A Synthesis of Major Themes, Findings, and Challenges and a Look Forward

As modern-era research on temperament approaches its 50th anniversary, it is worth remembering some of the forces that propelled temperament into the mainstream of research in psychology, psychiatry, neuroscience, and genetics. Broadly, the emergence of modern temperament research owes to two strands of study with somewhat different goals and emphases. One strand has its origin in child psychology and psychiatry. As described by Rothbart (Chapter 1, this volume), precursors of this tradition included Gesell (1928), Shirley (1933), Bergman and Escalona (1949; Escalona, 1968), and Meili (1957). However, the systematic study of infant and child temperament was not to take off until Thomas and Chess launched their highly influential New York Longitudinal Study, first extensively described 50 years ago in Behavioral Individuality in Early Childhood (Thomas, Chess, Birch, Hertzig, & Korn, 1963). Somewhat paradoxically, the authors initially did not see themselves as temperament researchers. Rather, they set out to study “primary reaction patterns” that could be seen in infants. Their interest was in studying the implications of individual differences in these early patterns for normal and abnormal psychological development, and in exploring the clinical benefits of seeing the child as an autonomous agent (rather than merely as a reflection of parental influences). It was only later that the researchers adopted the term temperament. With its background in child psychiatry and pediatrics, this work paved the way for developmentally oriented work on temperament—an almost entirely new genre of temperament research (Rothbart, Chapter 1, this volume). The second strand had more in common with traditional temperament research, notably in its interest in the hereditary, constitutional, neurobiological, and evolutionary origins of temperament. As described in detail by Zuckerman (Chapter 3, this volume), this strand owed much to the foundational contributions of, among others, Kretschmer (1925), Sheldon and Stevens (1942), Diamond (1957), Eysenck (1967), Gray (1973), Zuckerman (1979), and Strelau (1983). In 1975, A. H. Buss and Plomin provided an influential blend of these two largely unrelated strands of research (Buss & Plomin, 1975; see also Rowe & Plomin, 1977). Placing research on the heritability and biology of adult temperament and the study of child temperament under one roof galvanized the field and helped to forge the identity of the field of temperament as it is known today. Chapter 32