Biological approach

The biological approach in psychology investigates how physiological structures, genetic factors, and neurochemical processes influence behaviour and mental processes. This perspective assumes that all psychological phenomena have biological underpinnings that can be scientifically measured and studied.

Key Terms & Definitions:

Neurons are specialized cells that transmit electrical and chemical signals throughout the nervous system. They consist of dendrites (receive signals), cell body (processes information), axon (transmits signals), and terminal buttons (release neurotransmitters).

Neurotransmitters are chemical messengers released at synapses that facilitate communication between neurons. Examples include serotonin (mood regulation), dopamine (reward and motivation), and acetylcholine (memory and learning).

Brain localization refers to the principle that specific brain regions are responsible for particular functions. The hippocampus processes memory consolidation, the amygdala processes emotional responses, and the prefrontal cortex manages executive functions.

Hormones are chemical messengers secreted by endocrine glands that travel through the bloodstream to affect behaviour. Cortisol regulates stress responses, while oxytocin influences social bonding.

Genetics examines how inherited DNA influences behaviour. Genotype refers to genetic makeup, while phenotype describes observable characteristics resulting from gene-environment interaction.

Mnemonic for neuron structure: Debbie's Cat Ate Tuna (Dendrites → Cell body → Axon → Terminal buttons)

Cambridge Focus: Understand that the biological approach emphasizes reductionism—explaining complex behaviours through simpler biological components—and determinism—suggesting biology predetermines behaviour.

The biological approach manifests powerfully in understanding mental health conditions and their treatments. Consider depression: biological psychologists identify that reduced serotonin and norepinephrine levels correlate with depressive symptoms. This understanding led to developing Selective Serotonin Reuptake Inhibitors (SSRIs) like Prozac, which increase serotonin availability at synapses.

Brain Plasticity Analogy: Think of your brain like a forest trail system. Frequently traveled paths (repeated behaviours) become well-worn and easy to navigate, while unused paths become overgrown. When you learn new skills or recover from brain injury, you're essentially creating new trails—this is neuroplasticity. Stroke patients relearning speech exemplify this: undamaged brain regions gradually assume functions of damaged areas.

Real-World Application—PTSD Treatment: The amygdala (emotion center) becomes hyperactive in Post-Traumatic Stress Disorder patients. Understanding this biological basis enabled development of propranolol, a beta-blocker that reduces physiological anxiety responses. Administered shortly after trauma exposure, it may prevent PTSD development by interfering with fear memory consolidation.

Cortisol and Exam Stress: Students experiencing exam anxiety demonstrate elevated cortisol levels. Chronic elevation impairs hippocampal function—ironically making memory recall harder during exams. This biological understanding validates stress-reduction techniques: deep breathing activates the parasympathetic nervous system, counteracting cortisol's effects.

Genetic Example—PKU: Phenylketonuria illustrates gene-environment interaction beautifully. Individuals with PKU genotype cannot metabolize phenylalanine. Without dietary intervention (environmental factor), toxic buildup causes intellectual disability. With proper diet from birth, individuals develop normally—demonstrating that genetic determinism isn't absolute.

Cambridge Connection: Examiners value examples demonstrating interactionism—how biology interacts with environment, not biology alone determining outcomes.

Example 1: Explain how neurotransmission occurs at the synapse. [6 marks]

Examiner's Approach: Define terms, describe process sequentially, use accurate terminology.

Model Answer: Neurotransmission begins when an action potential (electrical impulse) travels down the presynaptic neuron's axon to the terminal buttons. This electrical signal triggers voltage-gated calcium channels to open, allowing Ca²⁺ ions to enter the terminal. The calcium influx causes synaptic vesicles containing neurotransmitters to migrate toward and fuse with the presynaptic membrane through exocytosis.

Neurotransmitters are released into the synaptic cleft (gap between neurons) and diffuse across to the postsynaptic neuron. They bind to receptor sites on the postsynaptic membrane, functioning like a lock-and-key mechanism. This binding causes ion channels to open, triggering either excitatory effects (depolarization, increasing firing likelihood) or inhibitory effects (hyperpolarization, decreasing firing). Finally, neurotransmitters are cleared from the synapse through reuptake (transported back into presynaptic neuron), enzymatic degradation, or diffusion.

Examiner Notes: Answer includes process stages, technical terminology, and mechanism explanations—hitting all assessment criteria.

Example 2: Evaluate the use of animal research in studying the biological basis of behaviour. [8 marks]

Structure: Introduction → Strengths (2 points) → Limitations (2 points) → Conclusion

Model Answer: Animal research has significantly advanced understanding of biological psychology, though ethical concerns warrant consideration.

Strengths: Researchers can conduct controlled experiments impossible with humans. Maguire et al.'s study on London taxi drivers' hippocampal enlargement built upon foundational rat maze studies demonstrating hippocampal involvement in spatial memory. Additionally, animals' shorter lifespans enable multi-generational genetic studies—Rosenzweig's enriched environment research with rats demonstrated neuroplasticity principles applicable to human development.

Limitations: Generalizability poses challenges; human brains possess unique features like advanced prefrontal cortex development and language capabilities. Furthermore, ethical concerns about animal welfare conflict with research benefits—the three Rs principle (Replacement, Reduction, Refinement) attempts balancing scientific progress with moral responsibility.

Conclusion: While animal research provides crucial insights into fundamental biological processes, findings require human validation, and ethical oversight remains essential.

Examiner Notes: Balanced evaluation, specific studies cited, ethical dimension addressed—demonstrates higher-order thinking.