Neural Networks and Neural Pruning

Welcome, students 👋 In this lesson, you will learn how the brain changes as we grow, how groups of neurons work together, and why some brain connections become stronger while others are removed. These ideas help explain how behaviour develops in infancy, childhood, and adolescence. By the end of the lesson, you should be able to:

• explain the main ideas and terms behind $\text{neural networks}$ and $\text{neural pruning}$,
• use these ideas to explain behaviour in real life,
• connect this lesson to the broader $\text{biological approach}$ in psychology,
• and describe evidence from research that supports these concepts.

Think of the brain like a city full of roads 🚗. Some roads are used all the time and become smoother and faster. Other roads are used rarely and may close down. The brain works in a similar way through connections between neurons.

What Are Neural Networks?

A $\text{neural network}$ is a group of neurons that work together to process information. A neuron is a nerve cell that sends electrical and chemical messages. When many neurons are connected, they form pathways that help the brain complete tasks such as seeing, hearing, moving, remembering, and making decisions.

In simple terms, neural networks are the brain’s communication system. When you read a sentence, many networks are active at once. Some networks help you recognize letters, others help you understand meaning, and others connect the words to memory. This is why thinking and behaviour are not controlled by just one brain area. Instead, they usually depend on many connected areas working together.

A key idea in the biological approach is that behaviour has a physical basis in the brain and nervous system. Neural networks fit this idea perfectly because they show how brain structure is linked to behaviour. For example, when a student learns to type faster, the brain networks involved in finger movement and visual processing become more efficient.

Neural networks are also important because they can adapt. This adaptability is called $\text{neuroplasticity}$, which means the brain can change with experience. If students practices a skill regularly, the relevant neural connections may become stronger. This is one reason practice improves performance in sports, music, and studying.

How Neural Networks Develop and Strengthen

Neural networks are not fixed from birth. They develop through a mix of genetic influences and experience. Some basic brain connections are present early in life, but many are refined through learning and interaction with the environment.

When a neuron sends a message to another neuron, the connection between them can become stronger if it is used often. This is often explained with the phrase “cells that fire together, wire together.” In psychology, this means that repeated activation of a pathway makes it easier for that pathway to activate again. Over time, this can improve memory, skill learning, and automatic behaviour.

For example, imagine students is learning to play basketball. At first, dribbling, aiming, and moving at the same time may feel difficult. But after practice, the brain builds stronger networks for coordination and timing. The behaviour becomes smoother because the relevant neural pathways are used again and again.

This idea also helps explain why early life experiences matter. Young brains are especially sensitive to input from the environment. If a child hears language often, the neural networks for speech and language develop strongly. If a child is not exposed to enough stimulation, some pathways may not develop as efficiently. This does not mean the brain cannot change later, but early experiences can have a major impact.

Neural networks are therefore important in IB Psychology because they show how behaviour is influenced by both biology and experience. The brain is not just “hard-wired.” It is constantly being shaped by what a person does, learns, and feels.

What Is Neural Pruning?

$\text{Neural pruning}$ is the process by which the brain removes weaker or unused neural connections. This happens as the brain matures, especially during childhood and adolescence. The process helps the brain become more efficient.

At first, the brain produces many more neural connections than it will keep. This creates a kind of “extra” network. Then, through experience, the brain strengthens the pathways that are used often and prunes away those that are used less often. This is similar to trimming a tree 🌳. Removing extra branches allows the tree to grow more efficiently.

Neural pruning is important because it reduces unnecessary connections and makes brain processing faster and more organized. A brain with too many weak connections would use more energy and may be less efficient. Pruning helps improve attention, learning, and decision-making by keeping the most useful pathways.

A useful way to think about pruning is this: if students studies math every week, the neural pathways used for math skills are likely to be kept and strengthened. If another pathway is rarely used, it may weaken and eventually be pruned. This is not a punishment or a mistake. It is a normal part of brain development.

Neural pruning is especially active during adolescence. This stage is important because teenagers often show major changes in thinking, emotion, and self-control. The brain areas involved in planning and impulse control are still developing, and pruning helps make these systems more efficient. This can help explain why adolescents may sometimes take more risks, even though their brains are still becoming more organized.

Why Neural Pruning Matters for Behaviour

Neural pruning helps explain how behaviour changes over time. It shows that the brain develops by keeping useful connections and removing less useful ones. This means experience can shape the brain’s structure and therefore shape behaviour.

One real-world example is language learning. A young child exposed to two languages may build strong neural networks for both. Later, continued use of both languages helps maintain these pathways. If one language is rarely used, some of its related pathways may weaken. This shows how behaviour and environment influence brain development.

Another example is skill development in sports or music 🎵. A person who practices piano regularly strengthens networks for hand coordination, auditory processing, and memory. Over time, pruning helps make these networks more efficient, which can lead to quicker responses and better performance.

Neural pruning also supports the idea that the brain becomes more specialized as it develops. Instead of using many possible pathways for every task, the brain keeps the most efficient ones. This specialization is one reason adults can process certain tasks faster than young children.

In IB Psychology, students should connect this to the biological approach by showing that behaviour is not just a result of thinking or environment alone. It is also influenced by the structure and function of the brain. Neural networks and pruning give clear evidence that biological processes and experience work together.

Evidence and Research in Biological Psychology

IB Psychology often asks students to use empirical evidence, which means evidence gathered through observation or experiment. Research on brain development supports the ideas of neural networks and pruning.

Studies using brain imaging have shown that the brain changes with age and experience. For example, scans of developing brains show that grey matter volume changes during childhood and adolescence, which is consistent with the idea of pruning. Researchers have also found that practice-related learning can alter brain pathways, showing that neural networks are shaped by experience.

One well-known example comes from studies of children and adolescents using MRI scans. These studies show that areas involved in higher thinking, such as planning and self-control, develop gradually and do not mature at the same time as emotional areas. This helps explain why adolescents may show strong emotions but still have developing impulse control. The pattern is consistent with ongoing pruning and strengthening of neural pathways.

Animal research has also contributed to this topic. Scientists have observed that young animals exposed to different environments can show differences in brain development. Richer environments tend to support stronger brain growth and more complex connections, while less stimulating environments can lead to reduced development in some areas. This supports the idea that experience affects neural networks.

When writing an IB Psychology response, students should not simply describe the brain. It is important to link the evidence to behaviour. For example, if a study shows that practice changes brain pathways, the psychological conclusion is that learning can physically shape behaviour through neural networks.

Conclusion

Neural networks and neural pruning are central ideas in the biological approach to understanding behaviour. Neural networks show how groups of neurons work together to support learning, memory, and action. Neural pruning shows how the brain becomes more efficient by removing weak or unused connections. Together, these processes explain why the brain changes across the lifespan and why experience matters.

For IB Psychology SL, the key is to connect brain development to behaviour using accurate terminology and real examples. If you can explain how networks strengthen with use and how pruning removes less useful connections, you will have a strong understanding of this lesson. These ideas show that behaviour is rooted in biology, but shaped by experience too 🧠

Study Notes

• $\text{Neural networks}$ are groups of connected neurons that work together to process information.
• $\text{Neural pruning}$ is the removal of weaker or unused neural connections as the brain develops.
• The brain is shaped by both genetics and experience.
• Repeated use strengthens neural pathways; unused pathways may weaken and be pruned.
• Pruning helps the brain become more efficient and specialized.
• This process is especially important during childhood and adolescence.
• Neural networks and pruning support the $\text{biological approach}$ because they show that behaviour is linked to brain structure and function.
• Real-life examples include learning language, playing sports, and practicing music.
• Empirical evidence from brain imaging and developmental research supports these ideas.
• In IB Psychology answers, always link brain processes to behaviour and use correct psychological terms.