The 4 WHY’s of Age-Linked Regression Periods in Human Infancy

SpeakerFrans Plooij (International Research-institute on Infant Studies)
SummaryWednesday, 12:00 noon at NESCent, Ninth Street and Main Street, Erwin Mill Building, 2024 W. Main Street, Room A103. For more information, call 919-668-4551.

Speaking in terms of human evolution, the phenomenon of regression periods is old. In the literature regression periods are reported for at least 12 primate species and 1 non-primate mammal. Regression periods are characterized by a temporary increase in proximity to the mother and sucking. It will be described in more detail for free-living chimpanzee infants.

The development of age-linked regression periods in human infancy is described. The ages at which the regression periods occur have been confirmed by independent research groups in three other countries. Mother-infant conflict periods shortly follow the regression periods. These are vulnerable periods: peaks in illness and Sudden Infant Death have been found at approximately the same ages.

The causation of the age-linked regression periods has to do first and foremost with sudden brain changes such as a sudden, sharp increase in head circumference at or shortly before the ages at which the regression periods start. A Hierarchical Perceptual Control Theory (HPCT) model of the development of the human nervous system during the sensorimotor period is presented, together with preliminary experimental studies testing the HPCT-model. To complete this model of human sensorimotor development, the complementary reorganisation model is presented where the trilogy of mind, that is affect, cognition, and conation, finds its place.

The function of regression periods is discussed. Regression periods are not only difficult periods for the baby, but also very worrying, annoying, and irritating periods for the parents. This draws the attention of the parents towards the baby and this, in turn, might enhance survival directly or indirectly, through promoting the intelligence and prosocial behaviour of the infant. These measurable effects were shown in an experimental Parenting Support and Education Program.