Edexcel GCSE Psychology: Neuropsychology
Topic 4: The Brain and Neuropsychology — How does your brain affect you?
Paper 1 | Compulsory | 16 marks
This topic covers the structure and function of the brain, how the two hemispheres divide their responsibilities, how neurons communicate with each other, and what happens when the brain is damaged. It is also a possible topic for the 9-mark essay question on Paper 1.
Structure and function of the brain
The brain is divided into two halves called hemispheres. The outer layer, known as the cortex, is folded to increase its surface area and is responsible for higher-order functions. Different regions of the brain are associated with different functions.
The frontal lobe is associated with reasoning, planning, speech, movement, emotions and problem solving. It contains the pre-frontal cortex, which plays a key role in impulse control and decision making.
The temporal lobe is associated with the perception and recognition of auditory stimuli, memory and speech. The fusiform face area, which is involved in face recognition, is located here near the boundary with the occipital lobe.
The parietal lobe is associated with movement, orientation, recognition and the perception of stimuli. Damage here can contribute to visual agnosia.
The occipital lobe is associated with visual processing. It receives and processes information from the eyes.
The cerebellum is located at the back of the brain and is responsible for coordinating movement, balance and motor skills. It receives input from the sensory systems and the spinal cord.
Lateralisation of function
Lateralisation refers to the idea that the two hemispheres of the brain specialise in different functions. The brain shows asymmetrical function, meaning the two hemispheres are not mirror images of each other. Each hemisphere also controls the opposite side of the body.
The left hemisphere is specialised for language, including speech production and understanding. Broca's area, a small region in the left hemisphere, specifically controls speech.
The right hemisphere is specialised for spatial tasks, including recognising faces and interpreting emotions in others.
The two hemispheres communicate primarily through the corpus callosum, a large bundle of nerve fibres connecting the two sides of the brain.
Lateralisation and sex differences
Research suggests that females tend to show less brain lateralisation than males, particularly for language tasks, with more bilateral activity across both hemispheres. Males appear to show greater lateralisation for both language and spatial tasks. This has been used to suggest that females may recover language more easily after a one-sided brain injury.
Evaluation
One strength is that Sperry's (1968) split-brain research provided strong evidence that the two hemispheres have distinct specialisations, supporting the idea that lateralisation is a real and significant aspect of brain organisation.
One weakness is that differences between males and females in lateralisation are small and inconsistent across studies. Many researchers argue these differences are too modest to explain meaningful behavioural differences between the sexes, and that social and cultural factors also matter.
Neurons, synapses and the central nervous system
The central nervous system (CNS) is made up of the brain and the spinal cord. It is connected to the rest of the body through the peripheral nervous system, which carries messages to and from the muscles, skin and organs.
Neurons are specialised cells that carry electrical signals. A neuron consists of a cell body, dendrites (which receive incoming signals) and an axon (which carries the signal away from the cell body) ending in terminal buttons.
Neurons communicate across tiny gaps called synapses. When an electrical signal reaches the terminal button, it triggers the release of chemical messengers called neurotransmitters from vesicles. These cross the synapse and bind to receptors on the next neuron, either triggering or inhibiting a new signal.
Key neurotransmitters include dopamine (involved in attention, learning and the reward system), serotonin (regulates mood — low serotonin is linked to depression) and GABA (has an inhibitory, calming effect on the nervous system).
The impact of neurological damage
Neurological damage refers to damage to the brain or nervous system, which can disrupt the normal processing of information and alter a person's thinking, behaviour and personality.
Visual agnosia
Visual agnosia is a disorder in which a person can see perfectly well but cannot make sense of what they are seeing. The eyes send information to the brain normally, but the brain is unable to interpret and recognise it. For example, a person with visual agnosia might be shown a kettle but be unable to name it, even though they can see and describe its shape and colour. Visual agnosia is typically caused by damage to the parietal or occipital lobes.
Prosopagnosia
Prosopagnosia, also known as face-blindness, is the inability to recognise faces, even those of familiar people. A person with prosopagnosia can see faces clearly but cannot identify who they belong to. In severe cases, people cannot recognise close family members or their own reflection. They typically rely on other cues such as voice, hairstyle or clothing. Prosopagnosia is caused by damage to the fusiform face area in the temporal lobe.
Damage to the pre-frontal cortex
The pre-frontal cortex is responsible for impulse control, decision making and emotional regulation. When damaged, people can become impulsive, aggressive and emotionally unpredictable, and their personality may seem to change significantly. Research by Raine et al. found that convicted murderers showed reduced activity in the pre-frontal cortex compared to a control group, suggesting a link between pre-frontal damage and violent, impulsive behaviour.
Key studies
Damasio et al. (1994) — The Return of Phineas Gage: Clues About the Brain from the Skull of a Famous Patient
Background: in 1848, Phineas Gage survived an accident in which an iron rod was driven through his skull. His personality changed dramatically afterwards — from calm and responsible to irresponsible, rude and anti-social — suggesting the frontal lobe damage had altered his behaviour.
Aim: to use modern methods to identify precisely which areas of Gage's brain had been damaged, and whether areas beyond the frontal lobe had also been affected.
Procedure: the researchers used Gage's preserved skull to create a three-dimensional computer reconstruction and simulated the trajectory of the iron rod to identify which brain regions would have been damaged.
Results: damage was concentrated in the ventromedial region of the pre-frontal cortex in both hemispheres. White matter connecting brain regions was also damaged. Other areas appeared to have been spared.
Conclusion: the ventromedial pre-frontal cortex plays an important role in decision making, social behaviour and emotional regulation. Damage to this area can cause significant and lasting personality changes.
Strengths: modern brain imaging technology allowed the researchers to identify damage with far greater precision than was possible in Gage's lifetime, demonstrating how psychology advances over time with new methods.
Weaknesses: the study is a single case, so findings cannot be generalised. Some details of Gage's behaviour before and after the accident are based on second-hand accounts, which may not be fully reliable.
Sperry (1968) — Hemisphere Deconnection and Unity in Conscious Awareness
Background: in some patients with severe epilepsy, the corpus callosum was surgically cut to prevent seizures spreading between hemispheres. Sperry used these split-brain patients to investigate what each hemisphere could do independently.
Aim: to investigate the cognitive functions associated with each hemisphere and the effects of severing the corpus callosum.
Procedure: 11 split-brain patients completed a series of tasks in which information was presented to either the left or right visual field for 1/10 of a second — too fast for eye movements to redirect it. In key tasks, images or words were flashed to one side of the screen and patients had to select a matching object by touch from behind a screen. Other tasks tested language, recognition and spatial abilities in each hemisphere separately.
Results: when information was shown to the right visual field (left hemisphere), patients could name it verbally. When shown to the left visual field (right hemisphere), they could not name it but could select the matching object by touch. Each hemisphere appeared to have independent memories and perceptions. The left hemisphere was superior for language; the right for spatial and tactile tasks.
Conclusion: the two hemispheres have distinct, specialised functions. When they cannot communicate, each operates independently, revealing clear lateralisation.
Strengths: the highly controlled procedure ensured information was presented to only one hemisphere at a time, allowing clear conclusions about each side's functions. The study provided the most direct and influential evidence for lateralisation.
Weaknesses: the sample of only 11 participants, all with severe epilepsy who had undergone major surgery, limits generalisability. The artificial tasks may not reflect how the hemispheres function in everyday life.
Issues and debates: how psychology has changed over time
This topic illustrates how understanding of the brain has developed as research methods and technology have advanced.
In the Roman era, knowledge came largely from dissection. The development of the microscope from the late 1500s allowed scientists to see neurons for the first time. Brain scanning technology transformed neuropsychology in the second half of the 20th century: CAT scans became available in 1972, PET scans in 1975 and MRI scans in 1977, allowing researchers to observe the living brain without surgery.
The case of Phineas Gage in the 19th century suggested for the first time that specific brain regions were linked to personality, but it was only with Damasio et al.'s (1994) computer reconstruction that the precise damage could be identified. This shows how the same historical case can yield new insights as technology improves.
Sperry's (1968) research on lateralisation was later built upon by researchers investigating sex differences in brain organisation, showing how psychological knowledge accumulates and develops over time rather than being fixed and final.
Key terms
Frontal lobe: the brain region associated with reasoning, planning, speech, movement, emotions and problem solving.
Temporal lobe: the region associated with auditory perception, memory and speech.
Parietal lobe: the region associated with movement, orientation and the perception of stimuli.
Occipital lobe: the region associated with visual processing.
Cerebellum: the structure at the back of the brain that controls movement, balance and motor coordination.
Lateralisation: the idea that different functions are specialised in different hemispheres of the brain.
Asymmetrical function: the two hemispheres perform different functions rather than being mirror images.
Corpus callosum: the bundle of nerve fibres connecting the two hemispheres.
Neuron: a specialised cell that transmits electrical signals through the nervous system.
Synapse: the gap between two neurons across which neurotransmitters are released.
Neurotransmitter: a chemical messenger that crosses the synapse and influences the activity of the next neuron.
Central nervous system (CNS): the brain and spinal cord, which together form the control centre of the body.
Visual agnosia: the inability to recognise objects that can be seen, caused by damage to the brain's visual processing areas.
Prosopagnosia: the inability to recognise faces (face-blindness), caused by damage to the fusiform face area.
Pre-frontal cortex: the front part of the frontal lobe, responsible for impulse control, decision making and emotional regulation.
Split-brain: a condition in which the corpus callosum has been severed, meaning the two hemispheres cannot communicate directly.
Looking for revision resources for this topic? The Neuropsychology Knowledge Organiser covers all of the above in a format designed for efficient revision.