Loud & energized (E) / Quiet & calm (I)
Researchers discovered that there are biologically-based reasons for Extraversion and Introversion. Extraverts have a lower level of neuro-chemical stimulation in their brains while Introverts have a higher level. To help remain balanced, Extraverts release more dopamine in their brains and Introverts release more acetylcholine.
Dopamine is released when we seek external rewards, encouraging these actions with an immediate feeling of pleasure. Extraverts thrive on dopamine while it tends to overwhelm Introverts, making them feel anxious.
Acetylcholine is released in quiet moments and makes us feel mentally sharp, relaxed, and content. It enables us to think deeply, reflect, and focus on just one thing for a very long time. Introverts prefer this type of pleasure while Extraverts hardly notice it.
There is also a difference in our nervous systems. Extraverts tend to favor the side that activates the body’s fight-or-flight response. The brain becomes more alert and focused on its surroundings, the heart rate increases, muscles contract, pupils get larger, saliva decreases, bronchial tubes allow more air to the lungs, and adrenaline is released.
Introverts prefer the side of the nervous system that controls the body’s response while at rest. The brain withdraws from the outer environment and turns inward, the heart rate decreases, muscles relax, pupils get smaller, saliva increases, bronchial tubes allow less air to the lungs, and internal stability is maintained.
Evel Knievel was a soft-spoken man who let his daring stunts do the talking for him. Even after successfully jumping over 50 stacked cars at the Los Angeles Coliseum, the crowd seemed more excited than he did. He was happy at achieving his goal without injury, but his first words to the crowd and the man interviewing him were: “Well, another day, another dollar.”
After the government refused to allow him to jump over the Grand Canyon, Knievel quietly and calmly announced his plans for the next big jump: “I went to Idaho and I bought a piece of the Snake River Canyon. It’s my canyon. They cannot take it away from me and the only way they are going to stop me from jumping is with an antiaircraft gun. They are going to have to shoot me out of the air.”
In 2005, Tom Cruise appeared on The Oprah Winfrey Show. The frenzy of the women in the audience screaming while waiting for him was intense, but when he walked on stage their excitement grew to an uproar. While it is always nice to be welcomed and applauded, it might have been overwhelming for an Introvert. But it fed Tom’s need for dopamine, the chemical that Extraverts release that brings them an immediate feeling of pleasure. He enjoyed their cheering so much, just after he sat down he stood up again with a laugh as the volume rose to deafening levels.
Tom always had energy to spare, but he was exceptionally excited that day. When asked about his new love Tom could not contain himself, standing up and pumping his fists in triumph, raising one arm while pointing up, and then raising both arms while pointing up while he said, “That’s how I feel about her!” Then he dropped to one knee, pulled in his elbows for emphasis, quickly tapped on the floor with his right hand, and drew his elbow in again for another sign of victory before standing up. By this time, Oprah was screaming along with the audience, caught up in his contagious enthusiasm. When he sat back down, he finally answered Oprah’s question “What has happened to you?” using words: “I’m in love.”
He was so charged up, that in the sixteen minutes that followed he got up from Oprah’s couch twelve times. He dropped to one knee two more times while rapping the floor with his knuckles, raised both hands in victory once, took both of Oprah’s hands in his and playfully pushed and pulled against her three different times, and went from sitting to standing on her sofa in a quick leap two times.