Maternal Imprinting

These studies have involved mammals and birds, warm-blooded species that
have high social bonding, which seems to be a prerequisite for imprinting.
The most famous imprinting studies were performed by the animal behaviorists
and Nobel laureates Konrad Lorenz (1903-1989) and Nikolaas Tinbergen
(1907-1988). They and their many colleagues detailed analyses of
imprinting in a variety of species, in particular waterfowl such as geese and
ducks. The maternal imprinting behavior of the newborn gosling or duckling
upon the first moving object that it sees is the most striking example of
imprinting behavior.

The maternal imprint is the means by which a newborn identifies its
mother and the mother identifies its young. In birds, the newborn chick follows
the first moving object that it sees, an object that should be its mother.
The critical imprinting period is within a few hours after hatching. The
chick visually will lock on its moving mother and follow it wherever it goes
until the chick reaches adulthood. The act of imprinting not only allows for
the identification of one’s parents but also serves as a trigger for all subsequent
social interactions with members of one’s own species. As has been established
in numerous experiments, a newborn gosling that first sees a female
duck will imprint on the duck and follow it endlessly. Upon reaching
adulthood, the grown goose, which has been raised in the social environment
of ducks, will attempt to behave as a duck, even to the point of mating.
Newborn goslings, ducklings, and chicks can easily imprint on humans.
In mammals, imprinting relies not only visual cues (specific visible physical
objects or patterns that an animal learns to associate with certain concepts)
but also on physical contact and smell. Newborn infants imprint
upon their mothers, and vice versa, by direct contact, sight, and smell during
the critical period, which usually occurs within twenty hours following
birth. The newborn and its mother must come into direct contact with each
other’s skin and become familiarized with each other’s smell. The latter
phenomenon involves the release of special hormones called pheromones
from each individual’s body. Pheromones trigger a biochemical response in
the body of the recipient individual, in this case leading to a locked identification
pattern for the other involved individual. If direct contact between mother and infant is not maintained during the critical imprinting period,
then the mother may reject the infant because she is unfamiliar with its
scent. In such a case, the infant’s life would be in jeopardy unless it were
claimed by a substitute mother. Even in this situation, the failure to imprint
would trigger subsequent psychological trauma in the infant, possibly leading
to aberrant social behavior in later life.