Brain Lateralization

By James Harvey Stout (deceased). This material is now in the public domain. The complete collection of Mr. Stout's writing is now at >


Jump to the following topics:

  1. What is the theory of "brain lateralization?"
  2. The two halves ("hemispheres") are joined by the corpus collosum.
  3. We can specify the functions of the two hemispheres.
  4. Ideally, we develop "lateralization."
  5. We tend to use one half more than the other.
  6. We tend to distrust or even dislike the non-dominant half.
  7. We need to develop both hemispheres.

What is the theory of "brain lateralization?" Lateralization is the idea that the two halves of the brain's cerebral cortex -- left and right -- execute different functions. The lateralization theory -- developed by Nobel-prize-winners Roger Sperry and Robert Ornstein -- helps us to understand our behavior, our personality, our creativity, and our ability to use the proper mode of thinking when performing particular tasks. (The cerebral cortex is a part of the brain that exists only in humans and higher mammals, to manage our sophisticated intellect.)

The two halves ("hemispheres") are joined by the corpus collosum. This is a bundle of more than 200 million nerve fibers which transmit data from one hemisphere to the other so that the two halves can communicate. Although this nerve connection would seem to be vital, it is severed in a surgical procedure for some people who have epilepsy. The corpus collosum is up to 40 percent larger in women than it is in men.

We can specify the functions of the two hemispheres. (The following descriptions apply to right-handed people; for left-handed people, this information is reversed; for example, it is the right hemisphere which processes analytical thought.)

  1. The left hemisphere specializes in analytical thought. The left hemisphere deals with hard facts: abstractions, structure, discipline and rules, time sequences, mathematics, categorizing, logic and rationality and deductive reasoning, knowledge, details, definitions, planning and goals, words (written and spoken and heard), productivity and efficiency, science and technology, stability, extraversion, physical activity, and the right side of the body. The left hemisphere is emphasized in our educational system and in our society in general, for better or for worse; as Marshall McLuhan speculated, "The day when bureaucracy becomes right hemisphere will be utopia."
  2. The right hemisphere specializes in the "softer" aspects of life. This includes intuition, feelings and sensitivity, emotions, daydreaming and visualizing, creativity (including art and music), color, spatial awareness, first impressions, rhythm, spontaneity and impulsiveness, the physical senses, risk-taking, flexibility and variety, learning by experience, relationships, mysticism, play and sports, introversion, humor, motor skills, the left side of the body, and a holistic way of perception that recognizes patterns and similarities and then synthesizes those elements into new forms.

Ideally, we develop "lateralization." This is the use of the proper hemisphere for the task which we are doing. For example, when we are playing a friendly game of softball (a right-hemisphere activity), we would lose the essence of the game -- the fun -- if we were overly apprehensive regarding left-hemisphere matters such as rules and discipline. And when we are balancing our checkbook (a left-hemisphere activity), we don't want to be distracted by the right hemisphere's fascination with creativity and emotions. In every task, one hemisphere is dominant, but the other hemisphere participates to some extent; for example, we do have rules during the softball game, and we can feel happy when we notice that our bills are not as costly this month. When we understand lateralization, we become more efficient: we can consciously allow and emphasize the correct hemisphere, knowing that the sense-oriented right hemisphere is a better softball player, and the analytical left hemisphere is better in math. We also benefit from knowing which hemisphere to use during a particular stage of a task; for example, during problem-solving, we use the left hemisphere for the information-gathering stage, but we use the right-hemisphere during brainstorming and incubation of the ideas.

We tend to use one half more than the other. During childhood, we develop "brain dominance" -- the inclination to act and think in the mode of either the left or right hemisphere. The decision is affected by our genetics, childhood experiences, and family environment. The dominance is not total; whether we are "right-brained" or "left-brained," we permit the other hemisphere to lead occasionally.

We tend to distrust or even dislike the non-dominant half. If we generally use our left hemisphere, we might be annoyed by our right hemisphere as though it were an undisciplined child; contrarily, a right-hemisphere person might consider his or her left hemisphere to be a spoil-sport. These same attitudes might be projected onto other people. For example, if we favor the right hemisphere, but our co-workers are oriented toward their left hemisphere, we are likely to judge them as boring and rigid; if we favor the left hemisphere, we probably view our right-hemisphere co-workers as unreliable and disorganized. But both types of people can be effective if permitted to work in their own way, as some employers have discovered.

We need to develop both hemispheres. This is necessary because, as stated previously, some tasks require the left hemisphere primarily, and others predominantly call on the right hemisphere. Our brain dominance stays the same -- a right-hemisphere person does not change into a left-hemisphere person -- but we can develop the skills of the other half, so that that half will be more effective when we need to use it. We can enhance our non-dominant hemisphere in the following ways:

  1. First, we can become more aware of the two modes. What do we feel when we are in a right-hemisphere mode, and what do we feel when we are in a left-hemisphere mode? Refer to the lists of tasks that correspond to each hemisphere, and then note the various sensations throughout your mind and body while performing the tasks; while monitoring yourself, be certain that you are using the proper hemisphere (e.g., the right hemisphere while singing). We need to be able to sense the differences in order to ascertain whether we are indeed using our dominant or non-dominant hemisphere.
  2. We can become aware of the shift itself. To develop this perceptiveness, we can do an activity which predominantly calls for one hemisphere, and then switch to an activity which uses the other hemisphere, and pay attention to the feeling of transition in mind and body. When we know what the shift feels like, we can use this knowledge to verify that a shift has occurred on any occasion when we want to willfully change hemispheres.
  3. We can sense the requirement of each task as we perform it. We can change back-and-forth between hemispheres (by approaching the job playfully or analytically), to determine whether we feel better (and are more efficient) when we are in the right or left hemisphere during this task. For example, when we are housecleaning, we might think that that is a left-hemisphere task because we are attending to details and goals; however, because we are engaged in physical activity, the task is easier if we do it in the right-hemisphere mode -- relaxing and enjoying our body's movements and rhythms (and the aesthetics of a clean home). If we become more sensitive to the differences between the right- and left-hemisphere modes during our day's activities, we will become more aware of the needs of each task -- and we will probably be surprised by the number of tasks which are simpler and more delightful when we do them from the right hemisphere, with a sense of play, adventure, spontaneity, and creativity. Or, conversely, perhaps we will discover that some of our chores need to be switched from the right to the left hemisphere. If we do not yet have sensitivity regarding the appropriate use of hemispheres, we can make a logical estimation by asking ourselves, "How much analytical thought is required for this task?" In many cases, we are probably "thinking too much" about a chore that instead requires imagination and feeling.
  4. We can acknowledge the presence of the other hemisphere during any task. For example, while engaging the left hemisphere, we can be careful not to be too "serious" (and repressive of the right hemisphere); we may permit some creativity and delight while still accomplishing our goals. One way to involve the right hemisphere is to change our attitude from "I have to do this job now" to "I get to do this job now"; the statement invites the right hemisphere to cooperate and to find its little unobtrusive pleasures while we do our work. However, if the right hemisphere demands more attention than the task allows, we can simply promise to attend to it later; for example, "When I finish my work, I'll relax with a snack."
  5. We can make alterations in our lifestyle. For example, if our job keeps our left hemisphere engaged (particularly in an occupation such as accounting or computer repair), we can plan our free time and home life to utilize the right hemisphere. At work, we can try to schedule some times (however brief) to let the other hemisphere express itself; for instance, we can enjoy some personal conversations during our coffee break at work, instead of discussing business matters.
  6. We might become aware of the 90-minute cycles in which the brain tends toward one hemisphere and then the other. There is no practical way to schedule our lives around this cycle, but we might make some concessions to the fact that one 90-period will allow us a sharper intellect (from the left hemisphere), while the subsequent 90-minute period will grant us more creativity (from the right hemisphere). This cycle is probably identical to the 90-minute sleep cycle (i.e., the REM cycle); during sleep, the brain proceeds through a 90-minute cycle which is characterized by various levels of brain activity, with REM dreams commencing at the same point in each cycle.
  7. We can notice the frustration and exhaustion which occur when we use the improper hemisphere for a task; perhaps we habitually use the same hemisphere for virtually everything we do. For example, for some people, sex is a left-hemisphere activity because they are concerned with performance, goals (such as orgasms), size of body parts, and duration of time. The result can be impotence in the man, and frigidity in the woman. One approach in sex therapy is to teach the people to relax and enjoy, i.e., shift to the right hemisphere, which is the proper mode for sex.
  8. We can acknowledge other people's hemisphere-preference, to enhance our communication. After just a few minutes of conversation, we might be able to discern their preference by observing the following qualities in their speech. A right-hemisphere person tends to exhibit more feeling, emotion, visual imagery, humor, and a musical quality in the voice. A left-hemisphere person prefers logic, details, and a conversational structure that has an obvious direction and purpose. When we talk to either type of person, we can use the respective qualities so that we will be understood more easily. However, we need to give our listener a balance; many public speakers intentionally make frequent changes between the left and right hemisphere -- facts and emotions -- to keep the audience interested.