The Domesticated Brain (26 page)

Our capacity for imitation is supported by brain mechanisms that form part of the so-called
mirroring system
– a network of brain areas that include neurons in the motor cortex that control our movements. These neurons are normally active when we are planning and executing actions. However, back in the 1990s in Parma, Italy, researchers chanced upon a discovery about motor neurons that was to change the way we think about ourselves and what controls our actions. Vittorio Gallese and colleagues had been measuring from a neuron in the premotor cortex of a rhesus
macaque monkey, using a very fine electrode.
¹⁰
The cell burst into activity when the monkey reached for a raisin. That was to be expected as it was a premotor neuron that initiates movements. However, the Italian researchers were astonished when the same cell also fired as the monkey watched the human researcher reach for a raisin. The monkey’s brain was registering the experimenter’s reaching; an activity that was controlled by the human brain.

The reason this is remarkable is that it used to be thought that the areas for perceiving others’ actions were different from the network for producing your own movements. Instead, the Italian researchers had discovered that around one in ten neurons in this region were ‘mirroring’ the behaviour of others. It was as if these mirror neurons in the monkey’s brain were pantomiming the actions of others. As neuroscientist Christian Keysers explained, ‘Finding a premotor neuron that responds to the sight of actions was as surprising as discovering that your television, which you thought just displayed images, had doubled all those years as a video camera that recorded everything you did.’
¹¹

This dual role of copying other people’s behaviour and executing your own set the scientific community alight. Direct mapping between our brain and the brains of others, by observing them, could explain why we cry at weddings, feel others’ pain, emotional contagion and all manner of social behaviours that seem to reveal the human capacity for mimicking. It was as though scientists had found a direct psychic connection between the minds of others. It was even announced that the discovery of mirror neurons was
as significant to understanding the brain as the discovery of the structure of DNA was to biology; while this is an exaggeration, it captures the excitement mirror neurons generated.
¹²

Others were more sceptical because recording directly from neurons in the brain of a human had not been done. However, in 2010, neurosurgeon Itzhak Fried published a study
¹³
of patients he had been treating for epilepsy. To isolate the affected brain region, he implanted electrodes to determine which areas to surgically remove – much in the same way that Wilder Penfield had done all those years earlier with his neurosurgery patients. During this procedure, the patients were fully conscious and able to take part in a study designed to establish the presence of mirror neurons once and for all. They were asked to either smile, frown, pinch their index finger and thumb together or make a whole grip with their hand. When Fried found neurons that were activated during one of these movements, the patients were then shown a video of someone else making the same types of movements. Just as in the macaque monkey, premotor neurons were activated both by making a movement and also by watching someone else perform exactly the same action –
bona fide
mirror neurons in humans. The real burning question is how did they get there?
¹⁴
Are they simply neurons that have acquired their dual activity after years of watching others and mapping their behaviour to one’s own movements? Or are babies already prepackaged with mirror neurons, which might explain reports where newborns have been shown to copy adult facial expressions without any learning?

The ‘in’ crowd

As we read in
Chapter 2
, there are reasons to believe that we may be born with a rudimentary capacity for mimicking others. Infant mimicry is instinctual but the system is not simply a dumb mechanism that slavishly copies every Tom, Dick or Harry a child encounters. Rather, infants become more discerning of others, assessing whether they are friend or foe. Initially, this distinction is drawn between those that share the same interests and preferences as the baby. In a food-preference study,
¹⁵
eleven-month-olds were offered the choice of crackers or cereal from two bowls. Having made their choice, they watched as two puppets came along and approached the food. For each bowl, one puppet said, ‘Hmm, yum, I like this’ and the other said, ‘Ewww, yuck, I don’t like that.’ Each puppet expressed the opposite attitude to each food. The infant was then offered the choice to select to play with one of the puppets. Four out of five infants chose the puppet that had the same food preference as him or herself, irrespective of whether it was crackers or cereal. Before they have reached their first birthday, babies are showing clear signs of preference and prejudice. Just as their brains are tuning into the faces and voices that surround them, so too are they learning to identify who is, and who is not, like them.

To make this distinction, one has to have a sense of self-identity – knowing who we are and how we differ from others. This emerges most conspicuously during the second year of life. Famously, humans and other social animals
recognize themselves in mirrors.
¹⁶
Initially young infants treat their reflected image as a playmate, but around eighteen to twenty months they begin to show reliable mirror identification, indicating a new level of self-awareness.
¹⁷
Somewhere between two and three years of age, children begin to show signs of embarrassment as indicated by blushing. As blood flushes our skin, reddening our face, blushing is an indicator of being uncomfortable in a situation that attracts the undesired attention of others. As Charles Darwin noted,

It is not the simple act of reflecting on our own appearance, but the thinking what others think of us, which excites a blush. In absolute solitude the most sensitive person would be quite indifferent about his appearance.
¹⁸

Why blushing evolved is a bit of a mystery, but one suggestion is that it could work as a visual apology to others, thereby averting social ostracism.
¹⁹
The problem with that is that blushing is not obvious in dark-skinned people and we were all dark once. Did it evolve its signalling properties only after the migration out of Africa? Nobody really knows why humans are the only animal that blushes, but the fact that it only occurs in the company of others means it must be related to signalling our sense of shame and guilt – emotions that depend on what we think others are thinking about us.

Self-awareness in children is also signalled by the appearance of the use of personal pronouns that we talked about in the last chapter when it comes to owning stuff. Towards the end of the second year, children are using ‘I’, ‘me’, ‘mine’, but they are also using gender labels such as ‘girl’, ‘boy’, ‘man’ and ‘woman’ – though females are ahead of males simply
because they are generally more advanced with language.
²⁰
This self-labelling as a boy or girl is one of the first markers of identity. Infants are sensitive to gender much earlier because they all show preferences for the female face at three to four months of age,
²¹
but by the time they are two years old, most have a preference for their own gender.
²²
In fact, sensitivity to gender predates racial prejudice that appears much later. When asked to select potential friends from photographs, three-and four-year-olds show a reliable preference for their own gender but not their own race.
²³

Once they know they are a boy or a girl, they become
gender detectives
, seeking out information about what makes boys different from girls.
²⁴
This is when they begin to conform to the cultural stereotypes present in society. Not only are they gender detectives but they also police the differences as enforcers, criticizing those who display attitudes or behaviours associated with the opposite gender. By three to five years of age, children are already saying negative things about other children who they do not identify with. They are making a distinction between in-groups and out-groups. If you are in my gang, then we are both in-group members.

Initially group identity is gender specific but it can be based on something as trivial as dress code, which is why three-year-olds will prefer other children who wear the same-coloured T-shirt as themselves.
²⁵
Child psychologist Rebecca Bigler at the University of Texas in Austin, who has spent twenty-five years studying interventions aimed at countering children’s bigotry, has concluded that once the child develops a prejudicial social stereotype, it can be almost impossible to get them to abandon it – ‘In the case of
stereotyping and prejudice, it may well be that an ounce of prevention is worth a pound of cure.’
²⁶

Knowing me, knowing you

When we think about ourselves and others, certain areas are activated in our brains. Harvard neuroscientist Jason Mitchell,
²⁷
one of the new vanguard of researchers in the field of social cognitive neuroscience, has pointed out that there is good evidence that there may be four to six regions that form networks that are consistently activated in social situations and not in other types of problem solving. If you are asked to imagine whether or not a historical figure like Christopher Columbus would know what an MP3 player is, this type of question activates these socially sensitive networks. This is because you have to infer the mindset of Columbus and imagine what he would think. However, if you ask whether an MP3 player is smaller than a bread bin, these areas remain silent. This is because the question now becomes a perceptual judgement based on your knowledge about the size relationship between different physical objects.

One of the circuits activated by social encounters is the mirroring system and includes regions where the mirror neurons we mentioned earlier have been found. This circuitry registers the physical properties of others as well as our own body shape and movements. It includes the premotor areas, parts of the frontal cortex and the parietal lobes – all regions involved in actions. The integration of neural systems that represent both our own bodies and the bodies of others can explain why watching the suffering of another person when
they are in pain also triggers our own corresponding brain regions.
²⁸

In addition to a system that registers the physical similarities with another person, another circuitry is activated when we contemplate ourselves, compared to thinking about others. This mentalizing system involves the medial prefrontal cortex (MPFC – the region in the middle of your forehead), the temporal-parietal junction (TPJ – where the two lobes meet, which is a couple of inches above the temples) and the posterior cingulate (PC – located close to the crown of the head) and appears to support thought processes when you are thinking about yourself. These contemplations include the relatively stable aspects of our personality that we have insight into, such as ‘I am really quite an anxious person’, as well as ever-changing feelings such as ‘I am feeling quite confident at the moment’. This circuitry is also active when we mentally time travel to think about the past or imagine our self in the future.

Both stable and transitory self-reflection show up as increased activation of the MPFC.
²⁹
Self-reflection also includes the extended self of objects. In the same way that there is a characteristic P300 brain signal that registers stuff that belongs to you, as discussed in the last chapter, the MPFC is activated in situations where the endowment effect is triggered, which supports the idea that this region is part of the neural representation of at least one aspect of self.
³⁰

The self-reflection system is not just about naval gazing, however. It enables us to imagine our self in different situations that others might face. This sort of ability would enable one to self-project or simulate another person’s
situation possibly as a way of understanding what their thought processes or emotions might be. The Scottish social neuroscientist Neil Macrae has described the MPFC system as a kind of
knowing me, knowing you
mechanism. In other words, when you are making judgements about other people, you are really comparing them to yourself. This is why, when adults are asked to judge others, the more objectively similar they are to the person they are thinking about, the more activation is observed in their own MPFC.

Once we identify with others in our group, we are more likely to mimic and copy them. These are acts of affiliation, signalling our allegiances. We want to be seen to be like others in the group in order to consolidate our position. However, if someone from an out-group copies us, we interpret this mimicry as mockery – an act of provocation. It is not enough that we like those who like us, but we are actively suspicious of others who are not in our tribe.
³¹