The three types of forgetting
- Forgetting happens for more than one reason, and three explanations cover most of it.
- Decay, displacement and retrieval failure have separate causes.
- Decay and displacement destroy the information itself.
- Retrieval failure leaves the memory in long-term memory and blocks the route back to it.
Key Idea
- Forgetting has three separate causes, so the job in any scenario is deciding which one the detail points to.
- In decay and displacement the information itself has gone, and in retrieval failure it is still held in long-term memory with the route back to it blocked.
- That is why the right reminder can hand back a classmate's name, and no reminder will bring back French vocabulary that faded years ago.
How each type of forgetting works
Definition
Memory trace
The physical change left in the brain when a memory is stored. If the trace is not used or rehearsed, it can fade over time.
- Decay
- Storing a memory leaves a physical trace in the brain, built from strengthened connections between neurons.
- A trace that is not used or rehearsed weakens as time passes, until there is nothing left to find.
- The passage of time is the cause of decay.
- Displacement
- Short-term memory holds only about seven items at once.
- When the store is already full, a new item arriving needs space that is not there.
- An older item is pushed out before it can be rehearsed into long-term memory, so it is lost.
- Retrieval failure, or lack of cues
- The memory stays in long-term memory the whole time.
- It cannot be reached because the cues that were present during learning are missing now.
- Supplying the right cue brings the memory back, which shows it was still stored.
Example
- Decay: French vocabulary learned for a Year 8 test and never used again has faded by Year 11.
- Displacement: a friend reads out a new number across the common room, and holding it pushes out the one you were about to dial.
- Retrieval failure: a classmate's name sits on the tip of your tongue until someone mentions their football team, and the name comes back.
Cues and retrieval failure
Definition
Cue
A reminder or trigger that helps you find a stored memory, such as a place, a smell or a word. It can also be the surroundings or the mood you were in when the memory was first formed.
- A cue is a reminder that points to where a memory is stored, such as a place, a smell or a single word.
- Cues can be external, such as the room the material was revised in, or internal, such as the mood the person was in when they learned it.
- Picking the right answer from four options is easier than writing it on blank paper, because the options act as cues.
- A smell, a place or a single word can hand back a memory that seemed to have gone.
Common Mistake
- Decay is fading over time and displacement is being crowded out by new items, so the two are separate causes.
- Retrieval failure does not lose the memory, because it stays stored and the right cue brings it back.
- Short-term memory is a store rather than a type of forgetting.
Turning this into marks
- Name the type of forgetting and then quote the detail in the situation that decided it, because a type named on its own gains no application mark.
- Choose decay when time has passed with no new information arriving, displacement when new items crowded an older one out of a full short-term store, and retrieval failure when the right reminder would bring the memory straight back.
- Say that the memory is still stored when you write about retrieval failure, because that detail secures the knowledge mark.
- The mark most often lost is naming a memory store instead of a type of forgetting.
Self review
- Name the three types of forgetting.
- How does retrieval failure differ from decay?
- In displacement, why is the older item lost?
- Give one external cue and one internal cue.
- Which two types of forgetting destroy the information itself?
