Animal studies

• Lorenz (1935)

  gosling eggs, half hatch in incubator seeing him first, half hatched by mother, each group imprints and stays imprinted even when mixed with siblings from other group (returning to imprinted figure), critical period of 2 days
• Harlow (1959)

  Two wire mother's, one just wire one with cloth, rhesus monkeys in two groups of 4, groups fed from milk bottle from either wire or cloth mother, regardless of group most monkeys spent time with cloth, ran to cloth when frightened, evidence for attachment based on comfort rather than food, experiment monkeys went on to be socially inept, sexually abnormal, and bad parents later on (did not cradle them), critical attachment period before 6 months
• Guiton (1966)

  leghorn chicks exposed to yellow gloves for feeding became imprinted, animals not born with innate preference for attachment figure, early imprinting linked to later reproductive behaviour, some chicks tried to mate with yellow gloves, able to reverse this behaviour after spending more time with own species
• Hoffman (1996)

  imprinting actually a more ‘plastic and forgiving mechanism’
• Harlow’s study had confounding variable, the two mother's head differed in appearance with more than just cloth and wire, looked very different, possibility rhesus monkeys preferred cloth as the head was more ‘attractive’, lack internal validity