Imprinting is the phase at the beginning of an animal’s life, which is also known as the critical period. It is the learning process, which causes, through a stimulus, the social preferences of an animal to become restricted to a particular stimulus or group of stimuli.

Research into imprinting has shown that for social bonding to occur, the animal must find the object, which can be a human, animal, or even an inanimate object, to be stimulating and pleasurable. For the object to be pleasurable being with it or seeing it should produce endomorphines, which comfort the animal. Many factors about the object, such as the movement, brightness, contrast, sound, colour, texture and shape all effect how attractive the stimulus is to the animal. Once this has occurred, for the first time, the object becomes familiar to the animal and they will give the same response every time they see it.

There are two types of imprinting, the most common of which is filial imprinting, and the other is sexual imprinting.

Filial Imprinting

Filial imprinting has mainly been studied in birds, although it does occur in mammals. It occurs at a young age when the animal learns the characteristics of its parents.

In mammals such as mice, rats and rabbits, smell is a major factor in imprinting, as they are born blind and their need for comfort comes through what they smell. Because of this the animal makes the connection between the smell and its parent. This is why, when an animal is being tamed or trained, it is important that early contact and handling is done to build a bond between trainer and animal in the critical period.

The young are vulnerable and need the guidance of a parent, but if done at the right time, a trainer can replace a parent, and the same parent/sibling bond can be made. However, animals should not leave their parents, as this can impact on their development at a later stage.

In birds, it has been shown, that soon after hatching the birds will approach and follow an object to which they are exposed. Movement is more vital in birds than anything else, as a bird will naturally follow a moving parent. This has been proved, in research done by Lorenz, who became imprinted on geese that would then follow him around the room. He also showed that the geese would follow a slowly moving cardboard box. However, coloured balls or illuminated boxes were also effective in causing the geese to approach and form a social preference. Once the gosling approached the imprinted object it would attempt to snuggle up to it, showing the pleasure that even a cardboard box can give to an animal that has become imprinted at the right time.

Research has shown that, while at first the young bird may approach a range of different objects, if it spends enough time with one object it will then remain close to it. Geese are the easiest species to see imprinting in, as they believe they are the same species as whatever they imprint themselves on. This means that if a goose imprints itself on a human, then it will believe it is a human itself. However, if it sees other geese, then it will see that it is a goose sibling. There are three different scenarios that affect how a goose grows. These are:

A goose brought up with other geese

A goose brought up by a human with goose siblings

A goose brought up by a human on its own

A simplified way of showing this is as follows:

Sexual Imprinting:

Sexual imprinting also occurs at a young age, and also up to mating age. This is where the animal forms a preference towards mates to those that where present when the animal was reared. This is seen in rodents, who have a preference to those who have the same smell as those present in the group during rearing.

The reason for sexual imprinting is to ensure that animals only mate with their own species. However, if foster parents raise an animal, it will then have a sexual preference for the foster species. This is what happened with Lorenz’s geese as they tried to mate with him as they became older.

Continuing the cycle, as shown previously can show this:

In many species, the male will leave, leaving the female to raise the young. Females, brought up by their mother, learn to recognise potential future mates from siblings and neighbours. However, sexual imprinting allows this to be done without inbreeding, which would weaken the species.