THE “WORKING MEMORY” APPROACH

THE “WORKING MEMORY” APPROACH • Baddeley & Hitch (1974) • Use articulatory suppression to interfere with some tasks, not othersB doesn’t precede A B A • Develop “Working Memory” model: • Desk-top metaphor for STM • Process & storage tradeoff • (e.g., Posner & Rossman 1965) • Multicomponent structure

COMPONENTS OF WORKING MEMORY(Baddeley, 1990) (Random letter generation) Central executive (attentional control) Phonological store Visual-spatial sketchpad (Repetitive articulation) (Repetitive keying)

Concurrent Articulation and the Phonological Store (Peterson & Johnson, 1971)

WORKING MEMORY AND CHESS (Robbins, 1996) Primary task:recall of chess piece positions Secondary tasks: N None P articulate “the, the..” V execute 4x4 key pattern CE generate random letters Mean correct recall NP V CE

M P + F P + DISSOCIATING THE SKETCHPAD FROM THE LOOP • Instances of selective interference (e.g., Brooks, 1968) • Imaging evidence (Jonides, 1995) • The n-back task2-back: verbal: match letter identitySpatial: match location of dot in array Dorsolateral Prefrontal lights up: • Left side for verbal task • Right side for spatial task

Prefrontal Activity Varies with Memory Demand Rypma, et al. (2002) 1, 3 or 6 letters in memory set

Low memory-demand activity limited to Ventrolateral Prefrontal Cortex • High memory-demand also activates Dorsolateral Prefrontal cortex • Differences are largest for high-performance subjects

WM ACTIVITY and LTM ENCODING • Greater fMRI activity during WM trial correlated with: • better WM performance (Pessoa, et al. 2002 • Memory load for good performers (Rypma, et a., 2002) • Better subsequent LTM (Brewer, et al. 1988) • Integrative WM tasks (e.g., item x location) correlated with: • Greater “remember” judgments • Specific areas of “coupling” of PFC and other cortical areas • Greater memory-contingent PFC effect for associative than item memory (Howland, 2005) • Baddeley’s “Episodic Buffer”?

WORKING MEMORY SPAN AND COGNITIVE PERFORMANCE • Daneman & Carpenter (1980) • Reading Span, not digit span, correlates with reading comprehensionThe witness examined by the attorney…The evidence examined by the attorney… • Engle et al. (1995) • Develop other “spans” (Operation Span) • Argue it’s not “capacity” but skill at controlling tasks and codes, inhibition, etc. • James’ “span of consciousness?”

Some Baddeley & Hitch 1974 trials Repeat 2,5,8,3 rapidly A doesn’t follow B A B D precedes G G D X follows Y X Y N doesn’t precede R R N

Posner & Rossman 65Demonstration • Set 1: write down last two digits, and add one ARAP, e.g. 91/92/93 • 2 6 4 5 7 3 8 1 • 7 5 2 4 8 6 1 9 • 1 3 2 4 5 7 6 8 • Set 2: write down last two digits, and subtract 3 ARAP e.g. 91/88/85 • 5 4 7 2 3 1 6 9 • 7 1 2 8 9 4 3 5 • 6 5 3 8 2 1 4 7should be greater errors in Set 2, as difficulty of “work” in WM makes storage/refreshing of PL harder

N-back demo • 0-back series (target is “S” • E D T W S V D D S G H R S • 1-BACK (REPETITION) • N K Q Q F T L C C W T S S Q • 2-BACK (LAG OF 2) • Q X F X W T T W T J L J N

THE “WORKING MEMORY” APPROACH