4. Isolated monkeys

Harry Harlow carried out some celebrated experiments rearing Rhesus monkeys away from their mothers, in order to explore the ideas put forward by Bowlby. Apart from being isolated from contact with others, the material needs of the monkeys were careful provided for. The results were very striking: the monkeys brought up in isolation showed an extreme level of behaviour disturbance. When introduced to other, normal, adult monkeys they were either fearful or hostile, refusing to interact with them. They would spend much of their time sitting huddled in the corner of the cage, resembling in their posture human beings suffering from schizophrenic withdrawal. They were unable to mate with other monkeys, and in most cases could not be taught to do so. Females who were artificially impregnated little or no attention to their young.

In order to see whether it was absence of the mother that produced these abnormalities, Harlow brought up some young monkeys in the company of others of the same age. These animals showed no sign of disturbance in their later behaviour. Harlow concluded that what matters for normal development is that the monkey has the opportunity to form attachments to another or others, regardless of whether these include the mother herself (Harlow and Zimmerman, 1959);

5. Deprivation in human infants

It cannot be assumed that what happens with monkeys will occur in the same way among human infants (Harlow didn’t suggest that his results demonstrated anything conclusively about human experience). Nevertheless, research on human children suggests parallels with the observations Harlow was able to make, although demonstrating long-term consequences of deprivation in infancy is obviously difficult (since experimentation is not possible). Studies of human infants tend to bear out the conclusion that what matters for the security of a child is the development of consistent patterns of early emotional attachment. These need not be with the mother herself, and therefore the term ‘maternal deprivation’ is somewhat misconceived. It is the opportunity to form stable, emotionally close, relations with at least one other human being in infancy and early childhood which matters. The immediate effects of deprivation of such ties on young children have been well documented. Research on children admitted to hospital has shown that emotional distress is most pronounced for children of between six months and four years of age. Older children tend to suffer less severely and in a less prolonged way. The reactions of young children are not just due to the effects of being placed in a strange environment; the same consequences are no found if the mother or other familiar people who have been caring for the child are continuously present in the hospital.

6. Long-term influences

While the evidence about long-term influences is more ambiguous, in general it seems that deprivation of close early attachments often produces behaviour disturbances of a lasting kind. Only in rare cases, such as those of the ‘wild boy of Aveyron’ and Genie, are human children more or less completely isolated from other people. So we would not expect to find a clear demonstration of the profound disturbances which affected Harlow’s animals. However, there is considerable evidence to show that children without stable attachments in infancy show linguistic and intellectual retardation, as well as experiencing difficulties later in forming close and lasting relationships with other. Reversal of these characteristics becomes progressively more difficult after the age of about six to eight.