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Harlow's experiment and maternal deprivation: replacing the mother

Harlow's experiment and maternal deprivation: replacing the mother

May 6, 2021

When talking about psychology, many people may think of personality traits, mental disorders or cognitive biases. In short, elements that we can relate to a single person: each one has their level of intelligence, the presence or absence of a diagnosed disorder, or a propensity to fall into certain deceptions of the mind. However, there is a subject that is also very approached by psychology: the way in which interpersonal relationships change us.

The paradigms prevailing in the first half of the twentieth century in psychology, which were the psychodynamics born with Sigmund Freud and the behaviorism defended by BF Skinner, supported the idea that the foundation of affection between mothers and their young sons and daughters is feeding and, more specifically, breastfeeding. In their way, each of these two psychological currents so different from each other in most of their approaches proposed the same idea: that babies and mothers began to engage in affective behaviors thanks to the need of the first to be fed. Right after birth, the mothers' main role was to provide food for their offspring.


However, psychologists John Bowlby and, later, Harry Harlow, dealt a severe blow to this theory. It is thanks to them that today we know that affection in its purest and most literal sense is a fundamental need of children. Specifically, Harry Harlow's monkey experiment on maternal deprivation is an example of this.

The precedent: Bowlby and the theory of attachment

In the middle of the 20th century, an English psychiatrist and psychologist called John Bowlby He conducted a series of investigations framed in what is known as attachment theory. This is a framework of debate in which the psychological phenomena that are behind our way of establishing emotional ties with other beings are explored, and in it the way in which fathers and mothers relate to their babies during a period of time is particularly important. the first months of the latter's life.


The reason for this interest in the early stages of link formation is simple: it is assumed that the way in which the small close continued relationships , close and with signs of affection with others will influence their development towards adulthood and will have an impact, possibly for life, on several of their psychological characteristics.

The investigations of Bowlby

Through several studies, John Bowlby concluded that the fact that each baby regularly disposes of maternal affection is one of the most important needs in the face of its correct growth.

In part, this was based on their beliefs: Bowlby adopted an evolutionary approach, and defended the idea that both mothers and newborns express specially selected genes to make both of them form a strong emotional bond. That is, he believed that the establishment of maternal attachment was genetically programmed, or at least a part of it. In addition, he argued that the strongest bond that every person can get to establish is based on the relationship he had with his mother during the first years of life.


This phenomenon, which he called monotropy, it was not possible to consolidate if this exchange of affectionate gestures accompanied by physical contact (classically, during feeding during lactation) occurred once the second year of the baby's life had been completed, and not before. That is, that the maternal deprivation, the absence of regular contact with a mother who provided affection during the first months of life, was very harmful to go against what our genetics would have programmed us for.

What did these studies consist of?

Bowlby also relied on empirical data . In this sense, he found some data that reinforced his theory. For example, through an investigation commissioned by the World Health Organization about children separated from their families by the Second World War, Bowlby found significant evidence that young people who had experienced maternal deprivation because they lived in Orphanages tended to present intellectual retardation and problems to successfully manage both their emotions and the situations in which they had to relate to other people.

In a similar investigation, she observed that among the children who had been incarcerated for several months in a sanatorium to treat their tuberculosis before reaching the age of 4, they had a markedly passive attitude and rode in anger much more easily than the rest of young people.

From that point, Bowlby continued to find data that reinforced his theory.He concluded that maternal deprivation tended to generate in young people a clinical picture characterized by emotional detachment towards other people. People who had not been able to form a bond of intimate attachment with their mothers during their early years were unable to empathize with others, because they had not had the opportunity to connect emotionally with someone during the stage in which they had been sensitive to this type of learning .

Harry Harlow and the experiment with Rhesus monkeys

Harry Harlow was an American psychologist who, during the 1960s, set out to study Bowlby's theory of attachment and maternal deprivation in the laboratory. For this, he conducted an experiment with Rhesus monkeys that under current ethical standards would be unrealizable by the cruelty involved.

What Harlow did was, basically, Separate some baby monkeys from their mothers and observe how their maternal deprivation was expressed . But he did not limit himself to observing passively, but introduced in this research an element with which it would be easier to know what the macaque pups felt. This element was the dilemma of choosing between something similar to physical contact related to affection and warmth, or food.

Substituting the mother

Harlow introduced these pups inside cages, space that they had to share with two artifacts. One of them was a wire structure with a full bottle incorporated, and the other was a figure similar to an adult macaque, coated with soft plush, but no bottle . Both objects, in their own way, pretended to be a mother, although the nature of what they could offer the baby was very different.

In this way, Harlow wanted to test not only Bowlby's ideas, but also a different hypothesis: that of conditional love. According to the latter, the offspring relate to their mothers basically for the food they provide, which objectively is the most useful resource in the short term from a rational and "economistic" perspective.

What was discovered

The result proved Bowlby right. The pups showed a clear tendency to cling to the plush doll, despite not providing food. The attachment to this object was much more noticeable than the one they professed towards the structure with the bottle, which was in favor of the idea that it is the intimate bond between mothers and babies that is really important, and not just food.

In fact, this relationship was evident even in the way the offspring explored the environment. The plush doll seemed to provide a feeling of security that was decisive for the small macaques decided to undertake certain tasks on their own initiative and even embraced more strongly when they were afraid. In the moments in which some change was introduced in the environment that generated stress, the young ran to embrace the soft doll. And, when the animals were separated from this plush artifact, they showed signs of desperation and fear, screaming and searching all the time for the protective figure. When the plush doll was returned to their reach, they recovered, although they remained on the defensive in case they lost sight of this artificial mother again.

Causing isolation in monkeys

The experiment of the plush doll and bottle was of doubtful morality, but, Harlow went further by worsening the living conditions of some macaques. He did so by confining pups of this animal species in closed spaces, keeping them isolated from any kind of social stimulus or, in general, sensory.

In these isolation cages there was only one drinking trough, a feeder, which was a total deconstruction of the concept of "mother" according to behaviorists and Freudians. In addition, in this space a mirror had been incorporated thanks to which one could see what the macaque was doing but the macaque could not see its observers. Some of these monkeys remained in this sensory isolation for a month, while others stayed in their cage for several months; some, up to a year.

The monkeys exposed to this type of experiences already had evident alterations in their way of behaving after having spent 30 days in the cage, but those who stayed a full year were in a state of total passivity (related to catatonia) and indifference towards the others who did not recover. The great majority ended up developing problems of sociability and attachment when they reached the adult stage, they were not interested in finding a partner or having offspring, some did not even eat and ended up dying.

Negligent mothers ... or worse yet

When Harry Harlow decided to study the maternal behavior of the macaques to which he had been subjected to isolation, he found the problem that these female monkeys did not get pregnant. For this he used a structure ("the colt of rapes") in which the females were fixed with straps, forcing them to be fertilized.

Subsequent observations showed that these females not only did not perform the typical tasks of a mother of their species, ignoring their young for most of the time, but sometimes even mutilated their offspring. All this, in principle, because of maternal deprivation, but also because of social isolation, during the first months of life.

Conclusions: the importance of attachment

Both John Bowlby's research and Harry Harlow's experiments are very much taken into account today, although the latter are also a case of clear torture towards animals, and because of its ethical implications have received strong criticism .

Both experiences led to similar ideas: the effects of the absence of social interactions that go beyond the most immediate biological needs and that are linked to affective behavior during the first stages of life tend to leave a very serious and difficult footprint. erase in adult life.


Harlow's Monkeys (May 2021).


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