In considering creativity or creative ability, there seems to be increasing evidence that these abilities might be structurally underpinned by adaptations of the brain, and evidence suggests that such brain adaptations might differ among individuals on the basis of handedness. Studies would be of interest, as an increase in right-temporal-parietal structural anatomy of DTI (Diffusion Tensor Imaging) measures has been found among left-handers that is correlated with respective advantages in creativity [1]. Alongside potentially important implications for creativity research, the findings might also have implications for understanding and neurobiological modeling structural basis of other cognitive abilities.
1. Introduction
Goodness-of-fit was shown to be strongly predictive of similarity-tone and harmony, and higher notes, such as semitones, tend to be viewed as more dissonant in all musical pieces, regardless of culture. A broad unsurprising structural distinction between left and right handers was detected with respect to the central sulcus, despite inconsistent findings in the literature regarding handedness (e.g. as either pre or post). Research has indicated both direct better performance of left-handers in creativity tasks (e.g. Remote Associates Test), and indirect involvement of handedness as a covariant factor in the neuroimaging investigation of creativity which has shown within hemisphere (e.g. right lateralized prefrontal activation) differences [2].
2. Understanding Left-Handedness
Left-handedness is a term used to describe people who have a preference for using the left hand for tasks such as writing, brushing teeth, and throwing [2]. Handedness is a common trait among humans and most common hand preference is right-handedness. On the other hand, people who are equally adept with either hand or those who have a preference for using the right hand are identified as ambidextrous or right-handed respectively. Left-handedness is a relatively rare occurrence. It is estimated that about 10% of the population is left-handed [3].
The term left-handedness has no single definition. Some investigators have used self-reported items whereas others have measured hand preference using a battery of tasks such as fetching, catching, throwing and tapping. Due to such variations in measurement of stereotyping, left-handedness has been defined rigidly using Becker’s verbal definition. Becker’s verbal definition was further supplemented by a third criteria, performance, that indicates an absolute over left hand such as score of 50, 60 or even 70 for left hand on a maneuverability test of detecting and inserting upright and inverted pegs into holes. The combination of these three criteria provides a more stringent bases for being classified as left-handed. That is, a left-hander must satisfy all three clauses of Becker’s verbal definition(s). First, he should identify and report against the dominant use of his left hand for actions like writing, eating, cutting or brushing teeth, etc. Second, this indicated hand preference should be consistent with the majority of acts using the left hand for at least 75% of the occasions. Third, alternatively, the hand preference persists with the dominant use of the left hand across development without reversal of initial dominant hand preference up to adulthood.
2.1. Definition and Prevalence
There is still no universal consensus among researchers, but left-handedness is generally defined as a preference or dominance of the left hand in performing daily activities such as writing and eating, leading to the development of cortical pathways and networks necessary for the fine-motor skills associated with the left hand. It is estimated that approximately 10 percent of the world population is left-handed. In addition, 30 to 40% may be classified as ambidextrous. Disregarding the left-handed in this description is therefore risky as it involves omitting the potential contributions of creative processes and imaginative faculties that might enrich our current fund of understanding in many areas, notably art and characters in novels. Indeed, left-handed complementary characters have been documented in literature, such as Sherlock Holmes and James Bond [2].
Research shows that left-handers comprise an interesting population that has received public attention throughout history and can be considered good subjects for creativity studies. Historically, left-handed individuals proliferated in virtually all societies, although the degree of persecution they endured varied widely. The Roman Law of the Twelve Tables decreed that left-handed children had to be put to death. At the present time, different cultures worldwide hold various attitudes towards left-handedness. Some view it as a gift or a sign of superiority, acknowledging their organizational, political, and leadership skills. Others, however, consider them atavistic and accuse them of dishonest activities. For example, left-handed Spanish prosecutors are called to give the oath on the Bible in reverse. Recent surveys across the world indicate a general fall in the number of left-handed children forced to write with the right hand, signaling increased tolerance of this trait [3].
2.2. Genetics and Development
Most people have a strong preference for either the right or left hand when carrying out daily tasks, which is a reflection of the lateralization of the two sides of the human brain [4]. Psychomotor activities such as writing, eating or brushing the teeth are mostly performed using the dominant hand. The left and right sides of the human brain are specialized for different kinds of information processing, and much of our cognition is lateralized to one side or the other. Thus, this motor asymmetry is also very likely to be accompanied by behavioral and cognitive differences between left- and right-handers [2]. Left-handedness is a reflection of nervous system lateralization, just as right-handedness is. This tends to be overlooked because of the dominance of right-handedness in the population. However, roughly ten percent of people are mixed- or left-handed. Individuals with left-handedness are often thought to have superior mathematical and spatial abilities, as well as enhanced creativity. These, along with other differences in cognition and behavioral style, might be due to differences in the structure and function of the left and right sides of the brain.
Handedness has a strong genetic component. Although it is well known that most people are right-handed, no consensus has been reached over the underlying mechanisms. Identifying brain structural correlates of handedness may prove useful for genetic studies of cerebral asymmetries, as well as providing new avenues for the study of relations between handedness, cerebral lateralization and cognition. Handedness is perhaps the most overt reflection of lateralization of the central nervous system in humans. It has been known for centuries that right-handedness predominates in human populations. This motor asymmetry is observable at least as early during human development as 15 weeks of gestation, and is preceded by asymmetries of arm movements even earlier. The tendency toward right handedness has apparently been present throughout human history, and across cultures and continents. It is widely accepted that genetic variation plays a role in causing variation in handedness.
3. Brain Structure and Function in Left-Handers
The function of the whole human brain is divided between its two hemispheres. This division is based on a number of observable facts. First, movement, touch and vision of the right side of the body are mostly processed by the left hemisphere, while movement, touch and vision of the left side of the body are mostly processed by the right hemisphere [2]. This clearly defines the so-called specialization of function between the two hemispheres. The left hemisphere is better at processing language, while the right hemisphere outperforms the left in context analysis. In normal healthy people, this specialization is accompanied by an anatomical asymmetry. The planum temporale is bigger in the left than in the right hemisphere. The same statistical lateralization of handedness and asymmetry of the brain is observed in monkeys. In search for ultimate causes of human handedness in ancestral species, an alternative pathway based on social factors has been proposed. This would base increased fitness for the whole pack on a norm for lateralization achieved by brain evolution as a side effect. According to this view, these side effects happened in various domains due to left-coordination of one specialized verbal brain. Results are presented on the prevalence of left-handedness and left-hemispheric specialization in a population of people with impaired vision and hearing [5].
Neuroplasticity is a phenomenon unique to living organisms. Passive and active experiences correlate with changes in the structure and activity of the brain. It is induced by learning and environmental changes. Neural plasticity is the basis of higher neural functions, such as cognition, creativity and consciousness. Many aspects of neuroplasticity are ill-understood. Nevertheless, by comparing the progress of lateralization and plasticity in right- and left-handers in different species, a new model of asymmetry in brain function is proposed. This model clarifies the mutual influences of hemispheric specialization, gender, handedness, diseases, sleep, neurogenesis, memory, age, life expectancy, and the evolution of locomotion and language. As a consequence, it explains the role of several gene loci. It predicts that the evolution of language, cognition and creativity must be over late epochs in human evolution.
3.1. Hemispheric Specialization
The dominant model of the cerebral cortex at a broad level divides the human brain into two symmetrical hemispheres, Left and Right. It is known that the left and right hemispheres of the brain do not have the same discharges and sources. There was an early proposal to the effect that, as a general characteristic, the functions of the hemispheres were neutral. However, it has been found that the two hemispheres perform differently in their respective ways and that the dominant model is not entirely appropriate. Later, some scholars pointed out that handedness and directionality of asymmetries are domains where the left hemisphere is dominant. This is a wide model; for example, it includes the notion that a large proportion of the normal population (90% right-handers) is left hemisphere dominant for language. Some language-impaired right-handers are nevertheless left hemisphere verbal. So called “mixed-handedness” individuals have frequently been found not to show lateralization of language [2].
On the contrary, there are other scholars who regard the right hemisphere as the dominant hemisphere. The right hemisphere is upwardly associated with independence, wholism, divergence, glyphology, imagination visualization, creativity, freedom, perfectness, reliability, and dreaminess. A large number of studies have found that left-handedness and creativity are indeed related. For example, left-handed nonconformists gave quicker and more creative solutions to the Duncker candle problem. In visual convergence, left-handedness will be always better than right-handedness [6]. The dominant model of the cerebral cortex at a broad level divides the human brain into two symmetrical hemispheres,:1. Left, whose functions are more analytically.
3.2. Neuroplasticity
Neuroplasticity describes the brain’s ability to adapt and change through learning, experience, and injury. This adaptability is essential for cognitive plasticity, the capacity of an individual’s mental process to change. Neuroplasticity is of particular interest in left-handed individuals as this group has been seen with atypical neuroanatomical correlates and neurocognitive outcomes. These findings suggest a greater need for adaptability in these individuals.
Environmental factors have been seen to influence handedness expression; this may be the case in left-handed individuals. Atypical brain morphology may arise due to a more plastic pattern of neurodevelopment, perhaps in response to the environment. For instance, perinatal complications, like maternal stress, have been linked with an increased likelihood of left-handedness expression. Environmental experiences can have a lasting effect on cognition and brain functioning. An examination of neuroplasticity can provide insight into the left-handed population who may have been exposed to different neurocognitive patterns. Within the left-handed population, individuals may be more equipped to face novel challenges and as a result, may have increased cognitive abilities [2].
4. Creativity and Left-Handedness
Among the many questions of interest to those in the fields of psychiatry and psychology, that of cognitive style is of fundamental importance. An intriguing and oft-reported potential determinant of cognitive style is handedness. A concomitant with this question is that of creativity and its possible relationship to handedness. Handedness and creativity, interestingly and for reasons somewhat unclear, are the topics of much speculation and conjecture among scholars. Fluctuations in interest are sometimes correlated with the news cycle and social events. For example, the emergence and development of the dominance of the rock-and-roll subculture and its associated music culture in the 1960s and 1970s spurred much research on the musical and creative characteristics of left-handedness [2]. For the past few decades, and in particular since the start of the new millennium, the better intention than result has been the speculation on the mental imbalance associated with left-handedness. In general, left-handedness is posited to be associated with a greater variety in mental set and hence creativity by virtue of its less structured and thus more plastic cognitive styles. However, despite the overall interest and extensive literature, this question has been poorly addressed scientifically with forensic attempts and little promise of resolution [1]. The debated articles and reviews cover description and articulation of left-handedness and creativity and discuss the history and motivation underlying the hypotheses and relationships. On the other hand, there are perceptive theoretical frameworks and theoretical perspective on how and why left-handedness would be associated with creativity and underlying neurological, psychological, anatomical and genetic processes. Again, these afford attractive points of entry into a complex sociological and psychophysical issue susceptible to other types of investigations needing language other than that of purely scientific rationality.
4.1. Historical Perceptions
A stereotype that has persisted throughout history is the idea that left-handers are more creative than the right-handed [2]. Although to different degrees, there is a belief related to the creative ability of left-handedness across different societies. The belief about the creative ability of left-handedness is both philosophical and folk. India, Egypt, and Greece are places where philosophical discourse on left- and right-handedness have flourished. The Greek philosopher Aristotle holds the view that the left-handedness is treacherous, base and cowardly. Plato, on the other hand, emphasizes the contradiction of right and left. Nevertheless, the ancient mythical and philosophical traditions are not concerned with the creative abilities of left-handers. The Indian and early Egyptian civilizations add something to the Greek thoughts. In the early Islam empire, Al-Jahiz carried on the same discourse on left in his “Book of the Left-Handers”. At the late stage, the Greek philosophical thought on left-handedness was smoothly assimilated by the medieval Christian world.
4.2. Research Findings
Brain asymmetries are believed to underlie cognitive styles and may mediate creativity. While anatomical and functional brain asymmetries of left-handers (LHs) have been reported to differ from right-handers (RHs), these asymmetries have not been documented in terms of fluidity, originality, and elaboration in thinking tasks, as indices of divergent and convergent thinking, respectively. So far, there are no known studies that specifically analyze the relationship between the creative styles of LHs. To examine whether and how the creative styles of LHs in highly educated healthy adult individuals differ from creative styles in individual RHs in divergent and convergent thinking tasks. LHs exhibit greater left-brain lateralization than RHs in divergent thinking tasks and exhibit bilateral lateralization in convergent thinking tasks [2].
Therefore, the creative styles of LHs could be disclosed on brain activity in thinking tasks as greater right-brain lateralization of fluidity, greater left-brain lateralization of originality on the one hand, and greater bilateralization of thinking on elaboration on the other hand [1]. The lateralization of creativity in blank thinking tasks is in line with the activity of the default mode network and such network interactions could disentangle the creative styles of LHs and be detected on structural network connectivity by the structural correlate of creativity.
5. Conclusion and Future Directions
To conclude, after reviewing current literature on left-handers and their creativity, brain structure changes due to this handedness are suggested (mainly in the right hemispheric regions). Consideration of future research directions focusing on the role of left-handers in creative ability is warranted. Recently, it has been shown that nondominantly handed individuals (mainly left-handers) have better creativity and productive thinking ability in various tasks (i.e. designed by creativity indicators). Furthermore, right cortical brain regions (right insula and right DLPFC) were suggested to play a crucial role for creativity in the target task for nondominantly handed individuals, whereas the left insula, the left BA 10, and the left inferior occipital gyrus were highlighted for dominantly handed individuals. In light of the growing interest in the exploration of the origin of human creativity, this argument encourages creativity researchers to examine its brain origins from the perspective of handedness, with special attention given to left-handers [1].
References:
[1] F. Rahmani, H. Sanjari Moghaddam, and M. Hadi Aarabi, “Intact microstructure of the right corticostriatal pathway predicts creative ability in healthy adults,” 2020. ncbi.nlm.nih.gov
[2] T. Guadalupe, R. M. Willems, M. P. Zwiers, A. Arias Vasquez et al., “Differences in cerebral cortical anatomy of left- and right-handers,” 2014. ncbi.nlm.nih.gov
[3] D. Tomasi and N. D. Volkow, “Associations between handedness and brain functional connectivity patterns in children,” 2024. ncbi.nlm.nih.gov
[4] A. Wiberg, M. Ng, Y. Al Omran, F. Alfaro-Almagro et al., “Handedness, language areas and neuropsychiatric diseases: insights from brain imaging and genetics,” 2019. ncbi.nlm.nih.gov
[5] H. Wang, H. Zhou, Y. Guo, L. Gao et al., “Voxel-Wise Analysis of Structural and Functional MRI for Lateralization of Handedness in College Students,” 2021. ncbi.nlm.nih.gov
[6] J. Ren, F. Huang, C. Gao, J. Gott et al., “Functional lateralization of the medial temporal lobe in novel associative processing during creativity evaluation,” 2022. ncbi.nlm.nih.gov