©Arlene R. Taylor, PhD     www.ArleneTaylor.org

Trumpets are for extroverts.
—Lee Morgan

articles200408The voice over the wire—well, really not over a wire but by the miracle of Wi-Fi—sounded breathless, urgent, and pleading. “I’ve been assigned to make a 90-minute presentation on the differences between extroverts and introverts. Will you p-u-l-e-e-z-e help me? Everything seems really confusing.”

“If you are limiting your presentation to extroverted and introverted brains, it likely is confusing,” I replied. “They may account for only 30 percent of the population.”

A rather long pause followed. I waited.

The voice began again, “Who are the 70 percent?”

“Ambiverts,” I replied.

“Ambi-what?” floated back over Wi-Fi.

“Ambiverts,” I repeated. “Most people are.”

After some back and forth (the voice was a negotiator par excellence), I agreed to pull together some data from which “the voice” could create a speech.

For those of you who have noticed that some brains are very different from yours, read on, and have fun with the information.

The words extrovert, ambivert, and introvert refer to three general types of brains that tend to fall into recognizable categories on this planet. Some have described extroverts as brains estimated to be less alert when fully awake. They tend to seek higher than average levels of stimulation in the environment in order to feel alive and alert. This allows them to function in highly stimulating if not potentially dangerous situations that would be difficult if not impossible for other brains to handle.

Conversely, introverts are described as brains that are estimated to be highly alert when fully awake. They tends to gravitate toward environments that contain lower than average levels of stimulation in order to avoid becoming overwhelmed. Ambiverts have been described as brains that are moderately alert when fully awake and tend to function best with moderate levels of stimulation. Think of them as needing stimulation half the time and needing protection from too much stimulation half the time.

Hans Eysenck’s research led him to believe that the brains of human beings can be distributed along a metaphorical EAI continuum based on each one’s innate set-point of alertness (see below).



Estimated at 15-16% of the population

Outer directed seeking stimulation



Estimated at 70-72% of the population

Seek some stimulation and some relief from stimulation



Estimated at 15-16% of the population

Inner directed seeking relief from stimulation


Naturally it is possible to override a brain’s innate set-point based on what is happening in a given environment and depending on what it perceives is necessary or required of it. Studies have shown that most brains can do this periodically for short periods of time with a minimum of negative consequences. Spending long periods of time in environments that do not match your brain’s innate set-point, however, tends to cost you in additional energy expenditures. This impacts not only your level of available energy but also the amount of time required to recharge your brain’s batteries, and eventually can have a negative impact on your health, relationships, career, and overall success in life.

Based on your innate set-point you will likely feel most comfortable, productive, and utilize your energy most efficiently in one of three types of environments:

  • An extroverted environment that offers higher than average levels of stimulation in order to feel alive and alert.
  • An ambiverted environment that offers moderate amounts of stimulation in balance.
  • An introverted environment that contains low levels of stimulation, thereby providing protection from over-stimulation.

Socrates preached “Know yourself!” This has likely always been key to success but may now be easier than ever before—because in this, the age of the brain, scanning equipment and other modalities have provided information that can make this task of identification much easier to do.

Stereotyping Disservice

Extroverts, ambiverts, and introverts tend to exhibit different preferences and characteristics. Unfortunately, there has been a great deal of stereotyping, especially of the extremes on the EAI Continuum. This stereotyping is often inaccurate and no doubt has done a disservice to everyone.

WhereAreU clip image003Extroverts have often been referred to as loud, noisy, and in-the-middle-of-everything party people. They have also been accused of being rude and unfeeling, exhibiting bull-in-a-china-closet behaviors, and exhausting to be around.

Introverts, on the other hand, have been labeled as wallflowers, stick-in-the-mud people, or excessively shy. They have been accused of being stuck up, wearing their feelings on their elbows, exhibiting better-than-thou behaviors, and unfriendly.

Attempts have often been made to shove ambiverted brains into one of these two categories, and it has only been fairly recently that researchers have realized that the majority of people are actually in a more moderate category. Many people have never even heard of the term ambiversion. Indeed, less is known about it. Currently it appears that the ambiverted brain functions best in a moderately stimulating environment, requiring moderate levels of stimulation and almost equal amounts of relief from it. Rather than continually repeat this, concentrate on recognizing the differences between extroverts and introverts, and know that at this stage of the research, ambiverts will exhibit milder forms of characteristics with a few exceptions.

Note that the way in which brains prefer to obtain needed stimulation has little if anything to do with whether or not they like people—and much more about the type of environment that works for each type of brain. An extrovert and an introvert may both like people equally well (or not). Given the choice, however, each will usually gravitate toward very different types of environments. Some extroverts may prefer to hang out with other human beings because it’s a quick way to obtain the stimulation their brains crave in order to thrive. Others may prefer to obtain needed stimulation by engaging in activities that involve nature or machines or travel, choosing to avoid interacting with other humans whenever possible.

Some introverted brains may dearly love to connect with people, but discover they are able to do so only for short periods of time or with one or two persons at a time. They may enjoy travel, but they may go alone or with a few close friends, avoiding large groups or noisy tours. Others prefer to read and study in a quiet library- or research-type setting.

It’s not good or bad, desirable or undesirable. It is what it is, and the brains that figure out the type of environments in which they function best, have a definite advantage over those that do not. They can manage their brains by design, knowing when to obtain higher or lower amounts of stimulation, and how long to remain in specific environments. It they don’t have the option of choice, at least they understand reasons for their feeling sleepy and bored, or wired and exhausted.

Key Characteristics

Following are ten characteristics that tend to exhibit themselves quite differently in extroverted versus introverted brains.

1. Blood Flow Levels

Brain imaging studies have been able to track blood flow levels to the brain and have come to some interesting conclusions in relation to the extremes of extroversion and introversion.

Extroverted brains tend to have lower rates of blood flow which translates to lower internal stimulation and less than average levels of alertness. Consequently they crave stimulation to remain awake and alert. Shorter, fast-acting, and less complicated blood flow patterns involve brain areas related to sensory processing, except for smell (according to PET scan studies by Dr. Debra Johnson). The dominant pathway is activated by dopamine, the feel-better chemical.

Introverted brains have higher than average blood flow rates to the brain suggesting higher rates of internal stimulation and higher than average internal levels of alertness. Therefore they do not need large amounts of stimulation to stay alert and pay attention and tend to function best in environments with low amounts of stimulation. In fact, think of them as being so wide awake that they require protection from overstimulation. Long and complex blood flow patterns involve brain areas involved with internal experiences (e.g., planning, problem solving, remembering).

2.  Special Giftedness

The extremes of extroversion and introversion possess a form of innate giftedness (each is different) that is not seen in the ambiverted brain.

The extroverted brain has a metaphorical callus that allows it to function in situations that would be difficult (if not overwhelming and impossible) for more introverted brains. It helpsprotect them from being readily hurt or bested in highly stimulating, competitive, or combative situations (much as real calluses protect the fingers of string players so they can play without pain.). They are often able to perform better under pressure (e.g., exams, conflict, negotiations, and performance situations). Extroverted brains tend to be less responsive to punishment. They are likely to continue acting in the face of frustration and may take longer to form conditioned reflexes. Because of their constant search for stimulation and variety, they are at higher risk for getting in trouble (e.g., delinquency) although this may have been unintended.

WhereAreU clip image005Introverted brains possess a special ability to block additional sensory input to allow processing of what has been absorbed already. They have no protective callus, therefore, they may struggle to perform in situations of pressure (e.g., exams, conflict, competition, and public performance). If the pressure is great enough, they may even shut down to some degree. If, on the other hand, they choose to perceive performances as one-to-one situations, they may handle the actual performance very well. The problem arises when they are expected to socialize before or after performances or group events. When required to spend large amounts of time functioning in environments that do not match their introverted position on the EAI Continuum, they may crash or become ill. Introverted brains tend to form conditioned reflexes more easily. This means they may be easier to train and be more sensitive to both punishment and negativity.

3. Modification of Data

The thalamus, located just above the brain stem, “triages” sensory data as it enters the brain. When all functions are working properly, the thalamus will route the data to the correct decoding sites. During this process the Reticular Activating System (RAS) in the brain stem modifies the amount of amplification or reduction in intensity of incoming sensory stimuli¾for some brains.

In extroverted brains, the RAS miniaturizes the volume and intensity of incoming sensory stimuli. Think of those brains as manipulating miniature objects in a table-top exercise. Because everything is reduced, extroverted brains not only can handle larger amounts of incoming sensory stimuli, but crave significant levels of stimulation.

WhereAreU clip image007In introverted brains, the RAS amplifies and magnifies the volume and intensity of incoming sensory data. This ups the ante. Everything is perceived as larger than life. Sounds are louder, colors are brighter, and motions are larger. Think of introverted brains as trying to cope with loud, colorful, giant, moving everything, as in the fable of Babe and the Big Blue Ox. As a consequence, introverted brains can become overloaded quickly and require protection from stimulation. In most urban environments the sounds of life and living are everywhere. They can be overwhelming to an introvert, as everything becomes magnified in the brain. Thus, introverts are more likely to wear earplugs to reduce the intensity of the sound. In fact, earplugs may be a necessity for the average introvert just to survive in everyday living environments.

In The Roots of the Self, Dr. Ornstein described this phenomenon rather elegantly. The average brain-stem setting for the input system differs in each brain. The amount of amplification influences everything. Some, with low amplification in their nervous system, are starved for stimulation all the time. Others, with very high amplification, are surfeited. The remainder are somewhere in the middle.

4. General Focus

Some of the behavioral differences between extroverts and introverts likely result from using different brain pathways that influence where the individual directs his/her focus—internally or externally.

Extroverted brains tend to be outer-directed. They constantly interact with the environment to obtain the stimulation the brain craves in order to feel alive/alert. They generally prefer less depth and a wide (often intense) variety of experiences. Because of a desire for variety, they can become quickly bored with routine. They often like to be in the middle of whatever is going on, even when they may not be sure exactly what is going on, being confident they can figure it out as it goes; fly by the seat of their pants, so to speak. All they need is to be selected and allowed to participate. Being more outer-directed, extreme extroverts may experience lower levels of anxiety prior to or during testing or competitive situations.

WhereAreU clip image009Introverted brains tend to have an internal focus and are more inner-directed. They can retreat inwardlyalmost automaticallyto evaluate, ponder, and reflecton data to gain new understanding. They tend to prefer more depth (pondering) over variety so they may be very selective and even limit the experiences with which they become involved. Unlike during periods of the middle ages when introverts were rewarded (e.g., allowed to enter religious orders where they were protected from the outside world and taught to read, and write, and illustrate manuscripts), introverted brains are not particularly rewarded in current society. Consequently, introverts may be at higher risk for depression. They may experience higher levels of anxiety prior to and/or during a testing situation. Surprisingly, they may handle public presentations more easily, especially if they perceive it is a 1-1 situation: one person and one audience.

5. Energy Recharging

In life you usually give up something to get something. Taken to its bottom line, the basic medium of exchange in life is energy. Not money, talent, or time. Energy. All you are is energy. As the authors of The Power of Full Engagement put it:

Energy is the fundamental currency of high performance . . . managing energy, not time, is the key to high performance and personal reward.

Extroverted brains tend to become energized by interacting with their outer world. While they are not necessarily loud and continually active (although that is the stereotype) they tend to expend energy freely and refresh themselves by doing something in their outer world. Their energy can be drained in an environment that is lacking in stimulation, which is one reason they usually like to be where the action is. Where the action is may be interpreted very differently by each brain, however. This may involve playing challenging video games on a computer, white rafting on category-five rapids, jumping out of airplanes, extreme sports, or involvement in competitive events and situations. At the end of the day or an event these individuals may still be looking for one more activity before they call it quits. In their search for variety and stimulation they may have difficulty setting aside appropriate amounts of time to relax, reflect, and give their brains and bodies the rest needed for rejuvenation.

WhereAreU clip image011Introverted brains are energized primarily by interactions with their inner world. Their energy can be drained in large groups of people, where there are high levels of noise, in highly stimulating or competitive environments, or where there are frequent interruptions or distractions. They need to pay attention to the amount of energy a specific activity will require because it can take longer for their energy to be restored, for their internal batteries to be recharged. They may have enjoyed a specific event very much but are likely to heave a sigh a relief and be glad it is over. They can handle complexity unless it is required in too many arenas simultaneously. Introverted brains may choose solo performances. If they do participate in groups, they likely won’t be the first to arrive and the last to leave. They are more likely to arrive, do the performance, and then withdraw to a less stimulating environment. Don’t count on them to attend all the ancillary parties and receptions. If need be, they will put in a token appearance and then leave.

6. Accruing Experiences

In general, the human brain likes variety and wants to pursue new experiences. Most brains also tend to experience times when it is completely normal to be a bit shy about a new situation, environment, or experience. There are some differences among the three types of brains in terms of approach to accruing experiences, however.

WhereAreU clip image013For the extroverted brain, life is about collecting experiences. Think of these brains as possessing a huge radar screen for accruing experiences. They usually prefer a great deal of variety with differing types of stimuli. Generally the more intense the experience the better they like it. They often have a large circle of friends but may experience less intimacy in their relationships.

Introverted brains, that already have a high level of internal stimulation, tend to pursue experiences at a much less frenetic level. They prefer less variety and typically want to learn more about fewer experiences, in depth. Life is more about pondering the experiences they do have than accruing more just for sake of stimulation or variety. Friendships sometimes follow this pattern, as well. Introverts may have fewer close friends but may experience more depth in their relationships.

7. Pathway Fuel

Every brain needs fuel. Typical brain fuels involve oxygen, glucose, and micronutritional factors. In terms of brain function, studies have shown that specific neurotransmitters (brain chemicals) appear to be associated with at least the extroverted and introverted brains.
WhereAreU clip image015
The dominant pathway in extroverted brains is activated by dopamine. It should come as no surprise, therefore, that extremely extroverted brains may be at risk for becoming involved with substances (e.g., cocaine and amphetamines) or activities (e.g., gambling, high-risk activities) that increase dopamine levels.

The dominant pathway in introverted brains is activated by acetylcholine, a brain chemical that helps a person focus. Consequently, introverts tend to find it easier to focus and to pay attention to something for longer periods of time.

8. Absorption of Data

WhereAreU clip image017Picture each type of brain as having a metaphorical opening with an optimum diameter, although the aperture can dilate or constrict depending on the environmental circumstances. Think of it as a Goldilocks-and-The-Three-Bears story: large opening, moderate opening, or a small opening. Think of extroverted brains as having a relatively small aperture that takes in less data second for second. Consequently it is continually searching for the stimulation it requires (e.g., metaphorically, it takes pictures as quickly as possible to obtain sufficient stimulation. A small diameter aperture allows it to zoom in, narrowly focus, and be less easily distracted by surroundings when focused on a task or activity. The extroverted brain tends to have greater activation in the limbic system (e.g., the emotional recognition system is highly active and is triggered by a wider range of people). If they receive insufficient stimulation, they may become quickly bored and even fall asleep. This can happen almost automatically if not enough is going on in the environment to keep them awake and alert.

WhereAreU clip image019Think of introverted brains as having a large aperture that allows them to absorb huge amounts of data second for second. Metaphorically, this allows the brain to become overwhelmed quickly. It can also easily become distracted by its surroundings. They usually need protection from overstimulation to avoid becoming overwhelmed. When overstimulated after being flooded with data, the screen of the introverted brain may temporarily go dark (metaphorically) to give it a break. It needs time to process information from one “wide-angle picture” before snapping another. The introverted brain tends to have lower levels of activation in the limbic system (e.g., the emotional recognition system is underactive and face-to-face conversations may be only as engaging as the content of the conversation). Introverted brains may gravitate toward smaller practice or performance groups or lean toward solo practice and performance in order to better manage the level of stimulation.

9. Norepinephrine

As a neurotransmitter, norepinephrine (noradrenaline) is concentrated in a group of neurons in the brain stem, part of the reptilian layer. This substance influences one’s level of alertness, excitement, attention, dreaming, sleep, and mood. As a hormone, norepinephrine is synthesized by the adrenal medulla and is implicated in resisting stress.

WhereAreU clip image021Extroversion is associated with low levels of norepinephrine. This means that extroverted brains often perform well under stress and enjoy, if not actually thrive, on competition. The win-lose scenario offers a higher level of stimulation that helps feed the brain’s desire for variety and stimulation. If extroverted brains love music, they may use a Walkman to liven up any dull (read that unstimulating) situation. Some might view this behavior as antisocial or as downright rude. Those are possibilities, of course. More likely, those brains are craving immediately stimulation and it’s a fast way to get it.

Introversion is associated with high levels of norepinephrine. Introverted brains tend to perform less well under stress and prefer to avoid competition (with anyone but the self) if at all possible and at all cost.

Since levels of norepinephrine increase during stress, the brain may experience an artificial push toward the introverted end of the continuum if it experiences large amounts of stress or chronic anxiety for a minimum of two years or more. Chronic anxiety can be caused by any number of situations (e.g., abuse, catastrophic events, chronic illness, unresolved grief, extreme pressure to perform especially outside one’s comfort zone). It’s as if the brain says to itself, “The way in which I am being asked to function is not working for me. I will try to take care of myself temporarily by activating a state of protective alertness (introversion). With resolution of the stress/chronic anxiety, the artificial level of protective alertness can resolve.

10. Working on Teams

Perhaps more than you might think, your comfort in teamwork situations is impacted by your innate position on the EAI Continuum.

Extroverts: Tend to be independent workers, star performers, experts, and deal makers. They may agree to work on a team for short-term projects but dislike long-term team projects.

Introverts: Tend to be independent workers, researchers, and writers. They prefer to submit their reports in writing rather than attending in person.

Ambiverts are more likely to enjoy teams and teamwork. Some may like to function as the chair while others may prefer to be a resource specialist and provide reports as their contribution.

Know Who You Are

The difficulty comes when individuals don’t know their own style or think their style is the norm and there’s something wrong with other brains that are unlike theirs. For example, notice the differences in perception by the following two authors. The first statement shows an extroverted perspective, while the second reflects introversion.

People who make no noise are dangerous.                             —J. de LaFontaine, Fable, 1678

Noise is the most impertinent of all forms of interruptions.                 —A. Schopnhauer, 1852

Is there a best or more desirable position on the EAI Continuum? Probably not. This world needs all types of giftedness for differing reasons. Based on your innate position, however, there will be activities and functions that your brain will do more easily and energy-efficiently. Identify those and work to maximize your strengths.

Your position on the EAI Continuum can have a major impact on any and every aspect of your life. When you are required to function in situations and environments that are not optimum for your type of brain function, learn how to work within them in a way that protects your brain and minimizes negative consequences. You will be glad you did. That will allow you to use your brain by design to be more successful.

(A free Extroversion-Ambiversion-Introversion Assessment is available at https://arlenetaylor.org/assessments)