larger samples of atypical participants, and consider strength of lateraliation and bilaterality when analysing functional lateralization patterns.

ABSTRACT The Chimeric Face Test (CFT) is a widely used behavioral measure of degree of lateralization for emotion processing. The Pictures of Facial Affect (Ekman, 1976 [Pictures of facial affect. Consulting Psychologists Press.]) have often been used to create chimeras for this task but have widely been critiqued due to lack of ethnic diversity and small stimuli numbers. In this brief study participants (N = 45) completed two Chimeric Face Tests, one using the Pictures of Facial Affect and one using the NimStim facial stimuli (Tottenham et al., 2009 [The NimStim set of facial expressions: Judgments from untrained research participants. Psychiatry Research, 168(3), 242–249]). The laterality scores were compared across measures. The results show the two measures are related; laterality quotients showed a strong correlation between the two tasks. Participants showed a left-visual field bias on both tasks, indicative of a right-hemisphere bias for the processing of emotions. The NimStim Chimeric Face Test however was found to give a more conservative estimate of degree of lateralization. The NimStim Chimeric Face Test is discussed as a valid measure for examining lateralization for emotion processing, The extent to which different versions of the Chimeric Face Test are comparable is discussed.

ABSTRACT Laterality is considered relevant to performance in combat sports with particular emphasis being placed on fighters’ handedness and combat stance. Such approach, however, may fall too short to understand the role of laterality in sports where fighters are allowed to use their hands and feet standing and on the ground. Here, we referred to grappling sports (i) to estimate lateral preferences in selected combat situations and (ii) to test for an association between those preferences and common measures of hand and foot preference. Based on the responses of 135 experienced grapplers who participated in an online questionnaire lateral preference, at the group-level, was revealed in 12 out of 18 combat situations. At an item-level, common measures of lateral preference and grappling-specific lateral preference were related in three out of 36 conditions (footedness only, not handedness). Across items, scores in a grappling-specific laterality index were positively related with foot but not with hand preference scores. Implications for the assessment of lateral preference in combat sports and the use of item-specific terminology in this context are discussed. On a broader scale, we also elaborate on potential consequences of our findings with regard to evolutionary explanations of the maintenance of left-handedness in humans.

ABSTRACT Several factors affect the development of lateralization such as hormones and light exposure during early development. Laterality also often correlates with other behavioral traits. To examine whether there is a common mechanism underlying the development of laterality and other behaviors, we manipulated laterality by exposing embryos of the Western rainbowfish (Melatotaenia australis) to light or continuous darkness during early development and determined whether a shift in laterality was associated with a change in behavior in a novel environment test at two different ages. We found that exposing eggs to darkness led to offspring that displayed significantly less lateralized behavior in the mirror test two weeks after hatching than offspring from eggs exposed to light. Interestingly, the effects of rearing condition were lost by 3 months of age. These data suggest that exposure to light can influence laterality very early in development, but such bias can be overwritten by developmental processes post-hatch. Moreover, our manipulation of laterality apparently had no influence on exploration suggesting independent causal mechanisms. The experimental manipulation of light exposure during development could be a useful tool for enhancing individuals with a specific laterality and behavioral traits to aid future research into the causes and consequences of laterality.

ABSTRACT Handedness is a core phenotype in clinical laterality research and several different disorders such as schizophrenia and autism spectrum disorders have been linked to a higher prevalence of non-right-handedness. Moreover, subclinical personality traits like schizotypy have been linked to a higher prevalence of non-right-handedness. The association with handedness is poorly understood for generalized anxiety disorder and specific phobias, as well as for state and trait anxiety and fear of specific stimuli in nonclinical samples. Therefore, we performed a narrative review of studies investigating handedness in anxiety disorders patients and studies that compared anxiety scores between different handedness groups. Unlike schizophrenia and autism spectrum disorders, there seems to be no strong association between anxiety disorders and handedness in adult patients, except for specific phobias. Studies often had small sample sizes and therefore a high risk to report spurious findings. Similar findings were reported in most non-clinical studies. Importantly, familial handedness affects phobia risk and antenatal maternal anxiety increased the probability of mixed-handedness. This suggests that a transgenerational, developmental perspective is essential to better understand the complex interrelations between handedness and anxiety. Familial and especially maternal handedness and anxiety disorders should be integrated into future studies on handedness and anxiety whenever possible.

People tend to deviate to the right when walking through a narrow aperture (e.g., a doorway), resulting in a rightward bias in collisions. This study examines the effects of smartphone use on rightward collisions while walking. When pedestrians walk through a narrow aperture, they usually head straight to the perceived centre of the aperture, which is shifted slightly to the right, without updating the estimates. The rightward shift of the perceived centre is attributable to the rightward attentional shift in the extrapersonal space. Pedestrians using smartphones tend to fixate on the phone most of the time and thus tend not to look at their surroundings (i.e., extrapersonal space). Therefore, we predict that smartphone use will reduce rightward collisions. To test this prediction, we used a narrow-doorway task in which participants walked through a narrow doorway either with or without a smartphone. The participants with smartphones used them to perform either verbal or spatial tasks. The number of rightward collisions decreased when the participants used smartphones. The type of task had no effect on the lateral collision biases. These results were interpreted in terms of lateral attentional bias in peripersonal and extrapersonal spaces.

ABSTRACT As the percentage of right-handers increases in a state, the tightness of that state’s culture, as measured, also increases. The relations between handedness, tightness, and various COVID measures (cases per 100,000, vaccination rates, hospitalization rates, death rates, and mask wearing adherence) were examined. Left-handedness rates and tightness both marginally predicted COVID cases and significantly predicted vaccination rates (more right-handers and more tightness associated with higher COVID rates and lower vaccination rates), only left-handedness rates predicted mask wearing adherence (more left-handers associated with increased adherence), only tightness predicted death rates (more tightness associated with higher death rates), and neither handedness or tightness predicted hospitalizations. Results are discussed in terms of the connection between consistent right-handedness and decreased cognitive flexibility and its implication for sociopolitical outcomes, and implications for the framing of public health messaging are presented.

ABSTRACT The primary objective of this investigation was to explore the strategic asymmetry exhibited by the two hemispheres during semantic processing, specifically focusing on the visual recognition of homonyms. By utilizing balanced and unbalanced homonyms, we sought to ascertain whether foveal processing adheres to a specific hemisphere's strategy. In Experiment 1, we employed a visual half-field presentation paradigm to elucidate the unihemispheric strategy employed for homonym recognition. Notably, our results revealed a significant type effect, whereby responses were more accurate for unbalanced homonyms compared to balanced homonyms, particularly in the LVF/RH. This outcome suggests that the RH exhibits a stronger activation of the dominant meaning, primarily driven by frequency, while the LH concurrently activates all candidate meanings of homonyms with comparable intensity. Building upon these insights, Experiment 2 involved the presentation of both homonym types within the foveal vision, leading to the identification of a significant type effect and providing evidence for the robust utilization of the RH strategy during foveal homonym recognition. Collectively, these findings delineate an asymmetric strategy employed during semantic processing across the hemispheres, with the RH assuming a dominant role in the semantic processing of foveal words.

ABSTRACT Indications of laterall biases favouring left-handers have been found in various sports; especially interactive sports where the athletes have limited time to react to incoming objects. The aim of this study was therefore to explore whether any lateral biases exist in handball by examining 7-meter shots. A total of 6846 7-meter throws from 240 7-meter shooters across four seasons in the semi-professional Icelandic elite handball division (male and female) were analyzed. Out of the 240 7-meter shooters, of which 151 were male and 89 were female, 22% were left-handed (22% of the males and 20% of the females). The left-handed 7-meter shooters took a disproportionate number of the 7-meter shots, with left-handed shooters performing 29% of the 7-meter shots (27% in the male league and 33% in the female league). The results of a Bayesian two-level analysis indicated that left-handedness is not associated with greater success from the 7-meter line at the semi-professional level.