Key Studies of Neural Networks and Neural Pruning

students, imagine your brain as a giant city with billions of streets, intersections, and delivery routes 🧠🚦 Some routes become busy and important because you use them often, while others fade away when they are not needed. This lesson explores how scientists study that process through neural networks and neural pruning, two ideas that help explain how experience shapes the brain and behaviour in the biological approach to psychology.

By the end of this lesson, you should be able to:

• explain what neural networks and neural pruning are,
• describe key findings from major studies,
• use these studies to support biological explanations of behaviour,
• and apply IB Psychology SL thinking to real situations.

This topic matters because the brain is not fixed like a statue. It changes with development, learning, and experience. Understanding how brain connections are formed and removed helps psychologists explain memory, learning, skill development, and even the effects of early life experience.

Neural Networks: The Brain as a Connected System

A neural network is a set of interconnected neurons that work together to process information. Neurons communicate through electrical signals and chemical messengers, and when groups of neurons repeatedly activate together, the connections between them become stronger. This is often described by the idea “cells that fire together wire together.”

In simple terms, when students practices a skill, the brain builds stronger pathways for that skill. For example, if someone practices playing basketball, the neural network involved in hand-eye coordination, timing, and movement becomes more efficient. This does not mean the brain is “growing” in one obvious way; rather, the pattern of connections becomes better organized and more effective.

Neural networks are important in psychology because they show that behaviour is supported by biological structures that can change. This connects directly to the biological approach, which explains behaviour using the brain, nervous system, hormones, and genetics.

A major idea here is plasticity, which means the brain can change in response to experience. Plasticity is especially strong in childhood, but it continues across life. The key point is that experience can strengthen some neural pathways and weaken others.

Example of a Neural Network in Real Life

Think about learning to type on a phone keyboard 📱 At first, it takes effort to find each letter. With practice, the relevant neural network becomes more efficient, and typing becomes faster and more automatic. The brain is not learning new information only in the abstract; it is changing physically through patterns of activation.

This is why psychologists care about neural networks: they provide a biological explanation for learning and skill development.

Neural Pruning: Why the Brain Removes Connections

Neural pruning is the process by which the brain removes weaker or unused synaptic connections. During early development, the brain creates many more connections than it will keep. Over time, connections that are used often are strengthened, while connections that are rarely used may be eliminated.

This process is useful because it makes the brain more efficient. A child’s brain initially builds a very large number of possible pathways. Later, the brain “selects” the most useful ones and trims away the rest. This is a bit like editing a rough draft: the brain keeps what works best and removes what does not.

Pruning usually happens most strongly during childhood and adolescence. This period is important because the brain is highly sensitive to experience. If a skill, language, or habit is used a lot, the related pathways are more likely to stay. If not, they may be reduced.

Why Pruning Matters

Neural pruning helps explain why early experience is so powerful. For example, a child raised in a language-rich environment will strengthen networks related to language. A child who does not get enough stimulation in certain areas may lose potential connections that could have supported learning.

This does not mean pruning is “bad.” In fact, it is a normal and necessary part of healthy brain development. Without pruning, the brain would keep too many extra connections and may become less efficient.

Key Study 1: Maguire et al. and the Hippocampus in Taxi Drivers

One famous study related to neural networks and brain structure is Maguire et al. (2000). Researchers studied London taxi drivers and compared them with non-taxi drivers using brain scans. Taxi drivers must learn and remember the city’s complex street layout, so their brains offer a useful example of experience shaping neural networks.

The study found that taxi drivers had a larger posterior hippocampus, a region linked to spatial memory and navigation, compared with the control group. This suggests that the brain region involved in route learning was affected by years of intensive use.

The study is important because it supports the idea that the brain changes in response to experience. In other words, repeated use of certain neural networks can strengthen the structures involved.

However, it is important to understand the limits of the study. It was correlational, so it showed an association between taxi driving and hippocampal differences, but it did not prove that driving alone caused the change. There may also have been pre-existing differences.

Still, this study is often used in IB Psychology because it provides strong evidence for neuroplasticity, the brain’s ability to change across time.

Key Study 2: Huttenlocher and Neural Pruning in Development

A second important line of evidence comes from research by Huttenlocher on brain development in children. Huttenlocher studied how synapses change during childhood and found that early brain development involves a large increase in synaptic connections, followed by a decrease through pruning.

The basic finding is that the brain produces an excess of connections early in life, then removes many of them as development continues. This supports the idea that development is shaped by both biology and experience. The brain does not just “grow bigger”; it becomes more specialized.

This research helps psychologists understand why childhood is a sensitive period for learning. If a child is exposed to rich language, social interaction, or structured practice, the useful neural networks are strengthened. If certain experiences are missing, some connections may not be maintained.

In IB Psychology, Huttenlocher’s work is useful because it shows how a biological process can explain behaviour over time. It connects brain development to learning and adaptation.

Key Study 3: Hebb and the Theory Behind Neural Networks

Another foundational contribution is Hebb’s theory of learning, often summarized as “cells that fire together wire together.” Hebb argued that if one neuron repeatedly helps activate another, the connection between them becomes stronger. Even though Hebb’s work was theoretical rather than a single brain-imaging study, it strongly influenced later research on neural networks.

Hebb’s idea helps explain why practice matters. If students studies the same math procedure again and again, the neural pathways involved in that process become more efficient. That is one reason repeated practice improves performance.

This theory is important because it provides a biological explanation for learning without requiring a completely new brain structure each time. Instead, the same network becomes more organized through repeated activity.

Applying These Studies to IB Psychology Reasoning

To answer IB-style questions, students should be able to move beyond simple definitions and explain what the studies show about behaviour.

For example, if asked how biological factors influence learning, you could explain that repeated use strengthens neural networks, while unused connections may be pruned. You could support this with evidence from taxi drivers in Maguire et al. and developmental pruning in Huttenlocher’s research.

If asked about real-world application, you could discuss education or skill learning. A student practicing violin may build stronger motor and auditory networks, while pruning may help the brain focus on the most useful pathways. This shows how biology and experience work together.

A strong IB response often includes:

• a clear definition,
• relevant study evidence,
• explanation of the result,
• and a link back to behaviour.

For example, instead of only saying “the brain changes,” students should say: “Repeated experience strengthens neural networks, which can lead to structural changes in the brain, as shown in Maguire et al.’s study of taxi drivers.”

Why Neural Networks and Pruning Fit the Biological Approach

This topic fits the biological approach because it shows that behaviour can be explained by brain structure and function. The biological approach does not treat the mind as separate from the body. Instead, it studies how physical processes in the nervous system support thoughts, learning, and actions.

Neural networks explain how information is processed in the brain. Neural pruning explains how brain development becomes more efficient over time. Together, these ideas show that behaviour is linked to both inherited biological potential and environmental experience.

This also connects to broader IB themes such as nature versus nurture. Neural pruning is biological, but which connections survive depends partly on experience. That means the brain is shaped by both genetics and environment.

Conclusion

students, the key message of this lesson is that the brain is dynamic and adaptable. Neural networks show how groups of neurons work together to support behaviour, while neural pruning shows how the brain becomes more efficient by removing unused connections. Studies like Maguire et al. and Huttenlocher provide evidence that experience changes the brain across development and adulthood.

In IB Psychology SL, these studies are valuable because they link biological structures to real behaviour. They help explain why practice, learning, and early experience matter so much. The brain is not a fixed machine; it is a living system that changes with use, making it a central topic in the biological approach.

Study Notes

• Neural networks are connected groups of neurons that process information together.
• Neuroplasticity means the brain can change with experience.
• Neural pruning is the removal of weak or unused synaptic connections.
• Pruning is strongest in childhood and adolescence.
• Hebb proposed that repeated activation strengthens connections between neurons.
• Maguire et al. (2000) found that London taxi drivers had a larger posterior hippocampus, supporting the idea that experience can shape the brain.
• Huttenlocher found that synaptic connections increase early in life and then decrease through pruning.
• These studies support the biological approach by showing that behaviour is linked to brain structure and development.
• Key IB skill: explain the study, describe the result, and connect it to behaviour.
• Real-life examples include learning a language, practicing a sport, or developing navigation skills 🧠✨