Bowlby goes on to describe what happens when the mother comes back:
“Nevertheless, provided the period of separation is not too prolonged, a child does not remain detached indefinitely. Sooner or later after being reunited with his mother his attachment to her emerges afresh. Thenceforward, for days or weeks, and sometimes for much longer, he insists on staying close to her. Furthermore, whenever he suspects he will lose her again he exhibits acute anxiety.”[17]
We see similar attachment behavior in our various primate relatives—such as chimpanzees, gorillas, and orangutans—as well as in our more distant cousins, the monkeys. We should also note Harry Harlow’s discovery that, given no other alternative, a monkey will become attached to an object that has no behavior at all, but does have some ‘comforting’ characteristics. This would seem to confirm Bowlby’s view that attachment does not stem from ‘physiological needs’—unless we amend this to include the infant’s need for what Harlow calls comfort contact.[18]
John Bowlby: “The very detailed observations made by Jane Goodall of chimpanzees in the Gombe Stream Reserve in central Africa show not only that anxious and distressed behavior on being separated, as reported of animals in captivity, occurs also in the wild but that distress at separation continues throughout chimpanzee childhood. … Not until young are four and a half years of age are any of them seen traveling not in the company of mother, and then only rarely.”
When the mother and child have more distance between them, they maintain their connection with a special ‘hoo’ whimper to which the other promptly responds—as Jane Goodall herself reports:
“When the infant ... begins to move from its mother, it invariably utters this sound if it gets into any difficulty and cannot quickly return to her. Until the infant’s locomotion patterns are fairly well developed the mother normally responds by going to fetch it at once. The same sound is used by the mother when she reaches to remove her infant from some potentially dangerous situation or even, on occasion, as she gestures it to cling on when she is ready to go. The ‘hoo’ whimper therefore serves as a fairly specific signal in re-establishing mother-infant contact.”[19]
What happens in other animals? Early in the 1930s Konrad Lorenz observed that a recently hatched chicken, duck, or goose will become “attached” to the first large moving object it sees, and will subsequently follow that object around. He called this “imprinting” because it occurs with such remarkable speed and permanence. Here are some of his observations.[20]
The chick quickly starts to follow the moving object.
Imprinting begins soon after hatching.
The period for imprinting ends a few hours later.
The effect of imprinting is permanent.
To what objects will the chick get attached? That moving object will usually be a parent—but if the parents have been removed, then the object could be a cardboard box, or a red balloon—or even Konrad Lorenz himself. During the next two days, as the gosling follows its parents, it somehow learns to recognize them as individuals and not follow any other geese. Now when it loses contact with the mother it will cease to feed or examine things, and instead will search and make piping sounds, as though distressed at being lost. Then the parent responds with a special sound—and Lorenz observes that this response must come quickly to establish imprinting. Later this call is no longer needed, but in the meantime it serves to protect the chick against becoming attached to an unsuitable object, such as the moving branch of a tree.
These ‘piping’ sounds, like the ‘hoo’ signals in Jane Goodall’s notes, suggest that other ways to communicate could have co-evolved from attachment signals. In any case, these types of birds can feed themselves soon after they hatch—so imprinting is independent of being fed.
As for when the imprinting period ends, R.A.Hinde discovered that those chicks eventually become fearful of unfamiliar moving things—which led him to suspect that imprinting stops when this new fear forestalls further ‘following’. Similarly, many human babies show a long period of fear of strangers that begins near the start of the second year.[21]
Bowlby’s research on young children showed that when they are deprived of imprimers for more than a few days, they may show signs of impairments for much longer times. He also cites similar results when other researchers separated infant Rhesus monkeys from their mothers:
“From all these findings[22] we can conclude with confidence not only that a single separation of no longer than six days at six months of age has perceptible effects two years later on rhesus infants, but that the effects of a separation are proportionate to its length. A thirteen-day separation is worse than a six-day; two six-day separations are worse than a single six-day separation.”
Remarkably, even badly mistreated children (and monkeys) may remain attached to abusive imprimer.[23]
To what extent did human attachment-based learning evolve from older forms of pre-human imprinting? Of course, humans are very different from birds, yet the infants of both share similar needs—and there may have been precursors of this in some earlier warm-blooded dinosaurs. For example, Jack Horner[24] discovered that some of these constructed clusters of bird-nest like structures. Further progress in genomics might help us reconstruct more of this history.
Returning to the human realm, we should ask how infants distinguish potential imprimers. Although some researchers have reported that infants can learn to recognize the mother’s voice even before the time of birth, it is generally though that newborns first learn mainly through the senses of touch, taste, and smell—and later distinguish the sound of a voice and start to react to the sight of a head or a face. One first might assume that this is done by detecting features like eyes, nose, and mouth, but there is evidence that it is more complex than that.[25]
Francesca Acerra: “4-day-old neonates look longer at their mother’s face than at a stranger’s face—but not when the mother wears a scarf that hides the hair contour and the outer contour of the head.”[26]
This researcher found that those infants react less to the features of the face, and more to its larger-scale, overall shape; it was not until two or three more months that her subjects distinguished particular faces.[27] This suggests that our visual systems involve different methods at different stages of development—and perhaps the ones that are first to operate serve mainly to get the mother attached to the child! In any case, Lorenz was amazed by what his goslings failed to distinguish:
Konrad Lorenz: “The human imprinted gosling will unequivocally refuse to follow a goose instead of a human, but it will not differentiate between a petite, slender young girl and a big old man with a beard. … It is astounding that a bird reared by, and imprinted to, a human being should direct its behavior patterns not towards one human but towards the species Homo sapiens.”[28]
18
Harry Harlow,
19
Jane van Lawick-Goodall, ‘The behavior of Free-living Chimpanzees in the Gombe Stream Reserve,’ Anim. Behav. Monogr. I: 161-311, 1968
20
In 1973, Konrad Lorenz and Nikolaas Tinbergen shared a Nobel Prize for these and other discoveries.
21
There also is some evidence that imprinting resembles addiction. For example, Jaak Panksepp’s [1988] experiments suggest that separation-distress may be similar to pain, because it is relieved by opiods. Howard Hoffman [1994] speculates that an object can become an Imprimer when certain aspects of its motion or shape arouse an innate mechanism that releases endorphins in the imprintee’s brain, and he conjectures that the resulting feelings of pleasure or comfort then somehow cause the object to be classified as ‘familiar’ enough to overcome other fearful reactions. In §9-x-Pleasure I’ll suggest that such feelings may play a somewhat less direct role.
24
[See Chapter 4 of
25
For example, see Charles A. Nelson’s article at http://www.biac.duke.edu/education/courses/spring03/cogdev/readings/C.A.%20Nelson%20(2001).pdf
26
Francesca Acerra, Yves Burnod and Scania de Schonen, http://www.dice.ucl.ac.be/Proceedings/esann/esannpdf/es1999-22.pdf
27
Meltzoff and Moore (1977) appear to have shown that infants can imitate lip protrusion, mouth opening, tongue protrusion, and finger movement. See http://ilabs.washington.edu/meltzoff/pdf/97Meltzoff_Moore_FacialImit.pdf