Presentation on theme: "Short-Term and Working Memory"— Presentation transcript:
1 Short-Term and Working Memory Chapter 5Short-Term and Working Memory
2 Some Questions to Consider Why can we remember a telephone number long enough to place a call, but then we forget it almost immediately?Is there a way to increase the ability to remember things that have just happened?Do we use the same memory system to remember things we have seen and heard?Is there a relationship between memory capacity and intelligence?
3 What Is Memory?Memory: processes involved in retaining, retrieving, and using information about stimuli, images, events, ideas, and skills after the original information is no longer present
4 Atkinson and Shiffrin (1968) Computer as a model for human cognition Modal Model of MemoryAtkinson and Shiffrin (1968)Computer as a model for human cognitionMemory is an integrated system that processes informationAcquire, store, and retrieve informationComponents of memory do not act in isolationMemory has a limited capacityLimited spaceLimited resourcesLimited time
5 Caption: Flow diagram for Atkinson and Shiffrin’s (1968) model of memory. This model, which is described in the text, is called the modal model because of the huge influence it has had on memory research.
6 Modal Model of MemoryControl processes: active processes that can be controlled by the personRehearsalStrategies used to make a stimulus more memorableStrategies of attention
7 Caption: What happens in different parts of Rachel’s memory as she is (a and b) looking up the phone number, (c) calling the pizza shop, and (d) memorizing the number. A few days later, (e) she retrieves the number from long-term memory to order pizza again. Darkened parts of the modal model indicate which processes are activated for each action that Rachel takes.
8 Modal Model of Memory: Sensory Memory Short-lived sensory memory registers all or most information that hits our visual receptorsInformation decays very quicklyPersistence of vision: retention of the perception of lightSparkler’s trail of lightFrames in film
9 Modal Model of Memory: Sensory Memory Holds large amount of information for a short period of timeCollects informationHolds information for initial processingFills in in the blank
10 Modal Model of Memory: Sensory Memory Measuring the capacity and duration of sensory memory (Sperling, 1960)Array of letters flashed quickly on a screenParticipants asked to report as many as possible
11 Modal Model of Memory: Sensory Memory Whole report: participants asked to report as many as could be seenAverage of 4.5 out of 12 letters (37.5%)
12 Modal Model of Memory: Sensory Memory Partial report: participants heard tone that told them which row of letters to reportAverage of 3.3 out of 4 letters (82.5%)Participants could report any of the rows
13 Modal Model of Memory: Sensory Memory Delayed partial report: presentation of tone delayed for a fraction of a second after the letters were extinguishedPerformance decreases rapidly
14 Caption: Results of Sperling’s (1960) partial report experiments Caption: Results of Sperling’s (1960) partial report experiments. The decrease in performance is due to the rapid decay of iconic memory (sensory memory in the modal model).
15 Modal Model of Memory: Short-Term Memory Stores small amounts of information for a brief durationIncludes both new information received from the sensory stores and information recalled from long-term memory
16 Modal Model of Memory: Short-Term Memory Measuring the duration of short-term memoryRead three letters, then a numberBegin counting backwards by three’sAfter a set time, recall three letters
17 Modal Model of Memory: Short-Term Memory After three seconds of counting, participants performed at 80%After 18 seconds of counting, participants performed at 10%
18 Modal Model of Memory: Short-Term Memory Short-term memory, when rehearsal is prevented, is about seconds
19 Modal Model of Memory: Short-Term Memory Proactive interference (PI): occurs when information learned previously interferes with learning new information
20 Caption: Results of Peterson and Peterson’s (1959) duration of STM experiment. (a) The result originally presented by Peterson and Peterson, showing a large drop in memory for letters with a delay of 18 seconds between presentation and test. These data are based on the average performance over many trials. (b) Analysis of Peterson and Peterson’s results by Keppel and Underwood, showing little decrease in performance if only the first trial is included.
21 Modal Model of Memory: Short-Term Memory Capacity of short-term memoryDigit span: how many digits a person can rememberTypical result: 5-8 itemsBut what is an item?
22 Modal Model of Memory: Short-Term Memory Chunking: small units can be combined into larger meaningful unitsChunk is a collection of elements strongly associated with one another but weakly associated with elements in other chunks
23 Modal Model of Memory: Short-Term Memory Ericcson et al. (1989)Trained a college student with average memory ability to use chunkingS.F. had an initial digit span of 7After 230 one-hour training sessions, S.F. could remember up to 79 digitsChunking them into meaningful units
24 Modal Model of Memory: Short-Term Memory Chase and Simon (1973)Memory for chess pieces on a boardChess masters and beginnersPieces positioned for a real chess game or randomly positioned
25 Caption: Results of Chase and Simon’s (1973a, 1973b) chess memory experiment. (a) The chess master is better at reproducing actual game positions. (b) Master’s performance drops to level of beginner when pieces are arranged randomly.
26 Modal Model of Memory: Short-Term Memory How is information coded in STM?Coding: the way information is representedPhysiological: how stimulus is represented by the firing of neuronsMental: how stimulus or experience is represented in the mind
27 Modal Model of Memory: Short-Term Memory Auditory coding – Conrad (1964)Participants briefly saw target letters and were asked to write them downErrors most often occurred with letters that sounded alikeSTM is auditory
28 Modal Model of Memory: Short-Term Memory Visual coding – Della Sala (1999)Presented visual information that is difficult to verbalizeParticipants could recreate patterns of up to 9 itemsSTM is also visual
29 Modal Model of Memory: Short-Term Memory Semantic coding – Wickens et al. (1976)Participants listened to three words, counted backwards for 15 seconds, and attempted to recall the three wordsFour trials, different words on each trial
30 Modal Model of Memory: Short-Term Memory On trial 4, participants memorized words from a different categoryRelease from PI: memory increasedParticipants used meaning of the words in their processingSTM is also semantic
31 Caption: Results of Wickens et al Caption: Results of Wickens et al.’s (1976) proactive inhibition experiment. (a) Fruit group, showing reduced performance on trials 2, 3, and 4 caused at least partially by proactive interference (indicated by dark points). (b) Professions group, showing reduced performance on trials 2 and 3 but improved performance on trial 4. The increase in performance on trial 4 represents a release from proactive interference caused by the change of category from professions to fruits.
32 Working MemorySimilar concept to short-term memoryWorking memory (WM): limited capacity system for temporary storage and manipulation of information for complex tasks such as comprehension, learning, and reasoning
33 Working MemoryWorking memory differs from STMSTM is a single componentWM consists of multiple parts
34 Working MemoryWorking memory differs from STMSTM holds information for a brief period of timeWM is concerned with the processing and manipulation of information that occurs during complex cognition
35 Caption: Diagram of the three main components of Baddeley and Hitch’s (1974; Baddeley 2000) model of working memory: the phonological loop, the visuospatial sketch pad, and the central executive.
36 Phonological LoopPhonological similarity effectLetters or words that sound similar are confused
37 Phonological LoopWord-length effectMemory for lists of words is better for short words than for long wordsTakes longer to rehearse long words and to produce them during recall
38 Phonological LoopArticulatory suppressionPrevents one from rehearsing items to be rememberedReduces memory spanEliminates word-length effectReduces phonological similarity effect for reading words
39 Visuospatial Sketch Pad Brooks (1968)Memorize sentence and then consider each word (mentally)Response is eitherPhonological: say “yes” if it is a noun and “no” if it is notVisuospatial: point to Y if word is a noun and N if word is not
40 Visuospatial Sketch Pad Pointing was easier than speakingTask (memorize sentence) involved the phonological loopPointing response involved the visuospatial sketch padVerbal response involved the phonological loopConducting two verbal tasks overloaded the phonological loop
41 Visuospatial Sketch Pad Brooks (1968)Visualize a capital letter F, starting at the top left cornerResponse is eitherPhonological: say “out” if it is an exterior corner and “in” if it is an interior cornerVisuospatial: point to “out” if it is an exterior corner and “in” if it is an interior corner
42 Visuospatial Sketch Pad Speaking was easier than pointingTask (visualize a capital letter) involved the visuospatial sketch padPointing response involved the visuospatial sketch padVerbal response involved the phonological loopConducting two visuospatial tasks overloaded the visuospatial sketch pad
43 Visuospatial Sketch Pad Results show that if the task and the response draw on the same WM component, performance is worse than if the task and the response are distributed between WM components
44 Working MemoryWM is set up to process different types of information simultaneouslyWM has trouble when similar types of information are presented at the same time
45 The Central ExecutiveAttention controllerFocus, divide, switch attentionControls suppression of irrelevant information
46 Episodic BufferBackup store that communicates with LTM and WM componentsHold information longer and has greater capacity than phonological loop or visuospatial sketch pad
47 Caption: Baddeley’s revised working memory model, which contains the original three components plus the episodic buffer.
48 WM and the BrainPrefrontal cortex responsible for processing incoming visual and auditory informationMonkeys without a prefrontal cortex have difficulty holding information in WM
49 WM and the BrainFunahashi et al. (1989)Single cell recordings from monkey’s prefrontal cortex during a delay-response task
50 WM and the BrainNeurons responded when stimulus was flashed in a particular location and during delayInformation remains available via these neurons for as long as they continue firing
51 Caption: Results of an experiment showing the response of neurons in the monkey’s PF cortex during an attentional task. Neural responding is indicated by an asterisk (*). (a) A cue square is flashed at a particular position, causing the neuron to respond. (b) The square goes off , but the neuron continues to respond during the delay. (c) The fixation X goes off , and the monkey demonstrates its memory for the location of the square by moving its eyes to where the square was
52 WM and the BrainAreas in frontal lobe, parietal lobe, and cerebellum are involved in WM
53 Caption: Some of the areas in the cortex that have been shown by brain imaging research to be involved in working memory. The colored dots represent the results of more than 60 experiments that tested working memory for words and numbers (red), objects (blue), spatial location (orange), and problem-solving (green).
54 WM and the Brain: Individual Differences Vogel et al. (2005)Determined participants’ WMHigh-capacity WM groupLow-capacity WM groupShown either simple or complex stimuliMeasured ERP responses
55 Caption: Results of the Vogel et al. (2005) experiment Caption: Results of the Vogel et al. (2005) experiment. The key finding is that performance is about the same when only the red rectangles are present (left pair of bars); although adding the two blue rectangles has little effect for the high-capacity participants, it causes an increase in the response for the low-capacity participants (right pair of bars).
56 WM and the Brain: Individual Differences Vogel et al. (2005)ResultsHigh-capacity participants were more efficient at ignoring the distractors