How the Child's Mind Develops

David Cohen

• Editore: Routledge
• Anno: 2017
• ISBN:
  9781351781800
• Edizione: 3
• Argomento: Psicologia
• Categoria: Storia e teoria della psicologia

• How do we get from helpless baby to knowing teenager?

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• What impact do television, computers and iPads, the internet, video games and evolving technology have on the way children's minds develop?

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• Is cognition a question of learning and environment or of heredity?

How we learn to think, perceive, remember, talk, reason and learn is a central topic in psychology - and one that sees constant new research. In this very readable book, David Cohen discusses the latest studies and covers all the controversies that have dogged the subject for nearly 150 years. He examines the work of the 'greats' like Piaget, Freud and Vygotsky and shows how the issues that have intrigued psychologists relate to any child growing up today.

This book is for everyone who lives with, works with or studies children. David Cohen examines the fundamental issues of how children learn to read and write, of how their intellectual abilities are measured and the development of their morality. He examines child crime and looks at how modern media affect the way the child's mind develops.

This fully updated new edition of How the Child's Mind Develops, which incorporates new extracts from a mother's weekly diary, is an integrated and thought-provoking account of the central issues in child development. Parents, professionals and students will find it an invaluable introduction.

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1

THE DEVELOPING BRAIN

Agatha Christie’s detective Hercule Poirot boasted that his superior brain let him solve murders that baffled Scotland Yard, so he was always careful to keep his little grey cells warm. Marginally less eccentric, P.G. Wodehouse’s clever butler Jeeves believed eating fish kept his brain at peak power.

Outside fiction, it’s proved more difficult to pinpoint just what it is about a person’s brain that gives them remarkable gifts. Do brainy people have a larger brain? Or a different balance of chemicals in the brain? Pathologists have examined the brains of Einstein and Mozart. Given the astonishing work they produced, their brains seemed to be surprisingly like those of ordinary mortals.

Ironically, the more we know about the brain, the more we realise how little we know about it and about how our ability to think develops. The brain remains mysterious – and the way the child’s mind develops is obviously rooted in how the brain develops. Tooby and Cosmides (1998) and Pinker (2009) were perhaps the first to argue that brain structures have possibly changed more in the last million years than conventional accounts allow. Cosmides and Tooby (2015) claim that:

if – as evolutionary psychologists have been demonstrating – the blank slate view of the mind is wrong, then the social-science project of the past century is not only wrong but radically misconceived. The blank slate assumption removes the central causal organizers of social phenomena – evolved psychological programs – from the analysis of social events, rendering the social sciences powerless to understand the animating logic of the social world.

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Evolved psychological programmes are domain-specific adaptations that allow humans to cope in specific circumstances.

This chapter provides:

● a simple guide to the way the brain develops from birth to adulthood;

● descriptions of methods used to study the brain;

● a guide to the many unsolved puzzles about the way children’s brains develop;

● a guide to the methods used in studying children;

● an introduction to the nature versus nurture debate. Is cognitive development the result of heredity and genetics or the result of environment? Or the result of both?

Non-verbal subjects

When the brain is developing most dramatically – in the uterus and then in the first year of life – babies can’t speak.

Let’s say you want to find out if adults can spot the difference between triangles and circles projected for nanoseconds. You might tell your subjects to press the red button when they see a triangle and the green button when they see a circle. You can’t begin to do this if your participants can’t understand the words ‘red’, ‘green’, ‘circle’ or ‘triangle’. That’s precisely the situation facing psychologists when they study babies. To overcome the problem, psychologists have devised several non-verbal methods. These include:

● following the eye movements of babies – studies if a baby is paying attention or concentrating on the people or things it’s looking at;

● providing babies with ‘unexpected’ events – and seeing how they react;

● using trick environments like the visual cliff devised by the American psychologists Gibson and Walk (1960). They wanted to know if babies had any depth vision. They built a glass floor, and babies were set to crawl on it. For the first few feet, the glass was right on top of a real floor, so if babies could understand what they were seeing, they must have realised they were crawling on something solid. After some distance, the floor beneath the glass fell away. The babies came to what looked like the edge of a cliff. Did they stop or continue to crawl? Gibson and Walk reasoned that if they stopped, babies had depth perception and some awareness of danger.

Other methods compare how much babies kick to different stimuli. All these methods are indirect and depend on interpreting the baby’s behaviour.

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FIGURE 1.1 Psychologists have to be inventive when thinking of ways to study infants: in this cleverly designed visual cliff experiment, babies between 6½ months and 12 months of age were reluctant to crawl over the ‘cliff edge’, suggesting they perceived the drop.

The brain is mysterious, so let’s start with some self-observation.

Look at yourself in a mirror. Try to imagine what’s going on inside your head. Write down or draw what you imagine.

There’s no right or wrong answer to the exercise. What matters is that you realise the complexity of the brain. I sometimes imagine it like this: I think of a web of laser lights – many colours, constant pulses of energy, new patterns that make and break and change. This isn’t an accurate description because no one can really provide that yet, but it’s a way of conjuring up images that address key aspects of the problem – the sheer computing power of the brain, and the connections between its cells.

And now, let’s move from the poetic to the straight scientific.

The anatomy of the brain

The brain is an immensely complicated organ with over 100 billion brain cells or neurons, including glial and ganglia cells. The cortex, the top part of the brain, fits over the rest much like a tea cosy covers a teapot. The cortex looks a little like a cauliflower. The brain has four lobes, or, to continue the image, flaps of the tea cosy. They’re called the temporal, frontal, occipital and parietal lobes. Each is named after the skull bone closest to it. These lobes are full of folds or convolutions, as the cells are packed together tightly, under and over each other.

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FIGURE 1.2 The lobes of the brain.

The ‘older’ parts of the brain control basic functions like breathing and balance. All birds, mammals and reptiles also have a cortex, but as one goes up the evolutionary ladder from reptiles to dogs to apes to human beings, the size of the cortex increases. Allowing for the different body sizes of species, human beings have 3.2 times the cortex volume of the great apes. The most sophisticated chimpanzees – including several chimps trained by psychologists – can’t master the skills that come naturally to an average 2-year-old.

The stages of brain growth

What follows requires some effort to grasp, and the following key terms may seem daunting unless you’ve studied biology, but it’s important to master them to get a sense of the structures of the brain:

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Brain cell or neuron: The brain has many kinds of cell. Key brain cells are called neurons. They are either active or not, switched on or off. Messages pass electro-chemically (i.e. through electrical impulses or chemical messengers) from one cell to another. Brain cells form into pathways. Vision, hearing and speech all have their own pathways. It has been argued that when a particular memory is triggered and triggered again, the same pathway of cells becomes active. New thoughts almost certainly trigger new pathways or connections.

Axon: This is the long tube in a neuron that transmits information received by the dendrites to other neurons.

Dendrites: These are the long tentacles or the branching part of the neurons at the end of the axon that receive messages from other cells.

Synapses or synaptic connections: When an impulse reaches the end of the axon of one neuron (cell A), it can’t leap straight to the dendrites or cell body of another cell (cell B). This is because the two cells are separated by a synapse. The word ‘synapse’ comes from the Greek for ‘to clasp’. These synapses are tiny gaps just 200 nanometres wide between cells. Electrical impulses fire from cell A to cell B through chemical substances called neurotransmitters. In certain diseases like schizophrenia or Parkinson’s, these neurotransmitters don’t function properly, so brain cells transmit messages too quickly, too slowly or too chaotically. When you are conscious, millions of cells will be firing in your brain across synaptic gaps.

Myelination: Cells are covered in a myelin sheath. This sheath allows information to pass more quickly down the cell body. Between birth and 2 years of age, the process of myelination proceeds at a dramatic pace.

Development of the brain

The brain starts to be identifiable when the foetus is 3 weeks old, as a slab of cells in the upper part of the embryo. The brain and spinal cord roll into a hollow cylinder. In a few days, brain cells start to form and multiply around the central hollow; then the brain cells move to the wall of the cylinder. This cylinder ‘becomes’ the brain during the 40 weeks in the uterus.

In the womb, the brain develops far more than other parts of the body. As a result, when babies are born, their heads are very large in relation to the rest of their bodies. Two-thirds of the brain is present at birth. In its structure and anatomy, the newborn baby’s brain is remarkably like that of an adult.

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FIGURE 1.3 A brain cell or neuron: electrochemical ‘messages’ are received by the dendrites and transmitted along the axon, from where they are passed on to surrounding neurons.

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Some psychologists suggest the brain is working in a quite sophisticated way even while the baby is still in the womb. Research in Ulster by Peter Hepper (1991) shows that babies whose mothers listen to the Neighbours signature tune while they’re in the womb can recognise that melody very soon after they are born. His work is examined in detail in Chapter 7.

At birth, the baby will have all its 100 billion neural cells in the brain. More brain cells do not sprout after the baby is born and becomes able to see, move and speak. Missing at birth, however, are most of the connections between the cells.

As the baby feels, moves and perceives, these connections are created. From the outset, heredity and environment interact. The baby’s individual experiences create particular pathways and connections between particular cells. A baby brought up in a dark room doesn’t form the pathways needed for normal vision, for example.

‘Making connections’

Films taken of brain cells connecting show the process as quite poetic. Little tentacles spread out from a cell and link up with tentacles from other cells, forming an infinite web.

Figure 1.3 shows some of the connections of one brain cell.

After birth, the dendrites develop spectacularly, reaching out to make contact between brain cells. New synapses form. A good phrase to remember is ‘synaptic exuberance’, which researchers use to refer to the amazing multiplication of synapses after birth.

Again we are dealing with mind-boggling figures. Each neuron is estimated to have an average of 10,000 synapses or connections. Two brain cells will therefore have 1 million connections with other brain cells.

With already 100 billion cells in the brain, that means there are 200,000 times more synapses in one person’s brain than there are human beings on earth. It’s hardly surprising we’re individual.

Size matters

We have seen that human brains are larger than those of other animals. Until recently, psychologists played down the importance of the different sizes of human brains. Recent findings, however, suggest a strong link between intelligence and brain size and weight.

In IQ and Human Intelligence, Mackintosh (1999) pointed out that since 1990, studies of head circumference and IQ all found a positive correlation between brain size and IQ – the larger the brain, the higher the IQ score. The average correlation was +0.38, which is not negligible. The samples in these studies haven’t been small, either; over 2,000 people had their heads measured.

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FIGURE 1.4 The grasp reflex.

Case history: how much of a brain do you need?

In 1848, an explosion blasted a crowbar weighing 13 pounds into the skull of Phineas Gage and pierced his left frontal lobe. It should have killed him, but it didn’t. Soon, he could perform all the tasks he had managed before. His personality changed, however. He became emotional, difficult and, yes, spiky and less engaging. He became very ‘profane’, apparently.

A century later, Lorber also showed how bizarre the brain can be. He studied several Sheffield graduates who had mathematics degrees. In an interview, he told me he found that some of the graduates had large chunks of their cortex missing. Where there should be neurons, often there was only water as cortex, but they behaved normally and did maths rather well. Lorber’s research wasn’t published in a peer-reviewed journal and has been controversial. In 1980, the respected science journalist Roger Lewin wrote a favourable piece about Lorber in Science and called it ‘Is your brain really necessary?’ (Lewin 1980).

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As to the question ‘Is your brain really necessary?’, Lorber admits that it’s only half-serious. ‘You have to be dramatic in order to make people listen’, he told Lewin. Adrian Bower, ...