What do Alzheimer's disease and aphantasia reveal about how memory and mental imagery normally work?
the contribution that brain conditions such as Alzheimer's disease and aphantasia can make to the understanding of memory, with reference to the role of brain structures and the absence of mental imagery
A focused answer to the VCE Psychology Unit 3 dot point on memory conditions. Covers Alzheimer's disease as a neurodegenerative condition affecting memory and brain structures, aphantasia as the inability to generate mental imagery, and what each reveals about how normal memory and imagination work.
Reviewed by: AI editorial process; not yet individually human-reviewed
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What this dot point is asking
VCAA wants you to explain how two contrasting conditions deepen our understanding of memory: Alzheimer's disease, a progressive neurodegenerative condition that destroys neural tissue and erodes memory, and aphantasia, the inability to voluntarily generate mental imagery. You should link Alzheimer's to specific brain structures (especially the hippocampus) and explain what aphantasia reveals about the role of imagery in remembering and imagining.
The answer
Studying conditions that disrupt memory tells us which brain structures and processes normal memory depends on. The two named here disrupt memory in very different ways.
Alzheimer's disease
Alzheimer's disease is a neurodegenerative disease, meaning it involves the progressive death of neurons and loss of brain tissue. It is the most common cause of dementia, a broad decline in cognitive functioning severe enough to interfere with daily life.
The biological hallmarks are the build-up of amyloid plaques (abnormal protein deposits between neurons) and neurofibrillary tangles (twisted protein fibres inside neurons). These disrupt communication between neurons and trigger their death, causing the brain to physically shrink (atrophy) as the disease advances.
The damage is not uniform. Early in the disease it concentrates in the hippocampus, the structure responsible for forming new explicit (declarative) memories. This explains the classic early symptom: the person can still recall events from long ago (older long-term memories) but cannot form new memories, repeatedly forgetting recent conversations and events. Anterograde amnesia, the inability to form new memories, is therefore an early and prominent feature, while older, consolidated memories survive until later stages.
What Alzheimer's reveals is the central role of the hippocampus in forming new explicit memories and the distinction between forming new memories and retrieving old ones. The way the disease dismantles memory in a particular order maps onto how memory is normally organised in the brain.
Aphantasia
Aphantasia is the inability to voluntarily generate mental images in the mind's eye. A person with aphantasia, asked to picture a beach, cannot conjure a visual image, though they still know all the facts about a beach. It is not a memory disorder in the sense of forgetting; the information is retained, but it cannot be experienced as imagery.
Crucially, people with aphantasia can still remember facts and events, so their semantic memory and much of their episodic memory remain intact. What is affected is the visual richness of recollection and, importantly, the ability to visualise imagined futures. Because picturing a future scene normally relies on generating mental imagery, aphantasia can blunt that constructive process even while factual knowledge is preserved.
What aphantasia reveals is that mental imagery is a separable component of memory and imagination. The fact that a person can retain information yet be unable to picture it shows that storing knowledge and generating a mental image are distinct processes, drawing on partly different mechanisms.
What the two conditions teach us together
The two conditions illuminate memory from opposite directions.
- Alzheimer's shows that destroying a specific structure (the hippocampus) selectively destroys a specific function (forming new explicit memories), demonstrating the localisation of memory functions in the brain.
- Aphantasia shows that even with memory storage intact, the subjective imagery that usually accompanies remembering and imagining can be absent, separating the content of a memory from its visual experience.
Together they support the picture built across this area of study: memory is not a single faculty but a set of interacting systems, each with its own neural basis.
Exam-style practice questions
Practice questions written in the style of VCAA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
2025 VCAA2 marksWidespread research is being conducted on how gut microbiota might influence Alzheimer's disease through the gut-brain axis. Explain why Alzheimer's disease impacts the retrieval of autobiographical events.Show worked answer →
Two marks: link the brain damage in Alzheimer's disease to the memory system that retrieves autobiographical (episodic) events.
The damage. Alzheimer's disease causes progressive degeneration of brain tissue, with early and severe damage to the hippocampus and surrounding structures, and the loss of neurons and connections (amyloid plaques and neurofibrillary tangles).
The effect on retrieval. Autobiographical events are stored as episodic memories, which depend on the hippocampus and its connections to the neocortex for both consolidation and retrieval. As these structures deteriorate, the person can no longer access or reconstruct stored personal events, so retrieval of autobiographical memories is impaired (and forming new ones becomes very difficult).
Markers reward naming the hippocampus (and/or neocortex) and explicitly linking its damage to impaired retrieval of episodic, autobiographical memory.
2025 VCAA2 marksDescribe how evidence from brain imaging could provide data to track the progression of Alzheimer's disease.Show worked answer →
Two marks: state what brain imaging shows, and how repeated imaging tracks progression.
Brain-imaging techniques (such as MRI or PET) produce images of brain structure and/or activity. In Alzheimer's disease they can reveal shrinkage (atrophy) of structures such as the hippocampus, enlarged ventricles, and reduced activity or the build-up of amyloid plaques.
By imaging the same person at intervals over time and comparing the scans, researchers can measure the increasing loss of brain volume and activity. This change over time provides objective data that tracks how far the disease has progressed.
One mark for what imaging detects, one mark for using repeated and comparative imaging to track progression.
2023 VCAA1 marksDawes et al. (2022) compared 30 people who experience aphantasia with 30 control participants who did not, using a visual mental imagery questionnaire and an interview about past personal events and imagined future events. Which of the following results would most likely be found? A. Control participants are less likely to link implicit memories with mental imagery. B. Aphantasic participants reporting enhanced episodic detail compared to control participants. C. Aphantasic participants reporting lower mental imagery vividness compared to control participants. D. Control participants generating more semantic detail than aphantasic participants when imagining future events.Show worked answer →
Answer: C. This is a 1 mark multiple-choice item.
Aphantasia is the inability to generate voluntary mental imagery. By definition, people with aphantasia report lower vividness of visual mental imagery than control participants, so a questionnaire measuring imagery vividness would show this difference.
B is wrong because aphantasic participants typically report reduced episodic detail, not enhanced. A and D make claims (about implicit memory, and about semantic detail favouring controls) that are not the central, expected finding of the study, which is the difference in imagery vividness.