1926 Sigmund Freud presents the psychoanalytic theory of “cupboard love,” suggesting that infants become attached to caregivers because they fulfil physiological needs.
1935 Konrad Lorenz’s research shows that nonhumans form strong bonds with the first moving object they encounter.
1959 Harry Harlow’s work demonstrates that macaque monkeys separated from their mothers in infancy develop social and emotional problems.
1978 Michael Rutter shows that children can become strongly attached to a variety of attachment figures (such as fathers, siblings, peers, and inanimate objects).
In the 1950s, the prevailing ...