ABSTRACT Sleep and wakefulness are opposite brain and body conditions that accomplish different but complementary functions. However, these opposing conditions have been combined in some animals by the adoption of a sleep/wake strategy that allows them to survive, while maintaining both an interaction with the environment at the same time as enabling brain and body recovery. They sleep with half of

ABSTRACT Bees provide a good model to investigate the evolution of lateralization. So far, most studies focused on olfactory learning and memories in tethered bees. This study investigated possible behavioural biases in free-flying buff-tailed bumblebees (Bombus terrestris) by analysing their turning decisions in a T-maze. Bees of various size were trained to associate a syrup reward with a blue target

A growing number of studies demonstrate that consistent handers, people who use their dominant hand for all or most manual tasks, are less cognitively flexible than inconsistent handers, people who use their non-dominant hands at least some of the time. A recent hypothesis suggests that differences in handedness emerged evolutionarily because populations benefited from a balance between cognitively

In the 2010s, significant progress has been made in several key areas of laterality research, including neuroimaging, genetics and comparative research. In the present article, we discuss which trends are likely to shape laterality research in the 2020s. These include, but are not limited to: (1) Finding laterality-specific solutions to the replication crisis. (2) Integrating non-W.E.I.R.D. (Western

ABSTRACT The left hemisphere is known to be generally predominant in verbal processing and the right hemisphere in non-verbal processing. We studied whether verbal and non-verbal lateralization is present in haptics by comparing discrimination performance between letters and nonsense shapes. We addressed stimulus complexity by introducing lower case letters, which are verbally identical with upper

ABSTRACT Researchers interested in hemispheric dominance frequently aim to infer latent functional differences between the hemispheres from observed lateral behavioural or brain-activation differences. To be valid, these inferences may not only rely on the observed laterality measures but also need to account for the antecedent probabilities of the studied latent classes. This fact is frequently ignored

Research shows decreased brain region activity in the right temporo-parietal junction (rTPJ) in people with migraine headache relative to headache-free controls when performing an orienting visuospatial attention task. Functional inactivation of the rTPJ has been associated with rightward performance deviations on laterality-based attention Landmark (LM) and greyscale (GRE) tasks in individuals with

People are frequently biased to use left-side information more than right-side information to inform their perceptual judgements. This research examined whether the leftward bias also applied to preferences for the arrangement of everyday consumer items. Pairs of consumer items were created where one item was more attractive than the other item. Using a two-alternative forced choice task, Experiment

Researchers have long been interested in whether lateral preference is associated with giftedness, season of birth, and/or ADHD constructs (short attention span, high level of activity, and impulsivity). The objective of this study was to examine these associations in a large, longitudinal sample of U.S. children (National Collaborative Perinatal Project (CPP), 1959–1973). Children born to women in

In order to face a constantly changing environment, animals need to be able to update their knowledge of the world on the basis of new information. Often, this means to inhibit a previously acquired response and flexibly change their behaviour to produce a new response. Here, we measured such abilities in young domestic chicks, employing a Colour Reversal Learning Task. During the acquisition phase

Until fairly late in the nineteenth century, it was held that the brain was bilaterally symmetrical. With the discovery of left-brain dominance for language, the so-called “laws of symmetry” were revoked, and asymmetry was then seen as critical to the human condition, with the left hemisphere, in particular, assuming superordinate properties. I trace this idea from the early discoveries of the late

(2020). Obituary for Dr. Marian Annett, 1931–2018. Laterality: Vol. 25, No. 4, pp. 405-412.

Recent studies indicate that individuals with consistent hand preference are more authoritarian than individuals whose preference is relatively inconsistent. We explored the role of epistemic needs in the handedness-authoritarianism relationship. Based on findings that consistent individuals are less cognitively flexible than inconsistent individuals, we hypothesized that consistent-handers would report

(2020). Reflections of a Neuropsychologist. Laterality: Vol. 25, No. 4, pp. 511-512.

Many studies have highlighted evidence of lateralized behaviours in vertebrates and invertebrates, indicating that cerebral lateralization might not be uniquely human. Flamingos, as highly social species, might represent an interesting model in the study of lateralization, as this trait appears to be useful in gregarious animals. This study aims to investigate the presence of lateralized behaviours

(2020). Right brain psychotherapy. Laterality: Vol. 25, No. 2, pp. 255-258.

Comparative studies can help understand better brain functional lateralization for manipulation and language. This study investigated and compared, for the first time, human adults' laterality for manipulation and gestures in a non-experimental social context. We analysed the manual laterality of 48 beach volleyball athletes for four frequently expressed behaviours: a complex throwing action (jump

Pitch height is thought to be mentally represented along the vertical and the horizontal axes. This is based on a well-described effect: the Spatial Pitch Association of Response Codes (SPARC) effect. A low pitch is more easily associated with a left or a low location and a high pitch with a right or a high location. While much of the evidence supports the existence of these two "mental pitch lines"

Earlier research suggested that gaze direction has an impact on cognitive processing. It is likely that horizontal gaze direction increases activation in specific areas of the contralateral cerebral hemisphere. Consistent with the lateralization of memory functions, we previously showed that shifting gaze to the left improves visuo-spatial short-term memory. In the current study, we investigated the

Studies of brain lateralization in individuals with non-specific intellectual disability and Down syndrome suggest atypical brain lateralization to speech perception. According to the biological dissociation model, the right hemisphere (RH) mediates speech perception and the left hemisphere (LH) mediates motor control in Down syndrome. The current study aimed to test, for the first time, brain lateralization

In this study, we coded art painted on rocks located in southern Africa, which was painted with a mixture of ochre, blood, and clay by the San, a Neolithic culture with no written language. These images depict a mixture of humans and animals in a variety of contexts, including (but not limited to) hunts and dances. We calculated a laterality index for the collected available art from each region, finding

As the right hemisphere is dominant for emotion processing, the left cheek expresses emotion more intensely than the right cheek. This prompts a leftward bias: people offer the left cheek to communicate emotion and viewers perceive left cheek poses as more emotive. Perceptions of trustworthiness are positively influenced by emotional expressivity, with smiling faces deemed more trustworthy than neutral

The causes of developmental stuttering, a neurodevelopmental communicative disorder, have not been elucidated to date. Neuroimaging studies suggest that atypical cerebral laterality could be one of such causal factors. Moreover, handedness, a behavioural index for cerebral laterality, has been linked to stuttering and recovery from it. However, findings are conflicting, possibly due to sample selection

Previous studies found that valence and visual half-field have an influence on word reading: Words are processed more efficiently when they evoke positive feelings and when they appear in the right visual field. In the present study we tried to address previous (contradictory) reports of an interaction between valence and visual half-field.A group of 39 right-handed undergraduates completed a lexical

Although a population bias toward right-hand preference is observed at the early stage of grasping, hand preference fluctuates in infancy. Given these fluctuations, one can wonder whether testing a young infant on a single occasion gives reliable results of its handedness. Very few studies have evaluated short-term test-retest reliability. This was the goal of this study in which 21 infants aged 9–15

Researchers have utilized reaching paradigms to measure infant handedness for more than a century. However, methods vary widely. Recent research has identified that the number of trials used in assessment is critical with the recommendation that at least 15 trials are necessary to reliably classify infants into handedness categories via statistical cutoffs. As a first step towards establishing best

In this study, we investigated age differences in manual force production to explore their neurophysiological basis. Manual pinching and gripping forces were first measured during unilateral and bilateral efforts in two groups of right-handed adults (young, n = 12, senior, n = 11). Then, transcranial magnetic stimulation (TMS) was applied to each hemisphere to assess central motor inhibition via the

Brain–computer interfaces (BCI) decode user’s intentions to control external devices. However, performance variations across individuals have limited their use to laboratory environments. Handedness could contribute to these variations, especially when motor imagery (MI) tasks are used for BCI control. To further understand how handedness affects BCI control, performance differences between two monozygotic

Age-related changes have been identified in neural and motor level. A prominent change is reduced asymmetry in cortical activation as well as motor performance. Cortical activation models have been established based on cognitive research utilizing neuroimaging techniques to explain age-related effects on neural recruitment and reduced brain asymmetry. Recently, researchers in motor behaviour attempted

The unilateral contractions procedure (i.e., squeezing a ball with one hand) supposedly enhances a wide variety of cognitive functions, from episodic recall to choking under pressure. The practicality and affordability of this procedure makes it highly appealing. But does it work? We addressed this question by testing whether intermittent and sustained unilateral contractions shifted a well-supported

(2020). Dyslexia and neuroscience: the geschwind-galaburda hypothesis 30 years later. Laterality: Vol. 25, No. 3, pp. 390-392.

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

Based on numerous findings of an abnormal laterality in schizophrenia disorder, we hypothesized that handedness and lateral preferences may affect the age at onset in schizophrenia patients. Two samples of schizophrenia patients, the first a sample of 34 right-handers and 42 left-handers and a replication set of 84 right-handers, were examined with regard to age at onset considering handedness and

Studies have found a tendency for heads in portraits to be oriented so that more of the left side than the right side of the face is visible, though it is stronger in female than in male portraits. Two studies are reported that set head orientation in the context of body and gaze orientation, and additionally look at effects of artistic medium (paintings, photographs, and drawings) and changes in the

A remarkable feature of human handedness at the population level is specialization of the hands, the right hand performing usually better than the left. This specialization might have an evolutionary advantage, because it provides the individual and population with a wider range of skill. We therefore investigated the relationships between hand skill asymmetry and potential markers of Darwinian fitness

Although olfactory laterality in canids has been demonstrated experimentally, the extent to which nostril bias occurs in "nature" is not well known. We tested whether there was olfactory laterality of untrained dogs in various off-leash dog parks within Victoria, British Columbia to manipulated scents placed at the tail base of full-size dog replica. Using video-playback, we found that of 192 separate

Handedness ontogenesis is still under debate in science. This systematic review analyzed articles regarding the theories and basis of handedness formation, highlighting the historical knowledge path that this literature underwent. Cochrane Library, LILACS, Web of Sciences, Science Direct and PubMed databases were searched. This review included review studies with handedness as the main topic. Only

Left and inconsistent hand preferences are the markers of atypical brain organization that relate with cognitive and behavioural traits as well as with developmental disorders, whereas intolerance of uncertainty is the trait of inability to bear future uncertainty that mediates anxiety disorders and depression. In the present study, relationship of hand preference with intolerance of uncertainty was

Liaison between neuroscience and education has resulted in significant advances in our understanding of the neurobiological learning requirements of individuals with reading disability, the neuroplasticity of the developing brain, and the participation of the right hemisphere in reading. Research in neural network theory and cortical oscillations suggests that the hemispheres collaborate in high-level

People exhibit consistent leftward spatial biases across a variety of tasks. However, individuals with a native reading direction other than left-to-right (LTR) show an attenuation of the leftward bias. The current study used procedurally similar tasks to examine spatial ability and aesthetic preferences in LTR and right-to-left (RTL) groups. In the spatial task participants viewed a centred rectangle

There is a great amount of research on hemispheric lateralisation for processing emotions and on the recognition of emotions across the lifespan. However, few researchers have explored the links between these two measures. This paper highlights how trends in these two research areas inform our understanding of how lateralisation for emotion processing may influence emotion recognition performance throughout

For parents anxious "lest their children should be left-handed", the American author Mary Palmer Tyler offered advice and reassurance in her 1811 child-care manual The Maternal Physician. This article provides a brief biography of Tyler and the text of her remarks, along with notes on the text and the author's sources.

People tend to display the left cheek when posing for a portrait; however, this effect does not appear to generalise to advertising. The amount of body visible in the image and the sex of the poser might also contribute to the posing bias. Portraits also exhibit lateral lighting biases, with most images being lit from the left. This effect might also be present in advertisements. A total of 2801 full-page

A bias in attention towards the dominant hand has been cited as a possible factor in the lateralisation of human bimanual coordination (Peters, 1981). A mirror was placed between the hands of 18 dextral participants performing rhythmic anti-phase movements. This set-up gave the appearance of a reflected virtual hand (moving in time with the un-occluded hand), in the same spatial location as the occluded

Previous studies of motor laterality in dogs have produced some conflicting results, with inconsistencies in lateral biases across sexes, over time, and across tasks. The current study modified published food-retrieval and tape-removal tests before applying them to 43 dogs. It showed that results derived from 50 observations of a food-retrieval task (Kong test) were consistent with 100 observations

Asymmetries in movement times of the hands in 60 healthy participants with different patterns of hand-foot dominance were investigated. Handedness and footedness were assessed by means of questionnaires and verified by simple motor tasks. Psychomotor performance was evaluated by the use of selected tests from the computerised Vienna Test System (VST, Vienna, Austria). Movement time (MT) was assessed

It has been proposed that the ratio of the second to fourth digits (2D:4D) may be a proxy of prenatal androgen exposure, such that low 2D:4D ratio is associated with high prenatal androgen exposure. The aim of the present study was to measure the 2D:4D ratio in 100 right- and non-right-handed individuals with intellectual disability of unknown idiopathic origin and compare them to a control group of

The purpose of this research was to investigate the relationship between handedness, reading skills, and reading-related cognitive processes. Although lateralised differences in brain functioning are well known, research regarding handedness, specific reading skills, and reading-related cognitive processes is ambiguous at best because handedness is often measured as a dichotomous variable rather than

We aimed to determine the functional localisation of right-left discrimination (RLD) by functional MRI (fMRI). In this study, 16 male volunteers were examined. There were three task sessions: one active and two baseline tasks. During the baseline tasks participants were instructed to show numbers with their fingers. The first baseline task was performed with the right hand, the second one with the

The lateralisation of colour processing is not well understood, although there is a reasonable amount of evidence indicating a right hemisphere bias for colour processing. Tasks that require colour naming are associated with a left hemisphere bias and it is likely that asymmetry of colour processing is influenced by task demands. It is not known whether object colour knowledge is lateralised. In the

Research has shown that persons with mixed hand preference (i.e., who report using their non-dominant hand for at least some manual activities) display an increased tendency to update beliefs in response to information inconsistent with those beliefs. This has been interpreted as reflecting the fact that the left hemisphere maintains our current beliefs while the right hemisphere evaluates and updates

The aim of the present study was to investigate if there is a possible lateralisation for ovarian cancers, to re-examine left-right asymmetry in pelvic lymph nodes distribution in patients with ovarian cancer, and to investigate if pelvic lymph node involvement by metastatic invasion of ovarian cancer cells is ipsilateral or contralateral. There was right-sided lateralisation for ovarian cancer. The

This study investigates the spatial bias of visual attention measured by a temporal order judgement (TOJ) task and the influence of a high attentional load condition in a group of dyslexic children compared to a control group with normal reading skills (each group N=10). The TOJ task (T2) was placed after a shape discrimination task (T1). In a low attentional load block participants worked only on

In the present study we assessed the contribution of the two hemispheres to the attribution of gender of faces in male and female observers. Normal and chimeric faces were presented in their canonical orientation and upside-down in a tachistoscopic paradigm. Chimeric faces were composed of two halves (left and right) obtained from photos of individuals of the same sex or from individuals of different

A series of eight studies focuses on how the avoidance system represented by neuroticism can lead to disinhibited approach tendencies. Based on research which argues that hemispheric preferences predispose the left hemisphere to fast action goal formation, and contralateral pathways between ear and brain, it is proposed that (a) people with a right ear preference will engage in fast action goal formation

The majority of people throughout the world show extreme preference for the right hand. We studied lateral bias depicted in ancient Indian sculptures dating between the 7th and 9th centuries ad. A total of 288 sculptures were selected from various excavation sites/museums and the frequencies were computed on 13 different criteria in order to see the preferential bias for hand depicted in sculptures

During fast locomotion--gallop, half-bound, bound--of quadruped mammals, the ground contact of the limbs in each pair does not alternate symmetrically. Animals using such asymmetrical gait thus choose whether the left or the right limb will contact the ground first, and this gives rise to limb preference. Here, we report that dogs (Mammalia, Carnivora) and pikas (Mammalia, Lagomorpha) prefer one forelimb

The impact of menstrual cyclicity and sex differences on dichotic listening was studied in 25 women and 20 men (aged 20-25 years). Dichotic listening was administered using consonant-vowel (CV) stimuli and tested across three attention conditions. Women were tested at two points in the menstrual cycle (Day 2-5: low oestrogen and progesterone/Low-EP; Day 18-25: high oestrogen and progesterone/High-EP)

In the past 15 to 20 years, evidence of population-level handedness in non-human primates has emerged from a plethora of studies, although considerable inconsistency is also apparent. The study reported here examined two factors that may contribute to the expression of hand preference: early rearing history and sex differences. Handedness was assessed in rhesus monkeys (Macaca mulatta) using a task