Individual differences in human motivation and emotion that appear early in life, usually thought to be biological in origin. Temperament is sometimes considered the biological or physiological component of personality, which refers to the sum total of the physical, emotional, mental, spiritual, and social dimensions of an individual.
Ancient Greek and Roman physicians invoked nature, claiming that the proportions of the various humors or fluids in the bodies influenced personality. They thought that there were four basic temperaments—sanguine (cheerful), choleric (irritable), melancholic (gloomy), and phlegmatic (apathetic)—which were determined by the predominance of blood, yellow bile, black bile, and phlegm respectively in the person's physical constitution. The ancient theory survives in the form of such expressions as "being in a bad (or good) humor."
The theory of four bodily humors did not survive the rise of scientific medicine in the seventeenth century as an explanation for differences in human temperament, but it has not been replaced by any single universally accepted theory of personality either. During most of the twentieth century, political ideology, discoveries about the learning or conditioning capabilities of infants, and the emergence of psychoanalytic theory, which emphasized the importance of early experience, all combined to discredit biological explanations for human motivation and emotion. Nurture and socialization became the favored explanations of differences in temperament.
There was, however, a resurgence of interest in the contribution of temperament to children's development after the 1950s. Temperament came to be summarized as the biological dimension of personality. It was seen as a predisposition that allows two individuals to experience the same objective event very differently within the range of normal behavior and development.
Specific approaches to temperament
THE NEW YORK LONGITUDINAL STUDY Suspecting that inherent individual differences among their young patients contributed to their developmental paths, two child psychiatrists, Alexander Thomas and Stella Chess, designed a study that challenged the nature-nurture dichotomy. Beginning in 1956 and ultimately publishing their research in Temperament and Development in 1977, Thomas and Chess collected longitudinal data from over 100 children, following them from infancy through early adulthood. Using extensive clinical interviews to gather information about children's behavior as well as parents' values and expectations, they examined what they termed the goodness of fit between the individual child and his or her environment.
Thomas and Chess found that children could be rated on each of nine dimensions even in infancy:
- Activity level: The child's general level of energy and movement—whether he or she is quiet, always "on the go," or somewhere in-between.
- Rhythmicity: The child's regular biological patterns of appetite and sleep—whether the child gets hungry or tired at predictable times.
- Approach/withdrawal: The child's usual response to new people or situations—whether the child is eager for new experiences or shy and hesitant.
- Adaptability: The child's ability and pace in adjusting to changes in schedules or transitions from one activity to another.
- Threshold of responsiveness: The child's level of sensitivity to such physical stimuli as sounds, smells, and lights. For example, some children are easily startled by sudden noises while others are less sensitive to them. Some children are pickier about food than others.
- Intensity: The child's responses to people or events. Some children react strongly and loudly to even minor events while others are less demonstrative or openly emotional.
- Quality of mood: The child's overall worldview, whether positive or negative. Some children tend to focus on the negative aspects of a situation while others are more positive or hopeful. Some children tend to approach life in a serious or analytical fashion while others respond to their immediate impressions of situations.
- Distractibility: The child's ability to pay attention to tasks or instructions even when the child is not particularly interested in them. Some children have shorter attention spans than others.
- Persistence: The child's ability to continue with an activity in the face of obstacles or problems. Some children are more easily discouraged by difficulties than others.
Thomas and Chess combined the patterns of children's ratings on each of these nine dimensions to distinguish three major temperamental types:
- Easy children: About 40 percent of the NYLS sample displayed a temperamental profile marked by regularity, ease of approach to new stimuli, adaptability to change, mild to moderate mood intensity, and a generally positive mood. This profile characterizes what Thomas and Chess call the easy child.
- Difficult children: About 10 percent of children showed a very different profile and were called difficult children. They had irregular patterns of eating and sleeping, withdrew from new stimuli, did not adapt easily to change, and reacted intensely to changes. Their overall mood was often negative.
- Slow-to-adapt children: Children who were slow to warm up comprised the third temperamental group, about 15 percent of Thomas and Chess's sample. These children tended to withdraw from new stimuli and had difficulty adapting to change, but their reactions were of mild intensity and gradually became either neutral or positive with repeated exposures to the new event or person.
Some researchers prefer the terms flexible, active or feisty, and cautious instead of the somewhat judgmental terms of easy, difficult, and slow-to-adapt, respectively.
Clearly, these three temperamental types that Thomas and Chess identified did not include all of the variations seen in children across the entire sample. About one third of the children showed mixed profiles. Nonetheless, these temperamental classifications became highly influential in child development research. Perhaps the greatest contribution of the NYLS, however, was Thomas and Chess's emphasis on "goodness of fit"; that is, they maintained that the child's temperament by itself was not the most important consideration in his or her growth and development, but the extent to which that temperament agreed with the values, expectations, and style of the child's environment, whether family , childcare setting, school, or culture. For example, a quiet and serious child fits in well with a family of scholars or intellectuals, whereas an intense, active, and easily distracted child may not be accepted as readily in the same family context. In terms of culture, some ethnic groups place a high value on self-control and relating well to others, while other groups emphasize assertiveness and independence. A child who has a high energy level and reacts intensely to persons and events will have a better fit with the second group than with the first. The notion of goodness of fit also helps to explain why some children in a given family seem to get along better with their parents than their siblings do. Even though temperament is thought to be rooted in biology, different children in the same family may have very different temperaments.
TRAIT APPROACHES Some approaches to the study of temperament emphasize traits; that is, they assume that temperamental qualities can be rated as persisting within individuals across time in a variety of situations. In 1984, as published in their book, Temperament: Early Developing Personality Traits , Arnold Buss and others considered temperaments to be heritable and stable personality profiles—profiles that are genetically influenced and relatively unchanging over time. These researchers used maternal questionnaires to gather information on children's emotionality, activity, and sociability, traits they regarded as the fundamental dimensions of temperament. Interestingly, Buss and Plomin suggested that children who are rated as extreme on these dimensions may be qualitatively different from those whose scores lie closer to the middle.
Basic emotions were at the core of H. Hill Goldsmith and Joseph Campos's conception of temperament. In 1983, in an essay included in Socio-Emotional Development, they described temperament in terms of individual differences in experiencing and expressing such primary emotions as anger, fear , and pleasure. Goldsmith and Campos, however, emphasized the speed and intensity of children's responses to stimuli as well as the specific emotions involved. Their evaluations were based on three measurements: threshold (the amount of stimulation the child requires before responding); latency to respond (how rapidly the child reacts to the stimulus); and intensity of response.
In 2004, Mary Rothbart emphasized reactivity and self-regulation as core processes in organizing temperamental profiles. These processes, she believed, can be seen in six significant infant behaviors: smiling; distress when confronted by limitations; fear; activity level; soothability, and duration of orienting (how long the baby plays with or pays attention to a single object). Her Infant Behavior Questionnaire (IBQ), which was developed in the early 1980s, remained, as of 2004, one of the most widely used methods of assessing temperament in infants between the ages of three months and 12 months. In the first version of the IBQ, published in 1981, parents were asked to rate the frequency of these temperament-related behaviors in their child over a two-week period. The revised version of the IBQ, known as the IBQ-R, was developed by Rothbart and her colleague Masha Gartstein in the early 2000s. The IBQ-R expanded the original six measures of temperament to 14. The new measurements include the following:
- Approach: The infant's excitement and looking forward to a pleasurable experience or activity.
- Vocal reactivity: The baby's level of vocal responses to stimuli in its daily routine.
- Perceptual sensitivity: The infant's ability to detect low-intensity stimuli in its environment.
- High-intensity pleasure: The infant's reactions to pleasurable stimuli or activities of high intensity, such as loud music or bright lights.
- Low-intensity pleasure.
- Cuddliness: The infant's physical and emotional responses to being held or cuddled by a parent or caregiver.
- Rate of recovery from distress: How long it takes the infant to return to a normal level of emotion after an exciting or upsetting experience and how readily the child falls asleep.
In contrast to Goldsmith and Campos, Rothbart emphasized cognitive processes in children as the key to understanding temperament rather than emotions by themselves. For Rothbart and her colleagues, the infant's ability to focus its attention is the basis of its later ability to regulate its reactions to people and events. In Rothbart's view, what she calls the attentional system allows the child to regulate his or her outward behavior as well as internal reactions to stimuli. As children mature, they develop the ability to turn their attention to alternative strategies when they are frustrated and to make plans in order to achieve their goals. Different patterns of self-regulation in turn help to explain differences in temperament.
Goldsmith and Rothbart collaborated to develop an assessment tool to gauge temperamental dimension based on systematic observations of behaviors elicited under standard laboratory conditions (for example, how a child reacts to a mechanical spider). The development of an observational protocol or test for assessing temperamental characteristics offers an advantage over reliance on questionnaires. When parents describe their children's behavior, they are influenced by their feelings about the child as well as their observations. In addition, the parents' reports include many sources of information such that reports of the child's behavior cannot be easily separated from the parents' biases, values, or expectations.
TYPE APPROACHES Another major approach to the study of temperament distinguishes among types of people characterized by different patterns of behavior. In the 1990s, in Galen's Prophecy , Jerome Kagan and his colleagues studied two types of children whom they defined as inhibited and uninhibited (or exuberant) respectively. Kagan's group studied the development of these two types of children through adolescence as well as the infant profiles that predicted the children's behavior at later ages. At early ages, inhibited children cling to their mothers and may cry and hesitate when confronted with unfamiliar persons or events. These children appear to be timid and shy and represent about 20 percent of volunteer Caucasian samples. Uninhibited or exuberant children, on the other hand, approach new events and persons without hesitation or trepidation. They appear fearless and sociable and represent about 40 percent of volunteer samples. Kagan's observations of these children over time indicated that these characteristic profiles tended to continue, although the display of temperamental tendencies varied in accordance with the child's developmental level. An older inhibited child or teenager, for example, may not cling to his or her mother or cry when coming to an unfamiliar laboratory but may hesitate to talk to the examiner and may smile infrequently.
Interestingly, Kagan found that the behavioral profiles of these children were accompanied by physiologic profiles that suggested different levels of reactivity in the children's central nervous systems, particularly in regard to fear and stress reactions. Inhibited, compared to uninhibited, children tended to have higher and more stable heart rates, higher levels of stress-related hormones like cortisol and norephinephrine, larger changes in blood pressure in response to stressors, and measurable tension in their voices when speaking under mildly stressful conditions. These differences seemed to support the contention that temperamental categories have a biological dimension.
Although young infants are not sufficiently mature to demonstrate timidity in response to new experiences, the reactivity of the structures in the human nervous system that are thought to underlie inhibited and uninhibited temperaments may appear at early ages. When infants are exposed to variations in the sights and sounds in their environment, some become aroused and demonstrate this arousal by moving their arms and legs and fretting or crying. Other infants remain calm, relatively motionless, and do not cry. Those who are highly reactive to stimulation tend to become inhibited in their reactions to novelty and uncertainty at later ages. Those whose reactivity level is low in infancy tend to grow into children who remain relaxed in novel situations so that they appear outgoing and uninhibited.
MALLEABILITY OF TEMPERAMENT Malleability refers to the extent to which temperament can be influenced or reshaped by later life events. The reader should note that the continuity of temperamental profiles from infancy through later ages is a group phenomenon; that is, individual children may change and become more or less inhibited while the groups of children remain distinct on average. Neither temperament nor biology is destiny. Temperament and environment both influence development, although relatively few researchers have studied the interaction of these two influences as of the early 2000s.
Research in early 2000s about temperament
In the early 2000s, research on temperament in children and adolescents is making use of new brain imaging technology to expand understanding of the biological processes that influence emotional self-regulation and task-related activities. This technology is known as functional magnetic resonance imaging (fMRI). Functional magnetic resonance imaging is based on the fact that activity in a specific part of the brain is accompanied by an increased flow of blood to that region. As the blood flow increases, the amount of deoxyhemoglobin, a form of hemoglobin that has lost its oxygen content, decreases in the affected area of the brain. Since the amount of deoxyhemoglobin in the blood affects the magnetic resonance image signal, it can be used as the source of the signal for fMRI. This discovery means that fMRI studies can be conducted without injecting radioactive materials into a subject's blood. In addition, it means that usable MRI images can be obtained in a very short period of time (1.5–2 minutes on average) rather than the longer periods of testing required when radioactive materials are used.
FMRI has many beneficial applications, ranging from more accurate planning for brain surgery to more effective pain management . In terms of the study of temperament, fMRI allows researchers to study such complex brain activities as problem-solving as well as visual and auditory (hearing) perception. In 2003, the National Institute of Mental Health (NIMH) began a study that uses fMRI technology on 60 children and adolescents between the ages of nine and 16. The study is designed to test the hypothesis that differences in temperament related to differences in brain functioning put some children at an increased risk of certain psychiatric disorders later in life. The type of child that Kagan's research group identified as inhibited, for example, appears to have the same pattern of disturbed nerve cell activity that has been identified in adults diagnosed with mood or anxiety disorders. Specifically, inhibited children seem to have a higher level of activity in a part of the brain called the amygdala, which regulates emotion, and a lower than average level of activity in the prefrontal cortex, which governs a person's ability to express emotions. Exuberant children, on the other hand, are thought to have a relatively high level of activity in the prefrontal cortex in response to certain stimuli.
In addition to its usefulness in studying the parts of the brain that are activated by sensory perception, thinking, and emotional responses to various stimuli, fMRI may also be helpful in distinguishing between problem behaviors in children that are rooted in temperament and behaviors that indicate a psychological problem. As of the early 2000s, research in the area of temperament has not been closely coordinated with research in childhood psychiatric disorders; as a result, both the causes and treatments of these disorders were, as of 2004, not well understood. Child psychiatrists have already observed that avoidant personality disorder (APD) and generalized anxiety disorder (GAD) are closely linked to the inhibited type of temperament as described in Kagan's work. To give another example, such temperamental traits as irritability and strong negative reactivity are thought to contribute to the development of oppositional defiant disorder in some children. Lastly, attention deficit/hyperactivity disorder is thought to be heavily influenced by genetic factors affecting the child's temperament, including the production and metabolism of certain neurotransmitters in the brain that affect the child's ability to focus his or her attention.
The following are some of the problems that may arise in connection with differences in children's temperaments:
- Parents tend to regard certain characteristics as negative rather than as potentially positive. For example, a child's slowness to adapt may be seen as a drawback rather than as a protection against the dangers of impetuosity or being overly influenced by peer pressure.
- Behavioral problems are related to a poor fit between parent and child. Pediatricians often see families in which a vicious circle of negative interactions develops. The most common example is an angry reaction to a difficult child's aggressiveness or restlessness that takes the form of scolding or spanking. The child reacts to the parents' negative actions by increased aggressiveness, temper tantrums , or stubbornness. Another common pattern is the shy or inhibited child who becomes even more withdrawn when parents react to the shyness by lecturing or shaming the child.
- Favoritism becomes a factor when some parents find it much easier to relate to a child with a flexible temperament or one whose temperament matches their own than to a child who does not fit in as well. They may ignore the child they find less agreeable or punish him or her unfairly.
Common parental concerns about evaluations of their children's temperament include the following:
- Fears about labeling or stigmatization: Some parents are concerned about the reactions of teachers or other adults if their child is identified as "difficult." This fear is one reason why some researchers prefer to describe children in this category as "active" or "feisty" rather than to use the negative term difficult.
- Concerns about fairness: Parents whose children have different temperaments are sometimes concerned that treating the children differently will be perceived as unfair or unjust.
- Concerns about the parent-child bond: Some parents worry about their ability to relate to a child with a difficult temperament or one whose temperament is different from their own. They may feel guilty about their negative emotional reactions toward such a child and doubt their ability to be good parents.
When to call the doctor
As has already been mentioned, it is not always easy for parents to distinguish between a child with a "difficult" temperament whose behaviors are still within the normal range and a child with a psychiatric disorder. Some guidelines that have been given by pediatricians include the following:
- The specific problem behavior(s) cannot be attributed to the child's developmental stage (such as "the terrible twos").
- The child's problematic behaviors occur frequently.
- The child has several problematic behaviors.
- The child's behaviors are interfering with his or her social and intellectual development.
Amygdala —An almond-shaped brain structure in the limbic system that is activated in stressful situations to trigger the emotion of fear. It is thought that the emotional overreactions in Alzheimer's patients are related to the destruction of neurons in the amygdala.
Cortisol —A steroid hormone secreted by the adrenal cortex that is important for maintenance of body fluids, electrolytes, and blood sugar levels. Also called hydrocortisone.
Goodness of fit —A term first used by Thomas and Chess to describe the importance of children's interactions with their environment as well as their basic temperament in understanding their later growth and development.
Inhibited —A type of child defined by Jerome Kagan and his colleagues as having a low level of responsiveness to strangers, a reluctance to initiate activities, and requiring a long time to relax in new situations. Children with inhibited temperaments appear to be more susceptible to anxiety disorders, depression, and certain personality disorders in their later years.
Malleability —A term that refers to the adaptability of human temperament; the extent to which it can be reshaped.
Neurotransmitter —A chemical messenger that transmits an impulse from one nerve cell to the next.
Norepinephrine —A hormone secreted by certain nerve endings of the sympathetic nervous system, and by the medulla (center) of the adrenal glands. Its primary function is to help maintain a constant blood pressure by stimulating certain blood vessels to constrict when the blood pressure falls below normal.
Personality —The organized pattern of behaviors and attitudes that makes a human being distinctive. Personality is formed by the ongoing interaction of temperament, character, and environment.
Protocol —A plan for carrying out a scientific study or a patient s course of treatment.
Reactivity —The level or intensity of a person's physical or emotional excitability.
Temperament —A person's natural disposition or inborn combination of mental and emotional traits.
Threshold —The minimum level of stimulation necessary to produce a response.
Trait —A distinguishing feature of an individual.
Type —A category used to define personality, usually based on a theory of some kind. Inhibited and uninhibited are examples of personality types.
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Doreen Arcus, PhD