Diary Methods

History of Diary Methods

The earliest diary studies were often observations of infant development recorded by scholarly parents, many of them in the 19th century. Notable scientists including Charles Darwin, Wilhelm Preyer, and Dietrich Tiedemann recorded diaries of their children from birth for some months or years. Early diary studies were small-scale case studies, often involving only one child, and were usually informal, insofar as the aim of the observations and the timing and method for recording was decided in the moment rather than following a systematic plan. One important methodological advance in 19th-century diary studies was the recommendation that diary records should follow some systematic plan, either being recorded at predetermined intervals or following on from predetermined behaviors. Nineteenth-century diaries led to new insights about behavior, particularly during infancy and early childhood.

Perhaps the most famous 19th-century diary was written by Charles Darwin. Darwin recorded observations of his son William from birth to 4 years, noting his reflexes, visual responses to objects such as a candle, and the uncoordinated nature of his motor control during the first days of life. Darwin was interested in the origins of emotional expressions and recorded William’s earliest expressions of anger, fear, and pleasure and the contexts in which each expression was [Page 614]observed. Darwin recounted that at around 4 months of age, his son was pleased and amused by a hiding game in which Darwin threw a pinafore over the child and then removed it, and similarly when Darwin covered his own face and then uncovered it (a peekaboo game). Darwin interpreted his son’s pleasure over the peekaboo game as an indicator of humor and noted his surprise that humor emerged so early in development.

In the 20th century, diary studies became more systematic in aim and scope. Some 20th-century diaries included observations of larger numbers of children, whereas other 20th-century diaries were case studies with a specific aim, such as recording all verbs and sentences uttered by a single child in the second year of life or all humorous utterances from 15 to 30 months. Twentieth-century diaries stimulated influential theories about the developmental origins of a range of abilities, including language, emotions, and motor control, as well as leading to other forms of evidence to test those theories. For example, Jean Piaget’s diary studies of his children’s behavior were the basis for his theories of development, and they influenced the interview techniques that he developed to test those theories.

...