Memory and Forgetting
You must know the stage model, its capacity and duration figures, the methods used to measure retention, and the several distinct causes of forgetting. Answers often hinge on correctly naming the type of interference.
Stage model (Atkinson–Shiffrin)
- Encoding → storage → retrieval.
- Sensory memory: iconic (under 1 second), echoic (2–3 seconds), large capacity.
- Short-term memory: about 18–30 seconds without rehearsal; capacity 7 ± 2 chunks; chunking expands effective capacity.
- Long-term memory: declarative (episodic events, semantic facts) and non-declarative (procedural skills).
- Working memory (Baddeley): phonological loop, visuospatial sketchpad, central executive.
- Levels of processing: semantic (deep) encoding yields better retention than rote repetition.
Measuring memory
- Recall, recognition and relearning (savings score); recognition is the easiest.
- Ebbinghaus's forgetting curve: steep initial loss, then a flattening tail.
Forgetting
- Trace decay; interference - proactive (old disrupts new) and retroactive (new disrupts old); retrieval failure (tip-of-the-tongue); motivated forgetting (repression); encoding failure; consolidation failure in amnesia (retrograde versus anterograde).
- Improvement: mnemonics, method of loci, organisation, spaced practice, overlearning, SQ3R.
Worked example
You save a new phone number, but when you try to recall it the old number keeps surfacing. The previously learned material is interfering with retrieval of the newer material - proactive interference. If the new number blocked out the old one, that would be retroactive interference.
Traps
- Short-term memory is not unlimited; 7 ± 2 items, not 7 ± 3.
- Proactive means forward (old affects new).
- Recognition and recall are different measures; recognition is easier.