Creativity and Left Hand Preference

Creativity is heavily dependent on novelty, and in the chapter on intelligence (chapter 2) I wrote about the importance of divergent thinking in creativity. I also discuss divergent thinking in the chapter on the frontal lobes (chapter 9). Coren (1995) studied the relationship between handedness and divergent thinking and found that left-handed people are better at divergent thinking than are right-handed people. The reason for this left handed superiority for divergent thinking is not known. When presented with a problem, however, divergent thinking might depend on the ability to recruit networks that have a substantially different architecture than those usually recruited in response to this problem. This allows a person to escape the constraints of existing internal models, represented in the networks usually used for thinking in a particular domain. Hence, creativity might require the ability to make associations between a variety of different concepts and representations, and, as mentioned, the cortex in the right and left hemispheres, which are connected by the corpus callosum, store very different types of representations.

The corpus callosum mediates communication between the hemispheres, and interhemispheric communication might play a vital role in creative endeavors. Support of this postulate comes from the observation that there is a reduction of creativity associated with damage to the corpus callosum. Witelson (1985) reported that the corpus callo-sum is larger in left-handed people than in right-handed people, and she suggested that the greater use of bihemispheric cognitive representations in left-handed people might be related to the greater anatomical connection between the two hemispheres. Thus, in people who are left handed, the increased ability of the hemispheres to communicate might provide a greater ability to recruit and associate diverse networks that store different forms of information, a process that might be very important in the creative process: seeing the thread that unites.

In the chapter on neurotransmitters (chapter 8), I describe the relationship between creativity and mood disorders, such as depression. In many creative domains there is a high prevalence of people who have mood disorders. Several studies have also examined the relationship between hand preference and depression. These studies found that the prevalence of depression is higher in people who are left handed than people who are right handed. For example, Elias, Saucier, and Guylee (2001) administered a depression inventory to a large group of college students and found that left-handed men were much more likely to have suffered with depression, but the reason for the association between left-hand preference and depression is not known.

To better understand the relationship between hand preference and creativity, we might find it worthwhile to examine several different domains of creativity. In the following sections I discuss some creative domains.

Musicians

Hassler and Gupta (1993) studied 51 young adult musicians and non-musicians. These participants were tested with Wing's Standardized Tests of Musical Intelligence and a handedness questionnaire. These investigators did find that musical talent was related to left-handedness. In another study, however, Hering, Catarci, and Steiner (1995) investigated professional musicians who were playing in orchestras, and they did not find a higher incidence of left-handedness in these orchestras than found in the general population. In a third study of handedness and musical ability, Jancke, Schlaug, and Steinmetz (1997) examined asymmetries of hand skills on two handedness tasks in consistent right-handed musicians and nonmusicians. These right-handed musicians revealed a lesser degree of hand-skill asymmetry than consistent right-handed nonmusicians, and it was this increase of left-hand skills in musicians that accounted for their reduced asymmetry. These results suggest that even right-handed musicians might be more ambidextrous than nonmusicians. Practicing skilled movements, however, not only can enhance motor performance but can even alter the portions of the brain that mediate these skills. For example, Nudo and his coworkers (1996) trained monkeys to perform skilled motor tasks and noted that the brain areas that control the finger of the hand that learned this task enlarged. Thus it remains unclear if this increased tendency of musicians to be ambidextrous is related to their genetic endowment or if accomplished musicians practice long hours to increase the skill of both hands and this practice alters their motor asymmetry.

Although practice can enhance motor skills, in most hand-preference inventories right-handed people appear to be more biased toward using their preferred right hand than are people who prefer their left hand. Hence, in general left-handed people tend to be more ambidextrous. Playing most musical instruments requires the coordinated use of both hands, and this might give left-handed people an advantage. Christman (1993) noted that although playing some instruments requires temporal integration (e.g., the string instruments), playing other instruments requires independent bimanual motor activity (e.g., the keyboard instruments), and people who had mixed handedness (e.g., ambidextrous) are superior at playing the instruments that require independent bimanual activity.

Schlaug, Jancke, Huang, and Steinmetz (1995); Lee, Chen, and Schlaug (2003); and Ozturk, Tascioglu, Aktekin, Kurtoglu, and Erden (2002) found that musicians had larger corpus callosums than matched control participants. These investigators posited that it was nurture rather than nature that determined these differences, suggesting that the early commencement and continual practice of bimanual training is the "external trigger" that induced this callosal enlargement. As I mentioned earlier, Nudo et al. (1996) demonstrated that functional specialization can be altered with practice and Rosenzweig (1972) demonstrated that animals placed in enriched environments had larger heads than those who were not placed in these environments. To my knowledge, however, there is no direct evidence that practice can alter the size of the corpus callosum. Although talented musicians can be creative in their interpretations, it is primarily the people who write and compose music who are the most creative in this domain. I searched the literature, but unfortunately, I could find no studies that assessed composers' handedness or examined their brains.

Visual Artists

In the introduction of this chapter, I mentioned that some of the greatest artists were left handed. When I searched the literature for systematic studies of visual artists (painters, sculptors, etc.), I could not find many systematic studies of handedness in this group. In one of the few studies I found, Peterson (1979) investigated hand preference in art students and found in this group of art students there was a higher percentage of people who preferred their left hand than there is in the general population. In contrast, in one of the few studies that attempted to learn the hand preference of great painters and to find out what proportion were left handed, Lanthony (1995) studied the portraits of the painters but found that self-portraits were worthless because painters often paint themselves by viewing a mirror image. Thus, an investigator who was attempting to learn if the artist was left or right handed by examining self-portraits could not tell if the artist painted what he or she saw in the mirror (that would have right-left reversed the hand holding the brush) or if he or she corrected for the mirror image. To avoid this confound, Lanthony only studied portraits of painters made by another painter or by photography. Right-handed artists make hatchings (e.g., for shadows) that descend from right to left, and left-handed artists make hatchings that descend from left to right. Thus, Lanthony also studied artists' hatchings. Finally, Lanthony examined the literature that was available about famous artists. Using these methods Lanthony was able to include in this study 500 painters. These painters were divided into two groups: 127 painters studied by portraits and hatchings, and a population of 373 painters studied by hatchings only. In the first population, the proportion of left-handed painters was 4.7%. In the second population, the proportion of left-handed painters was 2.1%.

In the general population, the prevalence of left-handedness is about 7% to 10%. Thus, according to Lanthony's study, left-handed people are underrepresented in a population of highly creative painters. Prospective studies that assess the handedness of painters, however, need to be performed.

We do not know why there is a higher proportion of creative visual artists who are right handed. As I mentioned, studies of brain-damaged people have revealed that damage to the right hemisphere impairs visual-spatial, visual-perceptual, and visual-constructive processes (see Benton & Tranel, 1993, for a review). For example, in a face-matching test, participants are asked to determine if two faces are the same or different. In this test the photographs of the two faces are taken at different angles such that the participant cannot determine if the two pictures are the same or different people by making point-to-point comparisons, but instead, the subject must develop an object-centered or face-centered perceptual representation. Patients with right-hemisphere injury are often impaired on this face-matching test. Patients with right-hemisphere disease are also impaired in a test where they are shown a series of cards with two line segments and are asked to study and recall the relationship (angle) between these two segments.

Patients with either left- or right-hemisphere injury, such as stroke, have problems with drawing and copying drawings, but they make different types of mistakes. Whereas the patients with left-hemisphere disease have problems with planning the drawing, those with right-hemisphere disease cannot accurately represent the spatial relationships between the elements in the drawing. By virtue of using their left hand, visual artists might have more direct access to the hemisphere that is dominant for visual-spatial and visual-perceptual processing, which might give left-handed people an advantage, but this postulate is not in accord with Lanthony's (1995) results.

The hypothesis that the right hemisphere can better mediate the visual-spatial processes that are important in drawing and painting also draws support from studies of patients who have undergone section of the corpus callosum for the control of epilepsy. This procedure disconnects the right and left hemispheres. When patients who have had this procedure are asked to copy or draw pictures with their left hand, which has access primarily to the right hemisphere, they performed much better than when they attempt the same drawing with their right hand. This finding is also inconsistent with Lan-thony's (1995) results.

People who teach visual arts attempt to capitalize on this hemispheric dichotomy. For example, Betty Edwards (1999), who wrote Drawing on the Right Side of the Brain, claimed that her book is one of the first practical applications of the information reported by Sperry and his colleagues, who demonstrated using the split-brain (callosal disconnection) paradigm that the two hemispheres had different processing strategies and that the right hemisphere had superior spatial abilities. In this book, however, Edwards does not suggest that right-handed people use their left hand to draw and paint as some people have suggested, but she does attempt to teach people the means by which they might activate and predominately use the right-hemisphere processing strategies.

Although when using the left hand, they might have greater access to the right hemisphere that mediates visuospatial skills, left-handed people often have a different brain organization than do people who prefer their right hand. As mentioned, 70% of left-handed people have their language mediated by the left hemisphere, the other 30% can either mediate language with both hemispheres or mediate language with the right hemisphere. Masure and Benton (1983) assessed visu-ospatial judgment in a population of left- and right-handed people who had injuries of either their left or their right hemisphere. In the right-handed patients, impaired performance on visuospatial tests were found to be almost exclusively associated with right-hemisphere injury. In Masure and Benton's study, the left-handed patients showed the same performance pattern as the right-handed patients. They found that a high proportion of left- and right-handed patients with right-hemisphere lesions performed abnormally, whereas all the patients with left-hemisphere lesions performed normally. On the basis of these results, Masure and Benton concluded that the hemispheric cerebral organization of visuospatial functions do not differ between left- and right-handers. Hence, if there are differences in artist ability between left- and right-handed people, this difference cannot be related to the hemispheric mediation or organization of visuospatial skills.

The left hand, might also have direct access to other representations that are important in artistic production. One of the most important skills that creative artists need is the ability to portray emotions. There are many means by which emotion can be portrayed, but perhaps one of the most common is in the painting of faces. About 30 years ago in our laboratories, We (DeKosky, Heilman, Bowers, and Valenstein, 1980) studied patients with strokes that were limited to either the left or right hemisphere by showing them pictures of emotional faces and asking the patients to name the emotion expressed by the face, or by having the patients point to a face from a series of faces that expressed an emotion named by the examiner. These patients were also asked to tell them if two faces were expressing the same or different emotions. We found that when compared with normal controls and patients with left-hemisphere strokes, the patients with right-hemisphere strokes were impaired at discriminating emotional faces. Because the right hemisphere might be dominant in processing faces (Benton & Tranel, 1993), it is possible that the findings reported by DeKosky et al. were related to a deficit in facial recognition rather than a deficit in the recognition of emotional faces. Subsequent studies not only replicated the DeKosky et al.'s study but also revealed that the deficit in emotional-facial recognition induced by right-hemisphere injury could not be entirely accounted for by a visuospatial defect or a deficit in face processing (Bowers et al., 1985).

Imagery is very important in the creative process and visual imagery is a very important skill for creative visual artists. In chapter 4 I discussed imagery and mentioned the study of Bowers, Blonder, Feinberg, and Heilmann (1991), who studied object versus emotional-facial imagery, and demonstrated that patients with right-hemisphere lesions are impaired at imaging emotional faces but not objects and patients with left-hemisphere lesions are impaired in object but not emotional-facial imagery. Thus, it appear that the right hemisphere contains representations of emotional faces and the left hand might have better access to these representations.

Studies of patients with right- and left-hemisphere lesions have demonstrated that the right hemisphere also appears to be critical for the expression of emotions under natural conditions (Blonder, Bowers, & Heilman, 1991). In concert with Blonder et al.'s findings, Sackeim, Gur, and Saucy (1978) took pictures of normal people who portrayed emotional facial expressions, cut them in half, and created whole faces from the left and right half faces. They showed normal people these composite left and right faces that were expressing emotions and asked these people to judge or rate the intensity of emotion expressed by these composite faces. Sackeim and coworkers found that the composite picture made from the left-side components expressed emotions more strongly than did the composite made from right-side components.

Schirillo (2000) reported that portrait artists have predominantly painted portraits with the model's left cheek facing the viewer. These painters do this even more when women are the models (approximately 68%) than when men are the models (approximately 56%). Schirillo also noted that many of the portraits painted by Rembrandt typify this asymmetry. The reason that artists paint portraits in this manner is not known, and it is also unclear how this asymmetry might be related to handedness, but the finding that the left side of the face is more emotionally expressive might account for why the artists have their models pose in this position.

The visual system is crossed such that when a normal person looks straight ahead and a visual image is shown on the left half of their visual field, this image projects to the right hemisphere. If the image is flashed to the right side it projects to the left hemisphere. When words are flashed to the left versus right visual field, people detect the words better when they are seen on the right than left because the left hemisphere is dominant for language. In contrast, when pictures of faces are flashed to the right or left visual field, normal people see them better when they are flashed to the left than to the right visual field. When the task was to recognize emotional facial expressions, the left-visual-field-right-hemisphere asymmetry was even stronger than detecting nonemotional faces. These studies in normal people provide converging evidence that the right hemisphere is dominant not only in the processing of faces but also in the processing of facial emotions. If emotional faces are seen better in the left than in the right visual field, but the left face is more expressive than the right, when a model directly faces the artist the part of the model's face that best expresses emotions will be observed by the artist's right visual field. This right visual field projects to the left (verbal) hemisphere, which is less proficient at perceiving emotions and performing visuospatial processing. Although the great artists might not have known about these hemispheric asymmetries, they might have had implicit knowledge about these asymmetries of facial expression, and this knowledge might be the reason they had the models turned so that the model's left side of their face would be seen by both sides of the brain.

The use of the left hand to paint or draw might allow direct access or selective activation of the right hemisphere, which is dominant for mediating visuospatial skills, storing the representations of emotional expressions, and performing global processing. All these functions are important for artistic skills, but creativity and artistic skills are not always directly linked. There are many extremely talented painters who are able to accurately represent a face or a scene; however, these artists might not be creative and instead be primarily craftsmen or craftswomen.

Authors-Writers

As I mentioned earlier, since the classic work of Paul Broca it has been known that the left hemisphere is dominant for mediating language. This does not mean, however, that the right hemisphere plays no role in creative verbal communication. Skilled authors often use metaphor and connotative as well as alternative word meanings. Brownell, Simpson, Bihrle, Potter, and Gardner (1990) studied patients with right- and left-hemisphere lesions by using a sorting task in which participants responded on the basis of the alternative meanings of words (adjectives and nouns) that have more than one meaning (polysemous). Warm, for example, means having a higher than median temperature but also means loving and affectionate. They found that in spite of having aphasia, the patients with left-hemisphere damage were better at detecting metaphoric meaning than were non-aphasic patients with right-hemisphere damage. On the basis of these results, these authors concluded that in normal people the right hemisphere is dominant for mediating metaphor. In another study Brownell et al. (1986) presented pairs of sentences and had the participant make inferences about the meaning of these two sentences. They demonstrated that compared with those patients with left-hemisphere damage, the patients with right-hemisphere damage were impaired at making inferences. Kaplan, Brownell, Jacobs, and Gardner (1990) studied the ability of right-handed patients who had either left- or right-hemisphere damage to understand the nonliteral interpretation of conversations and found that patients with right-hemisphere damage were more impaired than patients with left-hemisphere damage. The comprehension of nonliteral utterances is important in understanding a character's intentions and his or her internal states.

In creative writing the ability to use techniques such as metaphor and inference is critical, but so is the overall organization of sentences and paragraphs. Delis, Waper, Gardner, and Moses's (1983) study of patients with right- and left-hemisphere damage showed that the patients with right-hemisphere damage were also impaired at organization. In regard to content, creative writers often portray emotional states and write humorous works. Bihrle, Brownell, Powelson, and Gardner (1986) studied the ability of patients with right- and left-hemisphere strokes to comprehend humor by showing them cartoons, and they found that patients with right-hemisphere disease were impaired at detecting humorous cartoons. There are multiple forms of humor, and the role that each hemisphere plays in processing humor still needs to be investigated.

On the basis of this brief review, we can see that creative writing requires the use of both hemispheres. Thus, writing with one hand versus the other would not confer any benefit. In addition, now many writers use keyboards where both hands are used. Because creative writing would require the use of both hemispheres, perhaps people who have better interhemispheric communication by means of the corpus callosum would be more creative. Earlier in this chapter, I mentioned that people who prefer their left hand might have thicker corpus callosums, and if bigger is better, a thicker callosum might allow better interhemispheric communication. If this were the case, then we would expect a higher proportion of left-handed versus right-handed people to be creative writers. I searched the literature to see if there were more creative writers who were left handed, but I could find no studies either to support or to refute this postulate. The only systematic study I could find was by Halpern, Haviland, and Killian (1998), who examined the relationship between handedness and the portions of the Medical College Admission Test that assess verbal reasoning. These investigators found that left-handed people who took this test obtained higher scores on the verbal reasoning test than did right-handed people, but right-handed people scored higher, on average, on writing. Overall, one always has to be cautious about making positive statements in the absence of scientific evidence, but I suspect if a high proportion of writers preferred their left hand, this relationship would have been reported. Thus, like visual artists such as painters, the prevalence of left-handed creative writers is probably no higher than the prevalence of left-handedness in the general population.

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  • DANAIT
    Are left handed people more creative then right handed people?
    10 months ago

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