Information Processing, Forgetting and the Brain
Memory as Information Processing
Psychologists explain memory as a system for processing information, much like a computer processes data. Information passes through five stages: input, encoding, storage, retrieval and output. Input is when information first reaches the senses — for example, hearing a new phone number. If any one of these five stages breaks down, the information cannot be successfully remembered and used later. This sequence explains why some information sticks and other information seems to disappear almost immediately — it depends on which stage succeeds or fails.
The five stages of information processing are: input (information reaches the senses), encoding (it is converted into a storable form), storage (it is held in the memory system), retrieval (it is accessed again) and output (it is used, spoken or acted on).
Encoding, Storage and Retrieval
Encoding is the process of changing raw information into a form the memory system can hold. This can happen visually (as an image), acoustically (as a sound) or semantically (by meaning). Remembering a new phone number by picturing the digits is visual encoding, while remembering it by its rhythm when spoken aloud is acoustic encoding. Shallow, surface-level encoding, such as repeating a number without thinking about what it means, tends to fade quickly, whereas linking new information to something already known produces a much more durable memory.
Storage keeps that encoded information over time, ready to be used later. Retrieval is the process of accessing that stored information, so it can be output — for example, saying the phone number aloud. All three processes must work correctly for a memory to be usable; a fault at any stage causes forgetting.
Information that has been encoded and stored can still be hard to bring back out. Retrieval often depends on a retrieval cue. Without the right cue, stored information can feel completely lost, even though it has not actually decayed or been displaced. This shows that forgetting is not always about memories disappearing — sometimes they are simply hard to reach.
Types of Forgetting
The specification identifies three named types of forgetting. Each describes a different reason why stored information cannot be output.
Decay happens when a memory trace naturally fades if it is not used or retrieved for a long period — the physical trace in the brain weakens over time.
Displacement happens when a memory store has limited capacity. New information coming in pushes out older information, which is then lost completely from that store.
Retrieval failure happens when information is still stored but cannot be accessed because the correct cue is missing. This differs from decay and displacement because the memory has not actually disappeared — it is simply inaccessible without the right trigger.
Decay is the fading of a memory trace over time. Displacement is new information pushing out old information in a limited-capacity store. Retrieval failure is when a stored memory cannot be accessed because the right cue is missing.
The Brain and Memory Formation
Memory is not just a mental process — it depends on specific structures in the brain. Neurological damage to different areas produces different, predictable memory problems, which is strong evidence that memory relies on distinct brain systems rather than one general area. This is one reason case studies of brain-damaged patients are so valuable in psychology — they show which mental abilities survive and which are lost when a specific area is affected.
Damage to the hippocampus is linked to anterograde amnesia. A person with this condition cannot form new long-term memories after their injury, even though memories from before the damage may still be clear.
Damage to the frontal lobe is linked to retrograde amnesia. Memories formed before the injury are lost, while the ability to form new memories afterwards can remain relatively unaffected.
A third structure, the cerebellum, plays a key role in procedural memory — memory for learned skills such as riding a bike. Damage to the cerebellum can disrupt the ability to learn or perform these automatic, skill-based memories, even when other types of memory are unaffected.
The clearest way to keep these apart is direction in time relative to the injury. Anterograde amnesia (hippocampus damage) blocks memories moving forwards — new memories cannot be formed after the damage. Retrograde amnesia (frontal lobe damage) blocks memories moving backwards — memories from before the damage are lost. Some patients with severe brain damage show both patterns at once.
The link between specific brain damage and specific memory problems can be examined in isolation in the exam, separately from the wider theory it supports. Learn the brain-area-to-memory-problem links as standalone facts, not only as part of a bigger explanation. Content separated by a semicolon in the specification, such as the different types of forgetting, can also be tested individually or in any combination, so make sure each type is understood on its own.