1.5 coding, capacity, duration in STM + LTM

what does coding mean in memory?

coding is the way information is stored in memory — either acoustically, visually or semantically.

what did baddeley (1966) find about coding in STM and LTM?

he gave participants word lists that were acoustically or semantically similar.

• stm: confused similar-sounding words → coded acoustically.

• ltm: confused similar-meaning words → coded semantically.

what does capacity mean in memory?

is how much information can be held in memory at one time.

what did konkle do for ltm capacity

• participants were shown 2900 images at once for 3s

• recognition test of 2 image (one new one old) and was asked what was seen earlier

• 96% accuracy recall

what did jacobs (1887) find about stm capacity?

used a digit span test, then later asked to recall

average span: 9.3 for numbers, 7.3 for letters.

stm has a limited capacity of around 7 ± 2 items. (MILLER 1957)

what did miller (1956) find about stm capacity?

found stm can hold 7 ± 2 chunks of information — known as the “magic number 7”.

people can increase capacity by chunking information.

evaluate baddeley’s research on coding

✔ showed clear difference between stm and ltm coding.

❌ used artificial material (word lists) — lacks realism.

❌ real-life memories may use semantic coding even in stm.

evaluate jacobs and miller’s studies on capacity.

✔ research supports stm is limited.

❌ old studies — lack control and standardisation.

❌ capacity may vary depending on age and strategy use.

what does duration mean in memory?

duration is how long information can stay in a memory store before being forgotten.

what did peterson and peterson (1959) find about stm duration?

• participants remembered trigrams while counting backwards to stop rehearsal.

• after 3 seconds: 80% recall. after 18 seconds: <10% recall.

• stm duration is about 18–30 seconds without rehearsal.

evaluate peterson and peterson’s study on duration.

✔ high control, reliable procedure.

❌ artificial task (trigrams), low ecological validity.

❌ may have tested displacement, not decay.

what did bahrick et al. (1975) find about ltm duration?

• tested 392 american graduate (17-74) on high school yearbooks.

• after 15 years: 90% accuracy (photo recognition).

• after 48 years: 70% accuracy.

• without cues: 15 years: 60%, 48 years: 30%

LTM can last a lifetime.

evaluate bahrick et al.’s study on ltm duration.

✔ high ecological validity, real-life memories.

✔ large sample, reliable results.

❌ confounding variables — participants may have rehearsed memories.

summarise differences between stm and ltm.

feature	stm	ltm
coding	acoustic	semantic
capacity	7 ± 2 items	unlimited
duration	18-30 seconds	lifetime

what did clive wearing and hm show about stm and ltm? (AO3)

strength; both had damaged ltm but normal stm, showing stm and ltm are separate stores, supporting the multi-store model.

strength: murdock

participants were given word lists and were presented one at a time (1-2s) then recalled afterwards.

found primary and recency effect, middle words were recalled poorly → supports LTM (RE) and STM (PE)

weakness: craik & tulving

test the process, not rehearsal determines memory.

• MSM claims that rehearsal is what transfers information from STM → LTM.

• Craik & Tulving show that what matters more is depth of processing, not rehearsal.

• Even without rehearsal, semantically processed words were remembered best.

how does rehearsal affect memory transfer?

maintenance rehearsal keeps info in stm, prolonged rehearsal moves it to ltm. this links to the multi-store model by atkinson and shiffrin (1968).