Before proceeding to a systematic discussion of separation anxiety, I wish to emphasize afresh that, although we have become caught up in sketching part of a revised theory of anxiety, this is not the purpose of the paper. Our problem is that of trying to understand separation anxiety. Adequately to formulate a comprehensive theory of anxiety would require a broader approach: in particular it would need to give close attention to anxiety arising from the threat of psychic disorganization.
Ingredients of Separation Anxiety
From the foregoing it will be clear that, according to the hypothesis advanced, separation anxiety is initially a form of primary anxiety, with or without the addition of fright, and that, as the infant develops, anxiety based on learning comes to be added. The reasoning behind this hypothesis has already been presented. My confidence in it springs from my belief that it provides a better explanation of observations of infants and young children than do other hypotheses and is enhanced by the fact that it seems also to fit comparable observations of the young of other species. These will be reviewed.
In very many species of bird and mammal the young show signs of anxiety when removed from their parents. The ‘lost piping’ of young ducklings who have become attached to and have temporarily lost a mother figure is a familiar example. The behaviour of infant chimpanzees in such situations is well recorded. Since it resembles closely, though in slightly exaggerated form, what we see in humans and seems almost certainly to be homologous, it is instructive to examine it. I shall draw on three accounts. Two (Kellogg & Kellogg, 1933; Hayes, 1951) give detailed information about two infant chimpanzees who were ‘adopted’ and brought up in a human home; the third, that by Yerkes (1943), who had prolonged experience of young chimpanzees living in captivity with their own parents, presents generalizations based on many cases. All three agree on the intensity of protest exhibited and, by implication, the anxiety experienced when a baby chimpanzee loses its mother‐figure.
Mrs. Hayes recounts how Vicki, a female whom she adopted at 3 days, would, when aged 4 months, cling to her foster‐mother ‘from the moment she left her crib until she was tucked in at night. … She sat on my lap while I ate or studied. She straddled my hip as I cooked. If she were on the floor, and I started to get away, she screamed and clung to my leg until I picked her up. … If some rare lack of vigilance on her part let a room’s length separate us, she came charging across the abyss, screaming at the height of her considerable ability.’
The Kelloggs, who did not adopt their female chimp, Gua, until she was 7 months old and who kept her for 9 months, report identical behaviour. They describe ‘an intense and tenacious impulse to remain within sight and call of some friend, guardian, or protector. Throughout the entire nine months … whether indoors or out, she almost never roamed very far from someone she knew. To shut her up in a room by herself, or to walk away faster than she could run, and to leave her behind, proved, as well as we could judge, to be the most awful punishment that could possibly be inflicted. She could not be alone apparently without suffering.’
It is of course possible to assume that such behaviour always contains an element of foresight – foresight that physiological needs will not be met. Its strength and immediacy, together with what we know about the primacy of clinging, make this, however, seem unlikely. Furthermore, as was stressed in the previous paper, such a theory is unnecessary.
Except for being less mobile, human infants during the second half of their first year seem to respond similarly to the lower primates. By this age they have become much more demanding of their mother’s company. Often when she leaves the room they are upset and do their utmost to see that contact with her is resumed, either by crying or following her as best they can. Such protest behaviour, I am postulating, is accompanied initially only by primary anxiety.
Later, in both humans and chimpanzees, conditioned and expectant anxiety develop as a result of learning. Their development in chimpanzees is of course well attested. Comparing Gua with their son, who was 2½ months older than she, the Kelloggs report: ‘Both subjects displayed what might be called anxious behaviour (i.e. fretting and crying), if obvious preparations were being made by the grown‐ups to leave the house. This led (in Gua) to an early understanding of the mechanism of door closing and a keen and continual observation of the doors in her vicinity. If she happened to be on one side of a doorway, and her friends on the other, the slightest movement of the door toward closing, whether produced by human hands or by the wind, would bring Gua rushing through the narrowing aperture, crying as she came.’ From this account, it seems clear, by a process of learning Gua was able to anticipate and so to avoid the danger of separation.
Similarly with human infants: it is signs that mother is going to leave them that come to evoke conditioned and expectant anxiety most commonly. At what period during the infant’s first year the capacity for foresight develops is difficult to say. Experiment, however, should be easy. If Piaget’s views are confirmed we should expect it to be present from about 9 months.
Not only do attachment behaviour and anxiety responses appear similar in humans and other species, but the same is true of fright responses in the absence of the mother. In such circumstances the young of many species freeze. Robertson noted this in young children soon after starting observations in 1948. Before a child had got to know him and whilst therefore he was still a frightening stranger, a young child in hospital would occasionally respond to his approach by suddenly becoming immobile, as if trying not to be there, though watching him intently the while. In the course of observations made in connexion with his film study, Robertson (1953a) was able to record this response on two occasions when a strange male colleague approached Laura (he himself by this time having become a familiar and reassuring figure). On each occasion Laura reacted by lying down with eyes closed and failed to respond as she usually did to Robertson’s friendly words: indeed only a flicker of the eyelids showed she was not asleep. When told that the man had gone, however, she at once sat up.
Comparable behaviour in infant rhesus monkeys has recently been reported by Harlow and Zimmermann (1954). In the course of their experiments with model mothers they introduced eight baby monkeys for three‐minute periods ‘into the strange environment of a room measuring 6 feet by 6 feet by 6 feet and containing multiple stimuli known to elicit curiosity‐manipulatory responses in baby monkeys. The subjects were placed in this situation twice a week for eight weeks, with no mother surrogate present during alternate sessions and the cloth mother present during the others. … After one or two adaptation sessions, the infants always rushed to the mother surrogate when she was present and clutched her, a response so strong that it can be adequately depicted only by motion pictures. After a few additional sessions, the infants began to use the mother surrogate as a source of security, a base of operations. They would explore and manipulate a stimulus and then return to the mother before adventuring again into the strange new world. The behaviour of these infants was quite different when the mother was absent from the room. Frequently they would freeze in a crouched position.’ Experimental work has also been done with goats and with similar results.16
If now we return to our account of chimpanzees it is especially to be noticed that, as in the case of Vicki, Gua became strongly attached to a particular figure. In her case it was the male foster‐parent, who in fact did most for her: ‘Her attachment became so strong that she had been in the human environment for fully a month before she would let go of the trouser leg of her protector for any length of time, even though he might sit quietly at a table for as long as an hour. Almost without respite she clung to him in one way or another. If through a temporary lapse in her vigil he should succeed in taking a step or two away from her, it would surely precipitate a frantic scramble after the retreating