When is handedness evident

Keep him confidently crafting with his own pair of lefty scissors. As a righty, modeling these tasks with your left hand can be a brain puzzler, but you actually have the advantage here! Our teachers help every child build the confidence they need to try new things and explore the world around them.

Many a kitchen pot and coffee mug are made with handles for right-handed orientation a subtle distinction you righties might not ever have noticed. Right hands are presented for hand shakes, not left hands. KinderCare aims to protect your privacy online the way we protect your family in person, with care and caution. To improve the website experience, this site uses cookies as described in our Cookie Notice.

Click allow to consent to the use of this technology on our site. Such early differences in brain development should result in different trajectories of psychological development. We present evidence that children with consistent early hand preferences exhibit advanced patterns of cognitive development as compared to children who develop a hand preference later. Differences in the developmental trajectory of hand preference are predictive of developmental differences in language, object management skills, and tool-use skills.

For the last four decades, one of us GFM has been investigating the factors affecting the development of infant hand-use preferences as a means of understanding how infant sensorimotor experiences contribute to the development of hemispheric differences in language processing cf. The theoretical foundation of this work was derived, in part, from theories of Piaget and Bruner , which proposed that infant sensorimotor experiences formed the foundation of symbol formation, language skill, concept formation, and reasoning.

Also, developmental psychobiological evidence about how nervous system functioning could be shaped by early experience was used to support the notion that infant hand preferences could shape functional lateralization of the hemispheres Michel, , Since most neuropsychological research was, and is, conducted within the framework that hemispheric specialization of function derives from gene controlled differences in the structural organization of the two hemispheres, hand preference and related cognitive functions are often considered to be derivative of hemispheric specialization rather than to be contributors to it.

However, in the last decade, some forms of embodiment theory e. Certain forms of embodiment theory e. Infant vocalizations, facial expressions, and body postures as sensorimotor actions elicit actions from social companions, which provide the developing infant with information about the rules of social-relational engagement.

This is similar to how the manipulation of objects reveals object properties, their relations, and rules of combination. How infants engage with these aspects of their environment sculpts their brain functioning and structure Boulenger et al.

Thus, if there are group differences in such patterns of engagement, then there ought to be group differences in cognitive and social abilities. One way of testing whether such engagements with objects shape cognitive development would be to compare the cognitive development of groups of individuals who engage the world differently during infancy.

We propose that the development of infant hand preferences creates groups of infants who engage the world differently and hence, they should develop differences in cognitive functioning. We briefly review some of our studies which demonstrate that consistent infant hand preferences predict developmental advances in language development, tool-use, and objects construction skill. Hand preferences in adults are related to differences in hemispheric specialization for language skills e.

Moreover, apparently atypical hand preference development seems to be related to nearly every mental and medical health issue e. Consequently, some investigators have argued that examination of the cognitive and social abilities of different hand preference groups is the perfect test for evaluating embodiment theory e.

Hand preference represents different patterns of hemispheric specialization and such specialization may be relevant for the manifestation of specific aspects of cognitive, social, and emotional functioning. Therefore, the development of hand preference ought to relate to the typical and atypical development of many psychological functions. However, before we can understand how hand preferences could contribute to variability in embodied cognitive experiences, we first must understand how hand preferences develop.

Hand preference is the product of multifaceted developmental processes that begin before birth and expand during early infancy Michel et al. We have found that hand preferences are developing in a cascading fashion with preferences for earlier developing manual skills e. We observed that a hand preference for acquiring objects starts manifesting before the age of 6 months, becomes prominent during 6—12 month period, and declines thereafter Michel, ; Ferre et al.

Also, although unimanual manipulation skills develop by 7—8 months, only by 10—11 months of age do infants exhibit a hand preference for unimanual manipulation and that preference matches the preference for acquisition Campbell et al. By 13—14 months of age, there is a significant increase in hand preferences for role-differentiated bimanual manipulation RDBM, Babik and Michel, A consistent hand preference for RDBM likely influences the development of hand preference for tool-use, since RDBM is an object manipulation pattern characteristic of most actions involved in tool construction and use throughout the life-span Vauclair, Although a right hand preference predominates in all infant manual skills, the hand preferences appear to be distributed continuously across infants similarly to adult hand preferences, Annett, In part, this may be a consequence of a maternal influence on the development of infant hand preferences Harkins and Michel, ; Michel, , ; Mundale, , unpublished.

In contrast, although left-handed mothers use their left hand more when playing with their infants, the difference in their hand use is small compared to the overwhelming use of the right hand by right-handed mothers.

Indeed, infants initially manifesting left-hand preference for acquiring objects who had right-hand preferring mothers significantly reduced their left-hand preference by 11 months; whereas infants initially manifesting right-hand preference who had right-hand preferring mothers strengthened their right-hand preference by 11 months Michel, The expression of infant hand preferences reflects the consequences of an immature but rapidly developing nervous system and expression can vary according to such factors as circadian rhythm, situational arousal, and the development of other neuromotor abilities, such as postural control and locomotion Corbetta and Thelen, ; Babik et al.

Moreover, the identification of a preference appears to be sensitive to various assessment procedures and conditions Campbell et al. Therefore, assessment of infant hand preferences requires longitudinal designs using tasks that are relatively similar, across age, in the manual challenge that they present for the infant.

Moreover, it is incorporated into all other manual skills involving object manipulation construction of objects and tool use. A hand preference in reaching and object contact predicts the hand preference in object acquisition Michel and Harkins, and the hand preference for acquiring objects predicts the hand preference for unimanual object manipulation Hinojosa et al.

Thus, early-developing hand preference for object acquisition is pivotal for the development of hand preference for other more sophisticated manual skills. We hypothesized that there ought to be consistent developmental trajectories for object acquisition hand preference despite some variation across assessment ages. Nine monthly assessments during the 6—14 month period permitted reliable identification of four latent groups according to their pattern of developmental trajectories using group based trajectory modeling GBTM, Nagin, ; Michel et al.

Infants with a right preference have established that preference by 6 months of age and maintain it for the next 9 months with a slight decrease in right hand use by 13 and 14 months.

Infants with a left preference had not established that preference before 8 months of age, but maintain it thereafter. Infants with a trend toward a right preference start at 6 months without a preference but have established a right preference by 14 months. Those infants without a hand preference maintain that throughout the 6—14 month period. Of course, the number of groups identified is less important than the recognition that it is only by the collection of such longitudinal data that consistencies across assessment periods can be identified.

It is those consistencies of preference that reflect the operation of neural mechanisms that ought to contribute to the development of other mechanisms associated with cognitive functioning. Other chapters in Help Me Understand Genetics. Genetics Home Reference has merged with MedlinePlus. Learn more. The information on this site should not be used as a substitute for professional medical care or advice.

Contact a health care provider if you have questions about your health. Is handedness determined by genetics? From Genetics Home Reference. Topics in the Genetics and Human Traits chapter Are fingerprints determined by genetics? Is eye color determined by genetics? Is intelligence determined by genetics?

Is the probability of having twins determined by genetics? Is hair texture determined by genetics? Is hair color determined by genetics? Is height determined by genetics? All users are urged to always seek advice from a registered health care professional for diagnosis and answers to their medical questions and to ascertain whether the particular therapy, service, product or treatment described on the website is suitable in their circumstances.

The State of Victoria and the Department of Health shall not bear any liability for reliance by any user on the materials contained on this website. Skip to main content. Babies and toddlers Home Babies and toddlers Actions for this page Listen Print. Summary Read the full fact sheet. On this page. Causes of left-handedness The development of preferred handedness Researchers still looking for answers Cross laterality explained Problems for left-handed people Advantages for left-handed people Where to get help.

Causes of left-handedness Just why one in 10 people favour their left hand is a mystery. Theories include: Genes — perhaps genetic factors predispose a child to favour the right hand. A single gene might be passed from parents to children to influence which hand a child favours.

If a particular version of this gene is inherited, the child may be more likely to be left-handed, depending on reinforcement and other environmental influences. Sex — slightly more boys than girls are left-handed. This suggests to some researchers that the male hormone testosterone has an influence on right and left-handedness.

Fetal development — some researchers believe that handedness has more of an environmental influence than genetic. They propose that environmental factors in the womb including exposure to hormones may influence whether we favour the right or left hand later in life.