PS2111 CDL Lecture 3.pptx
Transcript
PS2111 Working memory Carlo De Lillo Sensory memory Perceptual systems store images for a short period Sensory memory Sperling 1960 BCXY NFRW TZKD –Brief presentation 12-letter matrix, then: –Full report 3-4 letters max –Partial report High tone – top row Medium tone - second row Low tone – third ro...
PS2111 Working memory Carlo De Lillo Sensory memory Perceptual systems store images for a short period Sensory memory Sperling 1960 BCXY NFRW TZKD –Brief presentation 12-letter matrix, then: –Full report 3-4 letters max –Partial report High tone – top row Medium tone - second row Low tone – third row Accurate report suggest that all 12 letters are stored in sensory memory Neisser 1967 –Iconic memory - Visual –Echoic memory – Auditory –Sensory stores Short term memory Retention of information over periods of a few seconds Limited capacity Typically measured by digit span 9754 – Serial recall 3825 – Requires item memory and order memory 94318 – Included in intelligence tests (e.g. WAIS)68269 913825 648371 Etc. Serial recall How is order remembered? Chaining –Each item associated with the next –Fails to explain ordered recall following missing items Context A B C D Changing context –Each items linked to a changing context which acts as recall cue –Context can be time A B C D Primacy –Each item receives activation at presentation –Most activation to first item (primacy) –Decreasing activation for second, third etc. –Once an items is recalled its activation is suppressed –Then next item with strongest activation is chosen etc. A BC D Strength Which is easier to recall? CTAILTCSFRO FRACTOLISTIC Chunking CTAILTCSFRO – Difficult to repeat back – Letters cannot be grouped into larger pronounceable units FRACTOLISTIC – Easier to repeat back – Letters can be grouped Chunking Can be induced by temporal separation of subgroups – 791-684 -352 easier to recall than 791684352 Process of combining several items into larger groups typically on the basis of LTM Miller 1956 – The magical number 7+/-2 – Memory capacity limited by chunks not individual items Free recall Repeat lists of items in any order – List length effect – Primacy effect – Recency effect Traditional models of STM Atkinson and Shiffrin 1968 Modal model of memory Problems of modal model Assumption of directional flow of information from STM to LTM Neuropsychological patient with STM deficits but able to learn (Shallice and Worrington 1970) Neuropsychological patients with STM deficits unimpaired in every day and professional tasks (e.g. secretary; taxi driver; shop keeper, Vallar and Shallice, 1990). Baddeley & Hitch 1974 Tested assumption that reasoning and learning are affected if WM is impaired Dual task methodology with healthy people Interfering secondary task should detract resources from primary task Baddeley & Hitch 1974 Grammatical reasoning test (main task) Digit span (to load WM) Reasoning delayed but not impaired by WM load Working Memory (WM) System enabling to hold information in mind when performing complex task (Miller et al. 1960; Atkinson and Shiffrin 1968) Original multicomponent model of WM (Baddeley & Hitch, 1974) Components of WM – Phonological loop – Visuo-spatial sketch pad – Central executive Phonological loop WM component responsible for temporary storage of speech like information – Two subcomponents – Short term store Rapid decay – Articulatory process Used for rehearsal Evidence for phonological loop Phonological similarity effect – Span reduced for similar sounding items (Conrad 1964) Cat, map, man, cap, mad (difficult) Pit, day, cow pen, hot (easy) – At short intervals Unaffected by word meaning Huge, big, great vs. thin, old, late – At long intervals Stronger effect of word meaning LTM semantic memory Articulatory suppression – Repeating a word aloud keeps articulatory process busy – Sub-vocal rehearsal blocked – Interference with verbal span tasks World length effect (Baddeley et al., 1975) – Word length correlated with reading speed – Long words take longer to rehearse – Negative correlation between word length and recall – People recall as many words as can be read in 2s (Baddeley et al., 1975) Visuo-spatial sketch pad Spatial memory span Corsi tapping test (Milner 1971) – Recall sequence of taps on blocks – Start with 3 and then increase sequence length – Typical span of 5 items – No interference with articulatory suppression – Interference with spatial task (e.g. pursuit rotor) Visuo-spatial sketchpad Visual memory span Measured with visual pattern span (Della Sala et al., 1999) Recall position of filled squares Start with 2 x 2 matrix Cell numbers increased up to 5 x6 Visuo-spatial distinction (Della Sala et al. 1999) Interference task in retention interval Visual -View irrelevant pictures during retention interval Spatial- Follow haptically a sequence of pegs on a Visuo-spatial sketchpad and imagery (Baddeley et al., 1973) The central executive Possibly most important component but not well characterised Supervisory Attention System (Norman & Shallice 1986) – Automatic conflict resolution (e.g. slowing down at red traffic light when driving) – SAS used when automatic processing conflict resolution not possible (e.g. road closed) – Conflict resolved or alternative solutions sought – Central executive as SAS Allocating attention Dividing attention between concurrent tasks Interfered by random letter generation The central executive Henson et al (1996) – Random letter generation impairs recall of chess positions – No effect of articulatory suppression or spatial tapping Baddeley et al (1991) – Alzheimer’s patients impaired in dual tasks (digit span and spatial tracking) – compared to performance on each task – compared to healthy young and elderly Problems with the original WM model Does not account for links with LTM – Prose recall much better (15 words) than unconnected word recall (6 words) and beyond capacity of phonological loop – Chunking Binding – How different sources of information are bound together Revised multi-component WM model (Baddeley 2000) Added new episodic buffer component Enables links between subcomponents and LTM Summary Sensory memory STM Serial order Modal model of memory Multicomponent model of WM Evidence for components of WM Revised multicomponent model of WM Reading Essential Baddeley, A. (2012). Working memory: Theories. Models and Controversies. Annual Review of Psychology, 6:1-29. Baddeley, Eysenk & Anderson. Memory. Psychology Press, 2014. Chapters 1 (pp. 8-12), 2 and 3. Additional Baddeley, A. (2003). Working memory: Looking Back and looking forward. Nature Reviews Neuroscience, 4:829-838. Eysenk and Keane Cognitive psychology, 2015 (7th Edition) Chapter 6, pp. 207-229
