Prof. Greg Francis 1/2/12 PSY 200: Intro. to Cognitive Psychology 1 Purdue University Working memory PSY 200 Greg Francis Lecture 17 A problem with IQ tests. Purdue University Working memory  Current thought, awareness  extension of short-term memory  small capacity  rapid forgetting  Processor of information  not a storage device  hypothesizes mechanisms that lead to memory properties Central executive Visuo- spatial sketchpad Phonological loop Purdue University Phonological loop  Two components  Articulatory control process (ACP) » converts non-speech information into speech code » rehearsal / refresh  Phonological store (PS) » similar to how we first described STM (items decay from memory) » Refresh restarts the decay process ACP PS Phonological loop Purdue University ACP PS Phonological loop Loop capacity  How many items can be kept in the phonological loop?  Depends on two factors  Duration before decay from PS  Speed of rehearsal  Spinning coins! Purdue University Magic number?  We earlier noted that memory span was about 7 items (+/- 2)  The phonological loop suggests that it is not the number of items but their rehearsal duration  To recall a list of items you must rehearse them all before any of them fade  The duration of decay in the PS  Memory span should follow the equation  Span = (Rehearsal Rate) X (PS decay time)  Measure memory span (s): around 7 items  Measure verbal rehearsal rate (r): around 4 items per second for English speakers  Estimate duration of decay in PS (d)  d=1.75 seconds Purdue University Effect of rehearsal rate  Capacity of the phonological loop depends on the rate of rehearsal (r)  A set of items that takes longer to rehearse should be harder to remember  more likely that some items will drop out before you get back to the first item ACP PS Phonological loopProf. Greg Francis 1/2/12 PSY 200: Intro. to Cognitive Psychology 2 Purdue University Effect of rehearsal rate  Explains differences across groups of people  Age effects in children  Hitch, Halliday & Littler (1989)  This implies that it is not the loop size that changes with age, but the rate of rehearsal Span=1.68(Oral Reading Rate)+0.71 Purdue University Word length effect  Memory span is related to the length of words  Number of syllables  Nicely matched by changes in reading speed  Rate of rehearsal Purdue University Language effects  Some languages are spoken more quickly than others  Should allow larger memory span  it does Purdue University Relation to IQ  Ellis & Henley (1980)  investigated complaints about WISC intelligence scores  Welsch children tended to score lower than English children  Part of the exam checks memory span  and the slower rate of speech in Welsch partly explains the difference  bilingual Welsch students tested in English got better scores than when tested in Welsch Purdue University Articulatory suppression  Subjects sees (hears) a list of phonemes  Also repeats a phrase over and over  e.g., “tippy-toe, tippy-toe, tippy-toe,...  Recall is worse  True for both auditory and visual presentation  (Recall for visual may be better than auditory because there is some information in the visuospatial sketchpad as well) 00.10.20.30.40.50.60.70.80.91Visual AuditorySilentSuppressionProportion recalled Purdue University Articulatory suppression  Repeating phrase ties up the ACP  Without rehearsal more forgetting occurs ACP PS Phonological loop Visual tippy-toe AuditoryProf. Greg Francis 1/2/12 PSY 200: Intro. to Cognitive Psychology 3 Purdue University Phonological similarity  Memory of a list of items is worse when the items sound the same Better recall Worse recall B F H N B G P T Purdue University Phonological similarity  All items are stored in phonological loop  similar sounding items interfere with each other in the phonological loop  two possibilities: » 1) harder to rehearse (effect in the ACP) » 2) fade more quickly (effect in the PS) ACP PS Phonological loop B G P T ACP PS Phonological loop B F H N Purdue University Phonological similarity  All items are stored in phonological loop  similar sounding items interfere with each other in the phonological loop  two possibilities: » 1) harder to rehearse (effect in the ACP) » 2) fade more quickly (effect in the PS) ACP PS Phonological loop B G P T ACP PS Phonological loop B F H N Purdue University Locus of similarity effect  Studies find a phonological similarity effect for auditory stimuli under articulatory suppression  We suggested two possibilities: » 1) harder to rehearse (effect in the ACP) » 2) fade more quickly (effect in the PS)  Since the phonological similarity effect is there even when the ACP is not involved, it must be possibility 2 (in the PS) Proportion recalled Purdue University CogLab data  The CogLab experiment on memory span shows data in agreement with our expectations (205 subjects)  Item type Final list length  Numbers ! !!6.54! Letters that sound different !5.87! Letters that sound similar !5.17! Short words ! !!5.16! Long words ! !!4.19 About 7 Phonological similarity effect Word length effect Purdue University Irrelevant speech effect  Does irrelevant “background” sound affect memory?  E.g., studying with the TV on  Three groups of subjects recall consonants  1) no background  2) background = nonsense words  3) background = noise bursts best worstProf. Greg Francis 1/2/12 PSY 200: Intro. to Cognitive Psychology 4 Purdue University Irrelevant speech effect  The presence of phonemes in the background is critical to the effect  strong effect when background is spoken in German, even for English speakers  Suggests that background phonemes interfere in the PS  Study with classical music if you need something! Purdue University Visuospatial sketchpad  Briefly holds visual and spatial information  Important for tasks that require interaction with the environment or searching  Properties seem to vary across individuals  VSS of video gamers differs