Tom Falkenstein - The Highly Sensitive Man

Sensitivity, Introversion, and Extroversion

We are all different, and we arrive in the world with some of these differences. Anyone who has kids or who has friends and family with kids knows that newborn babies already differ from each other, even in their very first few weeks of life. Before we have been influenced by experiences, other people, our education, or any number of other factors that help form our personalities, we are already reacting differently to stimuli and consequently display different behavioral tendencies. “She’s a much worse sleeper than her sister,” “She cries much more than her brothers and sisters,” or “He feeds really slowly because he’s always distracted by things he sees” are just a few of the kinds of comments I’ve heard from parents describing and comparing their children. So children’s innate temperaments have a substantial influence on them and are observable from Day 1. And a child’s temperament also has an influence on its parents’ behavior, which, in turn, influences how secure the parent–child bond is. This means that differences in temperaments between parents and children can sometimes lead to problems in this relationship and that parents can sometimes become frustrated if they feel that their child has a “difficult” temperament. I can recall a highly sensitive client who was often yelled at and even punished by her stressed and overworked mother because, as a child, she cried far more often that her elder sister and her mother couldn’t bear it.

If we are going to talk about temperament, this, of course, raises the question of what the term temperament actually means. The ancient Greek physician Hippocrates ( c. 460–375 BC) was one of the first Western thinkers to tackle the question of temperament, developing his own temperamental theory. Since then, countless writers, philosophers, doctors, psychologists, and academics have explored the idea of temperaments and defined a range of different temperamental traits. To this day, research into human temperaments remains an important area of developmental psychology.

Professor Silvia Schneider of Ruhr University, Bochum, offers a clear and easily comprehensible definition of what temperament actually is: “The word temperament describes a constitutional factor that is inherited and which predisposes someone to react to situations and people in specific ways. Temperamental traits can be understood as those that form the basis for the development of the personality, appear early in life, are stable over time, and which are influenced by biological factors.” 1

Simply put, our temperament is the basis of our personalities and the complex interaction between our temperament and our environment forms our personality. 2Researchers disagree on exactly how stable temperamental traits are. There is, nevertheless, broad agreement on the fact that our temperament represents a relatively permanent tendency that affects how we react and interact with the world from early childhood onward.

Carl Jung, the Swiss psychiatrist and psychoanalyst, was the first person to talk about “innate sensitivity.” Jung believed that around 25 percent of all people are born with a particularly sensitive disposition and that this sensitivity has a decisive influence on people’s worldview. Jung introduced the terms introversion and extroversion into personality psychology to describe two different natures that influence people’s perception, intuition, thinking, feelings, and behavior. According to Jung, introverted people are more inclined to direct their energy and their attention inward and toward their inner processes (feeling and thinking, for instance), whereas extroverted people are more strongly inclined to direct their physical energy outward. 3Since then, numerous researchers into personality traits, including Jung himself, have continued to develop the concept of introversion and extroversion.

One of these researchers was the German-born British psychologist Hans Jürgen Eysenck, who related Jung’s concept to Hippocrates’s temperamental theory and believed that there is a neurological basis for the differences between introverted and extroverted people. In 1968, he described the typical introvert as someone who is quiet, introspective, rather reserved (except with very close friends), and loves books more than people. Introverts tend to make plans in advance, be cautious, and not like impulsive actions. They don’t like arousal, approach daily life with a certain seriousness, and value a well-ordered life. Eysenck describes the typical extrovert as sociable, as someone who likes events, has many friends, needs people to talk to, and doesn’t like being alone. Extroverts crave excitement, are constantly making the most of opportunities, react spontaneously, take risks, and are generally more impulsive. 4

As such, Jung’s concept of innate sensitivity began to shift to a difference between observable extroverted and introverted behaviors in people. Jung’s theory of extroversion and introversion continues to be hugely important, and it has had a decisive influence on research into both temperament and personality. In the most commonly used model of personality psychology, the Big Five, extroversion is included alongside openness to experience, conscientiousness, agreeableness, and neuroticism. And there continues to be widespread interest in the concept of extroversion and introversion outside of academic research, as evidenced by the success of books like Susan Cain’s brilliant bestseller, Quiet: The Power of Introverts in a World That Can’t Stop Talking .

Another researcher influenced by Jung’s theory of extroversion and introversion is Jerome Kagan, professor of developmental psychology at Harvard University. Based on the results of his longitudinal studies, begun in the 1970s, Kagan differentiates between two groups of children: inhibited children and uninhibited children. According to Kagan, these two types represent relatively stable temperamental traits that follow us throughout our lives and that can only be influenced by environmental factors to a limited extent. Schneider summarizes Kagan’s results as follows:

Behavioral inhibition can be defined as a withdrawn, cautious, avoidant, and shy behavior in new and unfamiliar situations, such as meeting new people or dealing with unfamiliar objects and environments. This behavior can already be evident at the age of eight months. In babies, behavioral inhibition manifests itself as an easily triggered irritability (for instance, crying or screaming), in infants as shy and anxious behavior, and in school children as socially withdrawn behavior. The stability of this temperamental trait into adolescence has been demonstrated in a number of studies. 5

According to Kagan, around 20 percent of all children exhibit inhibited behavior. These children have a lower arousal threshold than other children, particularly in unfamiliar situations. This means that their sympathetic nervous systems respond in a more reactive way to these stimuli. The sympathetic nervous system is part of the autonomic nervous system, alongside the parasympathetic nervous system, which is involved in activities such as digestion when we are at rest. The sympathetic nervous system, on the other hand, is involved in stimulating activities that affect our heart rate, blood pressure, muscle tone, and metabolism. When confronted with an unfamiliar situation or a new stimulus, inhibited children—in contrast to uninhibited children—will exhibit shy, cautious, and withdrawn behavior, while simultaneously exhibiting increased stress symptoms in their sympathetic nervous system, such as muscle tension and a heightened heart rate.

Numerous other researchers on temperament, including the psychiatrists Alexander Thomas and Stella Chess, have developed a range of different categories and models to differentiate between various temperamental traits. In their longitudinal study on temperamental development, which ran from 1956 to the 1990s in New York, Thomas and Chess observed the behavioral characteristics of babies and defined nine new temperamental dimensions. 6They were able to assign a clear temperamental type to 65 percent of the babies: 40 percent were categorized as “easy” babies, 10 percent were “difficult” babies, and around 15 percent were categorized as “slow to warm up.” In a book on high sensitivity, you can probably guess that it is the babies who were “slow to warm up” that we are interested in. The babies in this group were withdrawn when they had to deal with new people or situations and needed more time to get used to them. This means that they were initially behaviorally inhibited, but they then particularly benefitted from repeated contact and increased familiarity with new situations, people, or objects. 7, 8Their activity levels were lower and their sensitivity to subtle stimuli greater, and they reacted less emotionally than babies with “difficult” temperaments.