The Domesticated Brain: A Pelican Introduction (Pelican Books)

According to available records, the youngest child convicted and executed for a crime in England was John Dean, aged around eight years. He was hanged in Abingdon for setting fire to two barns in the nearby town of Windsor in 1629. At the time, the age of criminal responsibility was seven years, at which point children were considered to be little adults. Indeed, this is how they were often portrayed in paintings from that period.

In Van Dyck’s (1637) portrait of the children of Charles I, they look like miniature adults. Charles II, the boy in the painting, is only seven years old, yet he is shown with the posture of an adult, with feet crossed in a casual lean against the wall. The portrait reflects the prevailing attitude of the time that children simply lacked the wisdom of experience and that with training they would become acceptable to society. Like empty vessels, they needed to be filled up with information and instructed how to behave.

John Locke (1632–1704), the English philosopher, captured this view of the child as a blank canvas:

Let us then suppose the mind to be, as we say, white paper void of all characters without any ideas. How comes it to be furnished? Whence comes it by the vast store which the busy and boundless fancy of man has painted on it with an almost endless variety? Whence has it all the materials of reason and knowledge? To this I answer, in one word, from EXPERIENCE.¹

Figure 1: Children depicted as ‘Little Adults’

Locke described the infant’s mind as a ‘tabula rasa’ or blank slate. Not only was the infant’s mind considered empty, it was one that was faced with the daunting task of making sense of a complex and confusing new world of sensations and experience that the American psychologist William James would later describe in 1890 as a ‘blooming, buzzing confusion’.²

However, Locke’s blank slate view is not plausible, nor is the newborn’s world completely confusing as James imagined. As the Prussian philosopher Immanuel Kant³ (1724–1804) pointed out, blank slates would not work unless they were already set up to detect the structures of the world. There has to be some organization built in in order to determine what constitutes a pattern in the first place. Consider how complicated vision would be without some pre-existing knowledge. You cannot begin to understand the world around you unless you have some inkling of what you are looking for. In order to perceive the world, you need to distinguish objects from backgrounds and determine where one object begins and another ends. We rarely consider these as problems because vision is so effortless. It is only when you try to build a machine that can see that the difficulty becomes all too obvious.

In 1966, Marvin Minsky, one of the pioneers of artificial intelligence, is said to have asked one of his undergraduate students at MIT to ‘spend the summer linking a camera to a computer and getting the computer to describe what it saw’. Presumably Minsky thought that the problem was easy enough that it should take the duration of a summer vacation for a student to solve. That was almost fifty years ago and thousands of professional scientists are still working on how to make machines see like humans.

Back in the 1960s, artificial intelligence was a new field of science that promised us a labour-saving future where robots clean the house, wash the dishes and basically perform all the mundane chores humans hate to do. Since then we have witnessed remarkable developments in computing and technology and there are certainly very smart vacuum cleaners and dishwashers. But we still have not been able to build a robot that perceives the world like a human. They may look human but they are unable to solve some of the simplest problems we take for granted, ones that most babies master before their first birthday.

Another reason why the blank slate cannot be true is because it turns out to be physiologically wrong. Our senses are pre-configured in anticipation of the sorts of signals that we can expect as babies. We do not have to learn to distinguish different colours, or that a boundary between brightness and darkness corresponds to an edge. If you measure from brain cells that react to sensation in unborn animals before they have had any experience of the external world, they will already respond to features that they have not yet encountered.Human newborns will show immediate preferences for some patterns before they have had any time to learn them, so their world is not totally confusing. These early capabilities show that there is considerable formatting in the newborn’s brain that enables them to make sense of experiences.

Figure 2: Spot the difference

Like a computer that you buy from a store, the brain already comes with an operating system installed. What you eventually store on it really comes down to what you do with it. Biology and experience work together to generate a developing mind, adapted to the external world. That process is one of discovery as each child goes about decoding the complexity of the world around them by using the tools that evolution has bestowed upon them.

Getting wired up

The brain of any animal is as complex as it needs to be to solve the world problems that the creature has evolved to accomplish. In other words, the more versatile an animal’s behaviour, the more sophisticated their brain.⁴ This versatility comes from the capacity to learn – storing memories as patterns of electrical connectivity in the specialized brain cells that alter in response to experiences. In the human adult, the brain is comprised of an estimated 170 billion cells, of which 86 billion are neurons.⁵ The neuron is the basic building block of the brain’s communication processes that support thoughts and actions.

Each neuron looks like a many-tentacled creature from outer space with a body from which branch thousands of receptors or dendrites that receive incoming signals from other neurons. When the sum of incoming nerve impulses reaches a critical threshold, the receiving neuron then discharges its own impulse down the axon to set off another chain reaction of communication. In this way, each neuron acts like a miniature microprocessor. The patterns of nerve impulses that spread across the vast network of trillions of neural connections are the language of the brain as information is received, processed, transmitted and stored in these networks. The presentations of experiences become re-presented, or representations – neural patterns that reflect experiences and the internal computing processes our brains perform when interpreting information.

One of the more surprising discoveries about brain development is that human infants are born with almost the full complement of neurons that they will have as an adult. Yet the newborn brain weighs about a third of the adult brain. Within a year, it is about three-quarters the size of the adult brain.⁶ Connections form at a rate of 40,000 per second in the newborn, which is over 3 billion per day.⁷ Eventually, the length connecting fibres will extend to an estimated 150–180,000 km – enough wiring within an individual human brain to circumnavigate the world’s equator four times.⁸ In fact, the bulk of the brain is mostly connections, with the neurons squeezed into 3–4mm of the outer layer that covers the surface of the brain, called the cortex after the Latin word for ‘bark’.

These changes in connectivity enable the world to shape the brain by experience because experience keeps the neurons active through repeated mutual activation. This shaping process is called plasticity after the Greek word plassein, meaning ‘to mould’. Synapses between cells that are in constant communication change in their sensitivity so that messages transfer more easily between them. At its most basic level, this is how information is stored in the brain – as changing patterns of neuronal activity. This crucial role for reciprocal neuronal activity is captured in the first of the neuroscientist’s principles of plasticity, ‘cells that fire together, wire together’.⁹

Most brain plasticity occurs during child development, with some areas continuing to change well into the late teenage years. The front part of the brain, associated with decision-making, does not become fully mature until the child reaches adulthood. Of course, there is plasticity in the adult brain as we constantly learn throughout our lifetime. However, connectivity in some brain systems seems to be time sensitive, requiring input much earlier in development. Remember neural activity is metabolically expensive. If neural connections are not active, then why keep them? In many ways it is similar to pruning your favourite rose bush. You cut away the weaker branches in order to allow the stronger branches to flourish.

These windows of opportunity, which are sometimes called critical periods, reflect the way that Nature has produced a brain that anticipates specific experiences at certain times; if these are denied or impoverished, there may be long-term impairment. This is true for the sensory systems such as vision and hearing, but as we will read in the next chapter, there appear to be critical periods for social skills as well. This loss of function due to deprivation is a second principle of plasticity, where you have to ‘use it or lose it’ when it comes to keeping neural mechanisms functional.

Core knowledge

In the same way that our brain is pre-configured to experiences before we have even had the chance to encounter the relevant sensations, some scientists believe that we are also wired to interpret the world in particular ways before we have had the chance to think about it. The speed at which babies acquire and understand aspects of the world around them before they are capable of comprehending spoken language indicates that they must be working things out fofigr themselves. As adults, we take it for granted that the world is made up of objects, spaces, dimensions, plants, animals and all manner of complex ideas that we rarely take the time to consider because we have had a lifetime of exposure to them. But how do young babies come to appreciate these concepts in the absence of language? When a baby looks around its new blurry world, what does it make of it all? Even if they are learning by themselves, how do they know what to pay attention to and what is relevant? These sorts of problems have led to the proposal that some key components of understanding the world, especially those related to the physical nature of objects, numbers and space, must be programmed into the brains of infants from birth. But how do we know what babies are thinking when they are not even capable of telling us what is on their minds? The answer comes down to showing them magic tricks.

The reason that we find magic tricks so entertaining is that they violate our expectations. When a magician makes an object vanish into thin air, we are first surprised and then set about trying to figure out how they achieved the illusion. As adults, we know that a physical law has only apparently been violated because if we did not have that understanding, then we would not be surprised. That is why it is a trick. The same is true for babies. When they are shown magic sequences where objects appear to vanish, infants look longer. They do not applaud or gasp as an adult audience would, but they notice that something is not quite right.

This magic-trick technique, known as violation of expectancy, has spawned hundreds of experiments used to tap into the minds of infants who cannot tell us what they are thinking. Harvard psychologist Elizabeth Spelke has been using violation of expectancy to probe the rules infants apply when understanding the physical world.¹⁰ From very early on, infants recognize that solid objects do not pass through other solid objects, move from one position to another without appearing in between, move by themselves unless contacted and nor do they dissolve or fall apart when touched. When we say that something is ‘solid as a rock’, it is so because it obeys Spelke’s rules for physical objects. These rules do not have to be learned and for most objects that the child will encounter throughout the rest of their life, these principles will hold true, which is why they are referred to as core knowledge, because they are programmed into the mind from birth.

Of course, there are some exceptions to these rules, such as in the case of magnets, where an iron object will move in the absence of direct contact with another object. Soft bananas dipped in liquid nitrogen become hard as nails. These exceptions to the normal rules are enchanting because they violate our expectations of how physical objects should behave. Many toys that you find in science museums are counter-intuitive examples that amaze and amuse precisely because they do not behave like most ordinary objects.

It’s alive!

Babies appreciate that people are also another type of object, but one with a special set of properties. For a start, people can move by themselves. If an inanimate object is left behind a screen then it should still be there unless someone has moved it. A person, on the other hand, can leave the room when you are not looking, so may not necessarily remain stationary when they are out of sight.¹¹ Also people do not have to move in a straight line. Five-month-olds who watched a video of a box sliding across a stage and passing behind two screens were surprised if it did not reappear in the gap in between. However, they were not surprised when a person moving across the same stage did not reappear in between the screens, suggesting that the infants could draw a distinction between how a box and a person can behave when moving in between screens.

Living things also move in particular ways. Objects that are not alive tend to move in a rigid way, whereas living things have ‘biological motion’ which is much more fluid and flexible. These types of movement are processed by neurons that are tuned to directions and speed in the visual area at the back of the brain known as MT. Biological motion is less rigid and activates a different region which is closer to the area behind your ears that is activated by faces. This area, the fusiform gyrus, also registers the shape of the human body, which suggests it might be a region that stores general information about others like us.¹² When we think of others, we expect them to be a certain shape and move in a certain way. By six months of age, babies are surprised to see a female who appears to have arms growing out of her hips that swing as she walks.¹³

How do babies decide what is human? We know that babies like to look at other people. They prefer biological motion at birth.¹⁴ We also know they prefer the sound of the human voice and their mother’s voice in particular.¹⁵ They prefer the smell of their mother compared to the smell from another mother.¹⁶ Just about every capability of the newborn’s senses seems to be tuned into their mums.

Over time, infants gradually start paying attention to others and noticing what they are doing. When you think about it, the sheer volume of information contained in just a minute or two of a typical everyday action that an adult might perform is staggering.¹⁷ Consider the individual steps involved in making a cheese sandwich. Every sequence requires complex motor skills that must be performed in a way that is beyond the capabilities of robots. Ingredients and implements must be retrieved from various locations in the kitchen and then prepared and assembled in the correct pre-planned order. There is no point trying to butter the slice of bread after the cheese has been inserted. How do babies begin to make sense of what they see when watching others? It turns out that in just the same way that baby brains are wired to chop language up into different segments, they are programmed to observe and learn different actions. Infants as young as six months are sensitive to the statistical regularities in action sequences and by ten to twelve months readily segment complex actions up into their constituent parts based on the flow of movements as they start and stop.¹⁸

So babies are the consummate people persons – they love to watch others. People are the most interesting objects to babies not only because they look and move in a particular way in complex action sequences but because they interact with them. Synchrony is critically important to establishing social interactions and babies are on the lookout for those who are tuned into them. As adults, we instinctively engage in these synchronized activities, often mimicking the baby in an attempt to capture their affections. Two-month-old infants will even treat non-living objects that act contingently as if they are alive and smile at them.¹⁹ As they build up their models of what it is to be human, they are looking for evidence for those things that are most likely to be important for their survival and becoming increasingly more sophisticated in their decisions.

Thinking objects

Babies rely on faces, biological movement and contingent interaction to draw up a list of credentials that make something worth paying attention to. Any one of these attributes may signal that something is worth watching because they are starting to draw a distinction between the living and non-living world in terms of agency. Non-living things move because some force has acted upon them, whereas agents act independently for a purpose – they have goals. They have choices. When we understand that something has goals, we see it as intentional. We do this all the time with animals and our pets, when we give them human qualities using a cognitive bias called anthropomorphism, but we will even extend such ‘humanness’ to things that are clearly not alive, let alone possessed of minds.

Imagine three geometric shapes moving around a screen. A large triangle attacks a smaller triangle by banging into it and then corners a small circle inside a rectangular box. The circle moves around frantically inside the box as if trapped. The smaller triangle distracts the large triangle, allowing the circle to escape, and then closes the opening to the box, trapping the large triangle inside. The small triangle and circle rotate around each other in joy and then exit the screen. The large triangle proceeds to break up the box in a fit of rage. Hardly the script of a Hollywood blockbuster, but observers interpret this sequence as some sort of domestic dispute.²⁰

This simple animation made by psychologists Fritz Heider and Marianne Simmel in 1944 demonstrates that humans anthropomorphize moving shapes that appear to be goal directed and generate rich interpretations consistent with social relationships. The philosopher Dan Dennett thinks that we adopt an intentional stance as a strategy to first look out for things that could be agents that could have consequences for us and then give them intentions.²¹ When something has a face, moves as if alive or behaves in a purposeful way, we think that it has a mind that may have intentions directed towards us.

Attributing agency is something that babies also do from very early on. Based on the Heider and Simmel animation, infant psychologist Val Kuhlmeier showed infants a cartoon geometric red sphere, appearing to climb up a steep hill, that kept faltering and slipping down the slope.²² At one point, a green pyramid shape comes along and pushes the sphere up the slope until it reaches the top. To most of us, this seems to be a case where the pyramid has helped the sphere up the slope. In a second scene, the red sphere is again trying to climb up the hill but this time along comes a yellow cube that blocks the path and then pushes the sphere down the slope. The cube has hindered the sphere. Even though these are simple animations of geometric shapes, we readily see them as intentional agents. A sphere that wants to climb a hill, a pyramid that wants to help and a cube that wants to hinder.

Figure 3: Scene from Heider and Simmel 1944 animation

What is remarkable is that babies even as young as three months of age make exactly the same decisions about the different shapes.²³ They look longer when a shape that has always helped suddenly starts hindering. Already at this age they are attributing good and bad personality characteristics to the shapes.

Are you thinking what I am thinking?

We not only judge others by their deeds but we also try to imagine what is going on in their minds. How do we know what others are thinking? One way is to ask them, but sometimes you cannot use language. On a recent trip to Japan, where I do not speak the language, I discovered just how much I took communication for granted. But before language, there had to be a more primitive form of communication that enabled humans to begin to understand each other. We had to know that we could share ideas, something that requires an awareness that others have minds and an understanding of what they might be thinking. The real quantum leap in the history of mankind that transformed our species was not initially language, but rather our ability to mind read.

Mind reading

I am going to surprise you with a little mind reading. Take a moment to look over the picture below, Georges de la Tour’s famous painting ‘The Cheat with the Ace of Diamonds’ (1635), until you have worked out what is going on.

In all likelihood, your eyes were instinctively drawn to the lady card player at the centre of the picture and, from there, you probably followed her line of gaze to the waitress and then to the faces of the two other players. Eventually you will have spotted the deception. The player on the left is cheating, as we can see that he is taking an ace from behind his back to change his hand into an ace flush of diamonds. He waits for his moment when the other players are not paying attention to him.

How did I know where you would look? Did I read your mind? I did not need to. To fully understand de la Tour’s painting, you have to read the faces and the eyes to work out what is going on in the minds of the players. Studies of the eye movements of adults looking at pictures of individuals in social settings reveal a very consistent and predictable path of scrutiny that speaks volumes about the nature of human interactions.²⁴ Humans seek out meaning in social settings by reading others, whereas another animal wandering through the Louvre Museum in Paris where de la Tour’s masterpiece hangs would probably pay little attention to the painting let alone scrutinize the faces for meaning.

Figure 4: ‘The Cheat with the Ace of Diamonds’ by Georges de la Tour (1635)

How do we begin to mind read? We start with the face. Initially we pay attention to the lady at the centre because the face is one of the most important patterns for humans. As adults, we tend to see faces everywhere – in the clouds, on the moon, on the front of VW Beetles. Any pattern with two dots for eyes that has the potential to look like a face is immediately seen as one. It may be a legacy of an adaptive strategy to look out for faces wherever they might be just in case there is a potential enemy hidden in the bushes, or it may simply be that because humans spend so much time looking at faces, we see them everywhere.²⁵

When we look at faces, we concentrate on the eyes, which explains why this region is responsible for generating the most brain activity in observers.²⁶ Eyes serve several communicative purposes because they are directed to pick up visual information and, in doing so, reveal when and where someone’s attention is focused. Gaze behaviour is also a precursor to communication, which is why we try to catch someone’s eye before we strike up a conversation. By watching someone else’s eyes, you can work out what is most interesting to them and when it is appropriate to speak. In face to face conversation, the person listening spends roughly twice the amount of time looking at the speaker, who will periodically glance at the listener, especially when they are making an important point or expecting a response.²⁷ We can gauge how much interest or boredom they are expressing and whether they have been registering the important messages by watching their gaze behaviour.

Not only do we seek out the gaze of others but it can also be difficult to ignore, especially if they are staring at us. This is why it is hard for soldiers standing to attention on a parade ground to maintain a fixed stare ahead of them when the drill sergeant, only inches away, stares at them and commands ‘Don’t eyeball me, soldier!’ This focus requires a lot of discipline. Mischievous tourists notoriously try to make the guards on sentry duty outside Buckingham Palace lose their concentration by getting the soldier to look at them. Trying to avoid eye contact with someone in front of your face is almost impossible. Likewise, if a speaker you are listening to suddenly looks over your shoulder as if to spot something of interest, then you will automatically turn round to see what has captured their attention. This is because most of us instinctively follow another person’s direction of gaze without even knowing it.²⁸

Even infants follow eye gaze. When I was at Harvard, I conducted a study where we showed ten-week-old babies an image of a woman’s face on a large computer monitor.²⁹ She was blinking her eyes open, staring either to the left or right. The babies instinctively looked in the same direction, even though there was often nothing to see.

Gaze monitoring works so well because each human eye is made up of a pupil that opens and constricts to allow varying levels of light into the eye, and a white sclera. This combination of the dark pupil set against the white sclera makes it very easy to work out where someone’s eyes are pointing. Even at a distance, before we can identify who someone is, we can work out where they are looking. In a sea of faces, we are quickest to spot the face whose eyes are directed at us.³⁰

Direct staring, especially if prolonged, triggers the emotional centres of the brain, including the amygdalae, which are associated with the four Fs.³¹ If the other person is someone you like, the experience can be pleasing, but it is distressing if they are a stranger. Newborns prefer faces with a direct gaze³² and, as we saw earlier, if you engage with a three-month-old baby by looking at them, they will smile back at you.³³ However, as children develop, patterns of gaze behaviour change because there are cultural differences in what is regarded as acceptable behaviour.

Cultural norms explain why staring at strangers is common in many Mediterranean countries, but makes foreign tourists often feel uncomfortable at being gawked at when on holiday.³⁴ Likewise, direct eye contact, especially between someone of lower status with someone of higher status such as a student and teacher in Japanese culture, is not considered polite. Japanese adults perceive direct gaze as angrier, unapproachable and more unpleasant.³⁵ Whereas in the West, we tend to think of someone who does not look you in the eye during a conversation as being shifty and deceitful.

When individuals from different cultures with different social norms get together, it can be an uncomfortable exchange as each tries to establish or avoid eye contact. This cultural variation shows that paying attention to another’s gaze is a universal behaviour programmed into our brains at birth, but it is shaped by social norms over the course of our childhood. Our culture defines what are considered appropriate and inappropriate social interactions, influencing our behaviour through emotional regulation of what feels right when we communicate.

Mind games

By signalling the focus of another’s interest, gaze monitoring enables humans to engage in joint attention. How many times have you been in the company of a bore at a party who is droning on and you want to leave with your partner or friend but cannot tell them directly? A roll of the eyes, raised eyebrows and a nod of the head towards the door are all effective non-verbal cues. Even if the other person is a stranger or does not speak your language, you would be able to understand each other without exchanging a word. Joint attention is the capacity to direct another’s interest towards something notable. It is a reciprocal behaviour; you pay attention to what I am focused on and, in return, I pay attention to you. When two individuals are engaged in joint attention, they are monitoring each other in a cooperative act to attend to things of interest in the world.

Other animals, such as meerkats, can direct attention by turning their heads to signal a potential threat. Gorillas interpret direct gaze as a threat, which is why there is a sign at my local Bristol zoo where Jock the 34 stone 6 foot silverback male lives telling visitors not to stare at him. Jock pays attention to gaze as a source of threat, but we are the only species that has the capacity to read the meaning of the eyes over and beyond sex and violence (domesticated dogs being the notable exception that we described in the opening to the book). We use other people’s gaze to interpret the nature of relationships. People who know each other exchange glances and those in love stare at each other.³⁶ This explains those awkward moments that we have all had when we exchange a glance or stare with a stranger in the street or, worse, in an elevator where it is difficult to walk away. Do I know you? Or do you want to be friendly or fight? At a party we can look around and work out who likes each other just by monitoring patterns of joint attention. This ability to work out ‘who likes who’ based on gaze alone develops as we become more socially adept. Six-year-olds can identify who are friends based on synchronized mutual gaze, but younger children find it difficult.³⁷ Joint attention in younger children and babies is really just from the child’s own perspective. If it does not involve them, then they are not bothered. As children become socially more skilled at interacting with others, they start to read others for information that is useful for becoming part of the group.

Joint attention may have evolved as a means to signal important events out in the world in the same way that meerkats use it, but we have developed gaze monitoring into a uniquely human capacity to share interests that enable us to cooperate and work together. No other animal spends as much time engaged in mutual staring and joint attention as humans.

Gaze monitoring is also one of the basic building blocks for social cooperation. We are much more likely to conform to rules and norms if we believe that we are being watched by others. A poster with a pair of eyes reminiscent of George Orwell’s ‘Big Brother’ makes people tidy up after themselves, follow garbage separation rules, voluntarily pay for beverages and give half as much again to charity boxes left in supermarkets.³⁸ Even though individuals may be totally alone, just the thought that they might be watched is enough to get most people to act on their best behaviour. Other people’s gaze makes us become more self-conscious, prosocial and likely to conform.

It is notable that humans are the only primate out of the 200-plus species who have a sclera enlarged enough to make gaze monitoring so easy for us. In humans, the sclera is three times larger than that of any other non-human primate. If you think about it, evolution of the human sclera could not have been for the benefit of the individual alone. There would have been no selective advantage for me with my big white sclera unless there was someone else around to read my eyes. Rather, it had to be of mutual benefit to those who can read my eyes as well as myself.³⁹ It is only of use within a group that learns to watch each other for information.

When infants are learning words from an adult for things they have never encountered before, they listen out for the new name but also monitor where the adult is looking. In one study they were shown a new object and when they were looking at it the experimenter said ‘Look at the toopa’ but at the same time was herself looking into a bucket.⁴⁰ None of the children associated the word ‘toopa’ with the object they were holding. Children understand new words refer to new things but only those that are introduced in the context of shared joint attention.

By their first birthday, babies are constantly monitoring the faces of others, looking for information, and have even mastered the skill of pointing that can alert another to something of interest. Initially, babies point because they want something out of reach. Many primates raised in captivity do this as well, though it is more of an open-handed gesture to receive food. Apes also lack the hand anatomy that allows them to extend the index finger in the same way that humans do. However, only human infants will point to things out of sheer interest.⁴¹ Sometimes this is done to solicit a response from an adult, but more often than not the youngster is simply pointing out something interesting to be shared. No other animal does this.⁴²

Copycats

In addition to joint signalling, we also copy each other. Initially, parents and babies enjoy copying each other’s expressions and noises in reciprocal exchanges. Adults instinctively speak to young babies in that high-pitched, musical, gibberish language in an attempt to elicit smiles and laughter.⁴³ (You may have noticed that couples and pet owners can also do this.) Adults attempt to match the behaviour of the infants because babies respond to it. Sometimes, babies take the initiative and begin to spontaneously copy others around them.

These imitative behaviours are not just limited to language. Facial expressions, hand gestures, laughter and complicated actions can all be observed. Imitation signals to others that we are like them too, and we are the best imitating species on the planet. Andrew Meltzoff from the University of Washington thinks that babies really do this to establish a ‘just like me’ relationship with the adult.⁴⁴ They are using imitation to identify others as friend or foe. The mechanism works both ways. When adults mimic the facial expressions of infants back to them, these signals are telling the baby that this person is one of them.⁴⁵

Before the child has reached their second birthday, they will copy all manner of behaviours. However, this is not slavish mimicry triggered automatically but rather an attempt by the infant to get into the mind of the adult. After watching an adult ‘fail’ to pull the end off a toy dumbbell, eighteen-month-old infants will read the true intention of the adult and complete the task they had never seen before.⁴⁶ In one study, shown in Figure 5, fourteen-month-olds watched an adult experimenter bend over and activate a light by pressing the button with her head (A). For some of the infants, the adult’s hands were bound by a blanket (B).

The babies were then given the light switch to play with. Infants who saw the adult whose arms were bound (B) activated the light switch with their hand because they understood that the adult was unable to use their hands. However, if they were the ones who saw that the adult’s hands were free (A), then the infants bent over and activated the button with their head too. They must have reasoned that it was important to use the head and not the hands. Infants were not simply copying the actions but rather repeating the intended goal. They had to get into the mind of the experimenter in order to work out what they wanted to achieve.⁴⁷

Older children will copy adults’ actions even when the children know the actions are pointless.⁴⁸ In one study, preschoolers watched an adult open a clear plastic box to retrieve a toy. Some of the actions were necessary, such as opening a door on the front of the box, whereas other actions were irrelevant, such as lifting a rod that lay on the top. This behaviour is unique to humans. When presented with these sorts of sequences, children copied both the relevant and irrelevant actions whereas chimpanzees copied only those actions that were necessary to solve a task. The apes behaved in a way that was directed towards the goal of retrieving the reward, whereas for children, the goal was to faithfully copy the adult. Why would children over-imitate a pointless action? For the simple reason that children are more interested in fitting in socially with the adult than learning how to solve the task in the best possible way.⁴⁹