Cambridge Syllabus Notes

🧠 Biological Approaches in AS Level Psychology

What is the Biological Approach?

The biological approach looks at how our bodies, especially the brain and nervous system, shape the way we think, feel and behave. Think of the brain as a bustling city: neurons are the roads, neurotransmitters are the traffic lights, and genes are the city plans that determine how the city is built.

Key Concepts

Neurons & Synapses – The basic units of the nervous system. They communicate via chemical signals called neurotransmitters.
Brain Regions – Different parts of the brain have specialised jobs (e.g., the amygdala for fear, the hippocampus for memory).
Neurotransmitters – Molecules like dopamine, serotonin and norepinephrine that influence mood and motivation.
Genetics & Heritability – Genes can influence traits such as intelligence, personality and risk of mental illness.
Evolutionary Psychology – Explains behaviour as adaptations that helped our ancestors survive.

Important Experiments & Studies

St. M. J. Watson & the Little Albert Study – Demonstrated that fear can be conditioned in humans, showing the brain’s role in learning.
Neuroimaging (fMRI & PET) – Allows us to see which brain areas light up during tasks. For example, the prefrontal cortex lights up during decision making.
Twin Studies – Compare identical and fraternal twins to estimate how much genetics contribute to traits. Example: Heritability of IQ is about 0.7, meaning 70% of variation is genetic.
Lesion Studies – Observing patients with brain damage helps identify functions of specific regions. For instance, damage to the Broca’s area impairs speech production.

Brain–Behaviour Table

Brain Region	Function
Amygdala	Processes emotions, especially fear.
Hippocampus	Critical for forming new memories.
Prefrontal Cortex	Decision making, planning, social behaviour.
Basal Ganglia	Motor control, habit formation.

Exam Tips

Remember:

Use the phrase "biological approach" when asked to explain how biology influences behaviour.
When discussing neurotransmitters, link them to specific behaviours (e.g., dopamine → reward, serotonin → mood).
Use examples like the Little Albert study or fMRI to illustrate key points.
Show understanding of heritability by citing twin studies and explaining the 0.7 figure for IQ.
Include a brief evolutionary perspective when asked how biology explains behaviour.

Quick Maths Check

Heritability (h²) is calculated as: $$h^2 = \frac{V_A}{V_P}$$ where $V_A$ is additive genetic variance and $V_P$ is total phenotypic variance.

For example, if $V_A = 35$ and $V_P = 50$, then: $$h^2 = \frac{35}{50} = 0.7$$ This means 70% of the variation in that trait is due to genetics.

Biological