Regresssion Periods in Human Infancy: An Introduction
The regression phenomenon discussed in this book is, evolutionarily speaking, probably very old and has been observed among humans, primates, and nonprimate mammals. Horwich (1974) reported specific regressive periods (peaks in nipple contact among 12 species of monkey) in primate behavioral development and also indicated that these peaks occur at similar times in development and become less pronounced as the infant develops. Regression, according to Horwich, specifically refers to the return to a high frequency of mother-infant contact, characteristic of the earliest period, and is supposed to rest on graded emotional states of insecurity. Later, van de Rijt-Plooij and Plooij (1987) expanded Horwich's findings when they reported they had found regression periods when studying free-ranging chimpanzees. Before each "leap" in independence, when a sharp decrease in mother-infant body contact was found, a regression period occurred followed by aperiod of mother-infant conflict over body contact. Regression was expressed, first, in a temporary shift back to mainly staying doser to mother, and, second, in a temporary increase in the amount of ventro-ventral contact.