Early Learning and Imprinting
Last revised April 18, 2017.
Learning Before Birth
- Learning can happen before birth. Joe Hutto2 lived in the Wind River Mountains of Wyoming, where he got to know mule deer. Over the course of seven years, Hutto habituated them to his presence and was able to integrate himself into their society. Recognizing individuals allowed him to discern family relationships and to observe how the deer conducted their day-to-day lives. One doe who became pregnant happened to be very close to Hutto, and allowed him to follow her to where she would lie in her final weeks of her pregnancy. She even allowed him to lie down with her, put his head on her belly, and listen to her baby. He talked to the baby, and sang to it. Then, for several days, she was nowhere to be found. Hutto was worried. And then she appeared at his door. In the distance was an anxious youngster. Joe said hello to the little one who now came running forward. He had recognized Joe, not by sight but by sound. He knew that Joe must be OK. He had learned this when he was still in the womb.
- Learning before birth is not limited to mammals. We had a cockatiel named Freckles who we had hand-raised. Fifteen years later, Freckles had proved that he did not quite have the perfect parenting skills: he courted properly, and took his turn on the eggs. But when a baby hatched, Freckles did not know what to do about it. The baby would wander to the corner of the nestbox, where he would shiver and die, unattended and unfed. So after one clutch, I checked the nest box and rescued a little one on the day it was born. In an incubator on my desk, I talked to it, and watched it. We fed it many times every day. Finally, the little one — which we named “Bean” — could fly and was ready to return to his flock. I walked him upstairs and let him go. He flew directly to his Dad, and has scarcely left his side since. Bean had heard his parents talking in the nest box while he was still in the egg. He had learned their sound, and never forgot it. A month after his birth, he knew his Dad by sound, could pick him out of a crowd of cockatiels by sound, and could fly directly to him.
- Learning before birth is not limited to mammals and birds. We are thrilled by the mystery of sea turtles, who somehow return to the place of their birth to give birth themselves, several years later. No one seems to understand how they can do this. Surely their beach does not have a distinctive scent, or distinctive “look” from the sea. So how could they show up where they were born? I think I have the answer.
We built our house in the woods. One day I looked up our new driveway, and there was a huge turtle sitting there, staring at the house. I walked her to the side of the house, so she could continue down the hill to the river, and half an hour later, she was back in the driveway, staring at the house. Unlike my car’s GPS, which is happy to reroute me when I make a mistake, this turtle must have returned to a magnetic meridian that she used to guide her travel between pond and river. From her size, she might have been 30 years old, and had certainly made this trip between pond and river many times.
On another day, a big snake came down the driveway, tracing the turtle’s route. Our house was again in the way, but Mrs. Snake dealt with the issue with less evident confusion. She spent the night in the brush near our front door, and the next day continued on to the river — I could tell from the sound of the Blue Jays down near the river just where she now was. She apparently used about the same route as Mrs. Turtle, and was also making a semi-annual commute between pond to river.
On another day, I needed to go out the front door, and swung it open. A big turtle fell in. She had been standing on her back legs, struggling to get in through the glass. I don’t think she was the same turtle I’d previously seen, so this commuter route was starting to look like it once handled a lot of traffic.
So I thought I’d figured out the commuter route for these reptiles. But what happened next left me amazed. One day I stepped out onto the front porch to find a walnut up against the house. No, not a walnut. A tiny turtle, who’d flipped over on his back trying to get into the house. This little guy must have been born just a month or two earlier. He must have been born on the bank of the pond, and must be headed down to the river. As I thought about it, I realized that he had made this trip before: inside an egg, inside mom, he must have taken the trip from river to pond. On the trip, in the darkness of his eggshell, he must have sensed the critical magnetic meridian, and memorized it. Now he could do it all by himself. We think of turtles as not teaching their young anything, but this critical information was something that he must have learned from mom.
And so that could explain how a turtle hatched on a beach in the ocean could possibly figure out how to get back there when it was an adult: it could memorize while in the egg, either before or after the egg was laid.
What do turtles, snakes, and mule deer have to do with horses? Plenty. Youngsters have much to learn. A horse won’t wait for your trainer to arrive. He’ll need to get started earlier than that. And so a foal that is about to be born likely has a good idea of who he is. He likely knows one or two human voices, knows his mom’s voice, knows the voices of some of the others in the pasture.
Learning at the moment of birth: Filial Imprinting
“Imprinting” is a word that is often heard, and is used by laymen very casually to describe some connection that has formed between two animals. The popular horse literature is full of references to imprinting, and the value of imprinting foals on humans.
Imprinting may be defined as the process in which a very young animal bonds with some other animal or thing. The term was first used to describe chicks who, at birth, quickly learned to follow their mothers on land and in the water. A similar attachment could be made if chicks were hatched in an incubator, and then provided with a box on a moving toy train, or a caretaker, to follow. The imprinting seemed to favor the first large moving object encountered. Konrad Lorenz used the term Prägung to describe what had happened, and this word translates to “imprinting.3”
Imprinting can certainly give a bird two identities. Our hand-raised birds seem to view themselves as birds most of the time, but some of them are very comfortable at times being a person. Stewball, for instance, is now sitting on my knee, grooming his feathers. Soon I will be going downstairs to watch TV. He’ll likely choose to come with me, and watch TV with us until his biological clock tells him it is bedtime. Then he’ll say the word that means “I need to go up.” We’ll take him back to his room, where he will spend the night with 6 other birds, including his wife. When I take him back upstairs to their room, he may make a kissing sound as he gets closer — an indication he is fantasizing about being with his wife. But then, as he flies from my shoulder to her, he switches to the cockatiel word for love. For this word, at least, Stewball is bilingual.
Early research focused on the following reaction of precocial birds (their eagerness to follow mom or the first moving animal they meet early in life), something that is now called filial imprinting. Filial imprinting is useful in fostering a mother-offspring bond, and makes perfect sense. Even if a bird could learn to follow a man in boots or follow a toy train, in nearly every case the big moving thing nearby is mom, and learning to follow her is a key to survival. We can be comfortable believing that such a feat did not originate with birds, but that young dinosaurs of many species might have also followed their moms.
The idea of sexual imprinting soon developed, as cases were reported in which a chick raised by foster parents might show sexual attraction as an adult to the species that had done the rearing. Sexual imprinting seems to be possible throughout the world of birds. Klaus Immelmann4 reviews literature that finds:
- Sexual imprinting can occur when the eggs of one species are hatched and raised by foster parents of another species5.
- An individual bird of one color that is reared by foster parents of the same species but a different color will prefer to later pair with another of the foster parent color. This has been found in ducks, domestic fowl, domestic and feral pigeons, zebra finches, and Bengalese finches.
- Sexual imprinting can occur when humans are the chick’s foster parent, and for 25 species ranging from herons, storks, and owls to crows and meadowlarks, a chick fostered by a human may choose a human to pair and mate with.6
Filial imprinting seems to have been found in every species of bird that has been studied. We are all familiar with pictures of ducklings following a human or a dog that they have imprinted on. Whether filial imprinting occurs in other species is an open question. While there is a huge amount of early learning in mammals, it is not clear that any of this learning should be called “imprinting.” While the general public is comfortable with the word “imprinting” when talking about young mammals such as foals, scientists don’t use the term. Scientists don’t use the term “imprinting” when discussing mammals because mammals don’t imprint the way birds do.
Making Stuff Up
But there is nothing in science that prevents horse experts from making stuff up. A book Imprint Training of the Newborn Foal has been heavily promoted by its author, and has apparently been widely read. It won the 2012 Western Horseman Award, and happens to be published by Western Horseman, where the author happens to be a contributing editor of Western Horseman. Never shy about self-promotion, Miller writes about himself “Recognized internationally as one of the foremost authorities on equine behavior, Dr. Robert M. Miller has been named the recipient of the 2012 Western Horseman Award… The subsequent release of the book with the same title propelled Miller into the center of the emerging “Natural horsemanship” movement and made him one of the most sought out lecturers at veterinary schools, equine symposiums and clinics on equine behavior.7”
Miller’s book “Imprint Training” advocates for intensely, intimately handling newborn foals, pinning them down and doing this in very long sessions at birth, when it first stands, and when it first walks.
Clinton Anderson seems to advocate equally rough treatment of a foal in a video.8 Of course we should listen to Anderson, because (according to him), “Clinton and Downunder horsemanship are recognized as world leaders in the equestrian industry and continue to offer the very best in innovation, inspiration and instruction.”
The techniques proposed by Miller and Anderson do not seem to have anything to do with imprinting, however, but rather with roughing up the newborn. Human parents don’t manhandle their newborn babies. Mother ducks don’t manhandle their ducklings during imprinting. They care for them. The baby figures who to love and follow.
In fact, a number of studies conclude that the “imprinting” efforts as advocated by Miller and Anderson do not work, and are not a good idea.
- A study of an imprint training procedure conducted at birth on the reactivity of foals at age 1, 2 and 3 months indicated that the procedure failed to result in a significant difference in the reactivity of trained foals, as measured by changes in heart rate, time needed to complete tasks and foal behavior.9
- Williams and others studied 131 foals and divided them into different treatment groups: no imprint training, imprint training four times (at birth, 12, 24 and 48 h after birth), or imprint training once (at birth, 12, 24, 48, or 72 h after birth). Foals then received minimal human handling until they were tested at 6 months. The researchers concluded that neither the number of imprint training sessions (0, 1, or 4) nor the timing of imprint training sessions (none, birth, 12, 24, 48, or 72 h after birth) influenced the foal’s behavior at 6 months of age.10 In this study, imprint training did not result in better behaved, less reactive foals.
- Hausberger and others studied 21 breeding farms and 170 horses in France, finding that those with easy and calm yearlings and young horses were farms where handling occurs mainly around weaning and/or in the following year, whereas farms with fearful young horses were characterized by either very intensive and permanent handling (from imprinting to daily halter fitting, handling, leading etc.) or by no handling at all after weaning and the following year. To produce a calm horse, the best approach seems to be moderation in the handling of foals.11
A foal is nearly helpless. Clinton Anderson recommends that it be pinned down by one person, so that another can rough it up. He says “If the hindquarters is not under control, it is easy for the foal to rear up, flip on his back, and bolt away from you.12” Any treatment that would make a foal want to do this is not a treatment that will make the foal love you. It is a big step toward Learned Helplessness.
It is wrong to talk about imprinting in horses. Mammals do not show filial imprinting like birds, and don’t show sexual imprinting like birds.13 Horses don’t imprint.
But early exposure, early learning is important in all animals, including horses.
Familiarity and Comfort: Another Means of Learning to Recognize Kin
We know that kin recognition occurs throughout the animal kingdom, including single-celled organisms. There does not seem to be a general theory of how this happens, so I’m free to offer my personal views here. First, it seems unlikely that each species developed its own means of deciding who is kin. So we need to consider a thread that could run through the entire animal kingdom. Such a thread could be that of familiarity.
- All organisms have had some experience with themselves. If they have a sense of smell, then their own odor is surely familiar. Many animals have hearing, and can make sounds; such sounds will be familiar.
- Repeated exposure breeds familiarity, and familiarity breeds comfort. Individuals are drawn to those that are comforting. In the course of doing this, comfort breeds greater familiarity, strengthening the bond between individuals.
- The more another individual smells or sounds or looks like us, the more likely they are to be kin. But in many species, kin recognition could simply be an artifact of familiarity.
Familiarity could account for both “normal” kin recognition (that is, a wolf raised by wolves) and “abnormal” kin recognition (a child raised by wolves). But it doesn’t account for kin recognition in animals that don’t have the degree of parenting offered by birds, mammals, alligators, and some fish.
How does familiarity breed comfort? It might be because familiarity lowers plasma corticosterone levels which underlie stress.14 It may be that familiarity shapes the effects of oxytocin, making us want to associate with and protect those we are familiar with, and be more violent or aggressive to those we are not familiar with. Whatever the mechanism, it seems likely that hormone levels play some role.
An instinct is an unlearned fixed action patten that is triggered by some stimulus. In his fabulous book “Illumination in the Flatwoods: A season with the wild turkey”, Joe Hutto15 describes how very young turkeys walking through the woods were able to behave differently toward poisonous and non-poisonous snakes on their first encounters. Because his turkeys had never been out of his sight, Hutto could be sure that these encounters were their first. It seemed clear to me that some clues to species identification were buried in these turkey’s brains at birth, and guided their reactions appropriately.
Instinct might explain how turtles choose partners. Turtles have almost no contact between parent and progeny. Dad inseminates mom and leaves. Mom lays eggs and leaves. The only real contact is while junior is in the egg, inside mom. But turtles don’t hang out in schools or flocks. They live solitary lives, and are found together only when something of common interest has drawn them, such as a feeding station on a dock in the river. Instinct, rather than acquired familiarity, must explain turtle choice of partners. But just exactly how this works is a mystery — at least to me.
Other reptiles, though, get more nurturing in childhood. Mrs. Alligator, for instance, carefully builds a nest, guards the nest from predators, and as the babies hatch, helps them get out of their shells. She carries them to nearby water in her mouth, and protects them for a year or more. For mama alligator, some mix of instinct and childhood experience may be crucial to her success as a mother.
In Hutto’s study of young wild turkeys, he observed that they showed amazement and concern when they came upon the aging stump of a tree that had been dropped by a chain saw. Such a stump takes an unnatural shape — one that we are very accustomed to, but that a young turkey would have never seen. Because these turkeys showed no such initial reaction to a naturally formed stump which was created when a tree died and fell, Hutto suspected that the turkeys had an inborn expectation of what a stump should look like. My mule Bud must have gone to turkey school, because he showed the same reaction to a cut stump when he first saw one. As with the turkeys, it was only the old chain sawed stump that alarmed him. All of the naturally formed stumps that he had encountered in these early days caused no alarm at all. How can an image of a healthy stump be stored and passed on to offspring, so that a turkey or a mule will know that a sawed stump is unusual?
Instincts can guide our expectations (stumps), our object identifications and reactions (to poisonous snakes), our preferences in a mate (turtles) and surely much more. As a research topic, instinct is no longer in fashion, having been taken over by psychoanalysts. But when my mule and a wild turkey have the same reaction to the work of a chain saw, I’m left yearning for more science, and more understanding. Because early learning and familiarity can come to mask an instinct, our observations must be very careful and thorough, and be done very early to see instincts at all.
People who have the chance to work with foals will often make a claim that they spend time with them so that they will imprint on humans. Certainly spending time with a foal gives them a good head start in understanding and accepting the ways of the bipedal world.
Familiarity seems like a perfectly useful explanation of how a foal might learn to recognize his kin. And there are a number of studies that suggest that early exposure to humans might be good for foals. In one experiment,16 lamb twins were used to determine the effect of exposure to humans. Lambs were fed milk replacer and handled four times a day for five minute periods at the ages of 1-3, 3-5, 5-7, or 7-9 days. Those lambs that received this 40 minutes of human contact at the age of 1-3 days were less timid and more willing to make contact with a human than those exposed later in life or their twins, who were not exposed. But even if we are willing to extrapolate from lambs to horse foals, we should not extrapolate from 1-3 days to 1-3 years. Early contact seems to be far more important in building comfort with human contact.
By the definition used by scientists, there is a sensitive period that is critical for imprinting: During this period, the youngster is best able to learn who it is, and who it should follow. As this period of greatest sensitivity comes to an end, exposure produces weaker learning, weaker tendencies to follow. The abruptness of the end of the sensitive period may depend on the species. But in the studies which use the term “filial imprinting”, the critical period is a matter of hours or days, not weeks or months.
This is not to say that later contact with an animal is without benefit. Handling birds and mammals under positive circumstances can alleviate animal stress in the presence of people, decreasing its impact on animal health17, fecundity18, productivity19 and welfare20. In chickens, daily habituation to non-threatening people increases egg production21 and allows them to gain weight faster with less feed.22 Gently stroking pigs whenever they approach people, increases approaches towards people, growth rate and feed-conversion efficiency23. Food rewards and gentle handling decrease the heart rate, adrenal response and flight distance of sheep in the presence of people24.
Williams et al25 review this literature: Foals which received handling sessions that lasted varying periods from one week to 18 months, beginning at weaning, learned more quickly and had fewer errors on a learning task than foals that did not receive any handling. Foals that received more handling learned the quickest and had fewer errors than those foals that received less handling;26 Williams et. al. also cite a study finding that foals handled 5 days/week beginning 24 h after birth and ending 42 days after birth were trained to lead more quickly than those handled beginning at 42 days and lasting until 84 days after birth.
We should assume that at all ages, increased familiarity with people will improve a horse’s comfort with them, and in turn, will improve their well-being. So spend some quality time with your horse!
1 Image source: https://pixabay.com/p-1465631/?no_redirect
2 This is the most remarkable book you may read this year: Hutto, J. Touching the Wild: Living with the Mule Deer of Deadman Gulch 1st Edition Skyhorse Publishing. April 1, 2014 320 pp
3 Prägung also translates as “coining”, “stamping”, and “engraving”.
4 Immelmann, K. (1972). Sexual and other long-term aspects of imprinting in birds and other species. Advances in the Study of Behavior, 4, 147-174.
5 Immelmann, K. (1972). Sexual and other long-term aspects of imprinting in birds and other species. Advances in the Study of Behavior, 4, 147-174.
6 Klinghammer, E. 1967. Factors influencing choice of mate in altricial birds. In “Early Behavior: Comparative and Developmental Approaches” (H. W. Stevenson, ed.), pp. 5-42, Wiley, New York.
7 Miller, R.M. “Western Horseman Magazine names Dr. Miller ‘2012 Western Horseman Award Honoree’” http://www.robertmmiller.com/20wehoofye.html
8 DUHorseman “Foal Training: Touch and Rub” https://www.youtube.com/watch?v=N4A8rCZZFfU
9 Williams, J.L., Friend, T.H., Toscano, M.J., Collins, M.N., Sisto-Burt, A. and Nevill, C.H. (2002) The effect of early training sessions on the reactions of foals at 1, 2 and 3 months of age. Appl. anim. behav. Sci. 77, 105-114.
10 Williams, J. L., Friend, T. H., Collins, M. N., Toscano, M. J., Sisto-Burt, A., & Nevill, C. H. (2003). Effects of imprint training procedure at birth on the reactions of foals at age six months. Equine veterinary journal, 35(2), 127-132.
11 Hausberger, M., Henry, S., Richard, M.-A., 2004a. Expériences précoces et développement du comportement chez le poulain. In : Compte-rendu de la 30ème Journée de la Recherche Equine, 3 mars 2004, Paris, pp. 155-164
12 DUHorseman “Foal Training: Touch and Rub” https://www.youtube.com/watch?v=N4A8rCZZFfU
13 In contrast to the willingness of birds to engage in sexual imprinting, and the willingness of researchers to study it, sexual imprinting has scarcely been examined in mammals, perhaps because it does not occur. One study found that mice raised by a different subspecies of mouse seemed to prefer that different subspecies as partners when mating. There have been many reports of males of various species of mammals trying to mate with things outside their species — a dog under the dining table mating with your leg, for instance — but all of these stories derive from lust and confusion, rather than imprinting. G once mounted his Parelli ball while we were playing with it, but he never met a Parelli ball until he was 8, and had not imprinted on it.
14 Barnett, J. L., Hemsworth, P. H., Hennessy, D. P., McCallum, T. H. & Newman, E. A. 1994. The effects of modifying the amount of human contact on behavioral, physiological and production responses of laying hens. Appl. Anim. Behav. Sci., 41, 87–100.
15 Hutto, J. (2006). Illumination in the Flatwoods: A season with the wild turkey. Globe Pequo
16 Markowitz, T. M., Dally, M. R., Gursky, K., & Price, E. O. (1998). Early handling increases lamb affinity for humans. Animal Behaviour, 55(3), 573-587.
17 Maier, S. F., Watkins, L. R. & Fleshner, M. 1994. Psychoneuroimmunology: the interface between behaviour,brain, and immunity. Am. Psychol., 1004–1017.
18 Hemsworth, P. H., Barnett, J. L. & Hansen, C. 1986a. The influence of handling by humans on the behaviour, reproduction and corticosteroids of male and female pigs. Appl. Anim. Behav. Sci., 15, 303–314.
19 Seabrook, M. F. 1972. A study to determine the influence of the herdsman’s personality on milk yield. J. Agric. Labour Sci., 1, 44–59; Apple, J. K., Unruh, J. A., Minton, J. E. & Bertlett, J. L. 1993. Influence of repeated restraint and isolation stress and electrolyte administration on carcass quality and muscle electrolyte content in sheep. Meat Sci., 35, 191–203.
20 Dawkins, M. S. 1980. Animal Suffering: The Science of Animal Welfare. London: Chapman & Hall.
21 Barnett, J. L., Hemsworth, P. H., Hennessy, D. P., McCallum, T. H. & Newman, E. A. 1994. The effects of modifying the amount of human contact on behavioral, physiological and production responses of laying hens. Appl. Anim. Behav. Sci., 41, 87–100.
22 Hemsworth, P. H., Coleman, G. J., Barnett, J. L. & Jones, R. B. 1994. Behavioural responses to humans and the productivity of broiler chickens. Appl. Anim. Behav. Sci., 41, 101–114.
23 Hemsworth, P. H. & Barnett, J. L. 1991. The effects of aversively handling pigs, either individually or in groups, on their behaviour, growth, and corticosteroids. Appl. Anim. Behav. Sci., 30, 61–72.
24 Hutson, G. D. 1985. The influence of barley food rewards on sheep movement through a handling system. Appl. Anim. Behav. Sci., 14, 263–273.
25 Williams, J. L., Friend, T. H., Collins, M. N., Toscano, M. J., Sisto-Burt, A., & Nevill, C. H. (2003). Op cit.
26 Heird, J.C., Whitaker, D.D., Bell, R.W., Ramsey, C.B. and Lokey, C.E. (1986) The effects of handling at different ages on the subsequent learning ability of 2-yearold horses. Appl. anim. behav. Sci. 15, 15-25.