Short Term Memory• William James (1900): Made Primary-Secondary memory

distinction. Important distinction: Primary was limited capacity and duration. Secondary more permanent.

• George Miller: Magical #7 (1956). Emphasized the importance of recoding or chunking of information.

• Brown-Peterson task: test of duration of STMTrigram: KNP; 517; backwards by 3 from number for variable amount of time, by 15-18 seconds trigram gone

Decay or Interference? • Brown-Peterson studies suggest that it might be delay that leads to loss in STM• Waugh and Norman disagreed, argued that verbal repetition of numbers may have

constituted interference effects. • Waugh/Norman (1965) study: decay vs. interference.List of numbers presented: 7 9 5 1 2 9 3 8 6 4 3 7 2 (tone)Tone marks repeated number; must recall number coming after repeated number first time

(answer: 9)Two variables: rate of presentation: (1/sec; 4/sec)Number of intervening items (1-13)If decay then rate should be criticalIf interference then number of itemsNo effect of rate; significant effect of items. Conclusion: Far stronger effect of interference

than decayTwo forms of interference: Retroactive: newer blocks older (present in WN study)Proactive: older blocks newer

Wickens Release from PI:

forgetting due to build up of semantic proactive interference items– distracter-recall; same category items -distracter-recall; same category items distracter-recall; then switch (for experimental group).

STM/LTM distinction: Serial Order Effect

Primacy: rehearsal allows for encoding into LTMRecency: still present in STM

Delay before recall affects recency but not primacy part of the effect

Searching STM: Sternberg Paradigm

Sternberg TaskSearch set (1-6 items); Comparison item; yes/no part of set?Ex: K X G D (G=yes) (F=no)RT’s increase linearly with set size; RT for yes and no equal. Serial/Exhaustive search.

Baddeley’s Model of Working memory

Brain anatomy of WM: Dorsolateral Pre-frontal Cortex: CEBroca’s area and left parietal: PLOccipital and posterior parietal: VSSP

PL: phonological store + articulatory loopArticulatory suppression effect: talking suppresses memoryPhono similarity effect: similar sounding words harder to remember than dissimilar

VSSP: Mental rotation studies

Farther apart pairs are from similar orientation the longer the reaction time. Longer rotations take more time

Episodic buffer: putting it all together

• EB: binds info from other systems together to form meaningful memories. • Dual task robs resources from non-meaningful processing not meaningful• Jefferies, Lambdon, Ralph and Baddeley (2004)• Subs learned unrelated words or sentences or meaningful sentences that formed a story• When secondary task applied (monitoring computer screen for form), performance on non-

meaningful conditions declined, but not on meaningful sentence condition• Ability of EB to use meaning for bind memories allowed for excess resources in meaningful sentence

condition, but resources in non-meaningful conditions all used up trying to recode word/sentences.

Selective interference: Dual task studies in WM

• Rationale: if PL and VSSP are truly separate systems then loading two tasks into one should cause a greater decrement in performance than spreading two tasks across two systems (one in each).

• Task 1: either letter span (PL) or image span (VSSP)• Task 2: either adding (PL) or imaging (VSSP)

Measuring WM capacity: WM spanRequires both processing and storageEx: 6x2-2=10? SPOT5x3-2=12? TRAIL3x2-4=2? BRANDCorrect response: y,n,y SPOT, TRAIL, BRAND WMS=3Increased WMS associated with:Less distractibility: less likely to hear name in unattended channel in dichotic listening testBetter filtering of irrelevant details when processing textMore consistent responses on moral reasoning tests (consistent moral principle applied across different dilemmas for high span subjects)Word fluency: better able to retrieve category-relevant words from memory