The purpose of this study is to answer the following questions. First, do normal human infants go through periods of disorganization/regression, how are they expressed, and at what ages are they found? Second, how do mothers experience these periods?

An impressive consensus was found in 15 mother-infant pairs on the ages when the infant is experienced as 'difficult'. These difficult periods were mainly characterized by an increase in crying and a decrease in independence and amount of sleep. Other infant behaviours that were reported during some of these periods for some of the infants were fear for other people, childish behaviours, decrease in amount of food intake, problems with changing/dressing, decrease in activity, peak in cuddling mother, and peak in cuddling objects. The reports by the mothers were validated through direct observation in the homes.

These findings have important practical and theoretical implications. The link between infantile regression and developmental transitions is discussed.