In psychology, temperament broadly refers to consistent individual differences in behavior that are biologically based and are relatively independent of learning, system of values and attitudes. Thomas, Chess, Birch, Hertzig and Korn began the classic New York Longitudinal study in the early 1950s regarding infant temperament (Thomas, Chess & Birch, 1968). The study focused on how temperamental qualities influence adjustment throughout life. Behaviors for each one of these traits are on a continuum. If a child leans towards the high or low end of the scale, it could be a cause for concern. The specific behaviors are: activity level, regularity of sleeping and eating patterns, initial reaction, adaptability, intensity of emotion, mood, distractibility, persistence and attention span, and sensory sensitivity.
Redundancies between the categories have been found and a reduced list is normally used by psychologists today. Thomas, Chess, Birch, Hertzig and Korn (Thomas & Chess 1977) found that many babies could be categorized into one of three groups:
Their research showed that easy babies readily adapt to new experiences, generally display positive moods and emotions and also have normal eating and sleeping patterns. Difficult babies tend to be very emotional, irritable and fussy, and cry a lot. They also tend to have irregular eating and sleeping patterns. Slow-to-warm-up babies have a low activity level, and tend to withdraw from new situations and people. They are slow to adapt to new experiences, but accept them after repeated exposure.
Not all children can be placed in one of these groups. Approximately 65% of children fit one of the patterns. Of the 65%, 40% fit the easy pattern, 10% fell into the difficult pattern, and 15% were slow to warm up. Each category has its own strength and weakness and one is not superior to another. An important aspect of the research of Thomas & Chess (1977) relates to the interaction of child temperament with caretaker personality and parenting style. They proposed that a “match” between the needs of child temperament with parental care would enhance healthy development of self-regulation and the child’s sense of self. This important balance is known as goodness-of-fit.
Temperament and Culture
Thomas, Chess, Birch, Hertzig and Korn found that these broad patterns of temperamental qualities are remarkably stable through childhood. These traits are also found in children across all cultures. Thomas and Chess also studied temperament and environment. One sample consisted of white middle-class families with high educational status and the other was of Puerto Rican working-class families. They found several differences. Parents of middle-class children were more likely to report behavior problems before the age of nine and the children had sleep problems. This may be because children start preschool between the ages of three and four.
De Vries (1974) followed Masai (tribe in East Africa) infants and mothers for a number of years during a period of famine. The researcher found that Masai infants who were more demanding were more likely to survive during periods of ecological stress than infants who were more docile. The researcher suggested that infants who were more aggressive and demanding – or in temperament terms more difficult – were more likely to be fed and to have their needs met than docile infants who might have been easier to ignore. The findings from these cross-cultural studies of temperament demonstrate the interaction between ecology, temperament and culture can impact an individual.