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Chapter 5 Short-Term and Working Memory. Some Questions to Consider Why can we remember a telephone number long enough to place a call, but then we forget.

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Presentation on theme: "Chapter 5 Short-Term and Working Memory. Some Questions to Consider Why can we remember a telephone number long enough to place a call, but then we forget."— Presentation transcript:

1 Chapter 5 Short-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 Modal Model of Memory Atkinson and Shiffrin (1968) Computer as a model for human cognition Memory is an integrated system that processes information –Acquire, store, and retrieve information –Components of memory do not act in isolation Memory has a limited capacity –Limited space –Limited resources –Limited 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 Memory Control processes: active processes that can be controlled by the person –Rehearsal –Strategies used to make a stimulus more memorable –Strategies 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 receptors –Information decays very quickly Persistence of vision: retention of the perception of light –Sparkler’s trail of light –Frames in film

9 Modal Model of Memory: Sensory Memory Holds large amount of information for a short period of time –Collects information –Holds information for initial processing –Fills 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 screen –Participants 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 seen –Average 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 report –Average 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 extinguished –Performance decreases rapidly

14 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 duration Includes 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 memory –Read three letters, then a number –Begin counting backwards by three’s –After 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 memory –Digit span: how many digits a person can remember Typical result: 5-8 items But what is an item?

22 Modal Model of Memory: Short-Term Memory Chunking: small units can be combined into larger meaningful units –Chunk 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 chunking S.F. had an initial digit span of 7 –After 230 one-hour training sessions, S.F. could remember up to 79 digits Chunking them into meaningful units

24 Modal Model of Memory: Short-Term Memory Chase and Simon (1973) –Memory for chess pieces on a board –Chess masters and beginners –Pieces 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 represented –Physiological: how stimulus is represented by the firing of neurons –Mental: 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 down –Errors most often occurred with letters that sounded alike –STM is auditory

28 Modal Model of Memory: Short-Term Memory Visual coding – Della Sala (1999) –Presented visual information that is difficult to verbalize –Participants could recreate patterns of up to 9 items –STM 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 words Four trials, different words on each trial

30 Modal Model of Memory: Short-Term Memory On trial 4, participants memorized words from a different category –Release from PI: memory increased –Participants used meaning of the words in their processing –STM is also semantic

31 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 Memory Similar concept to short-term memory Working memory (WM): limited capacity system for temporary storage and manipulation of information for complex tasks such as comprehension, learning, and reasoning

33 Working Memory Working memory differs from STM –STM is a single component –WM consists of multiple parts

34 Working Memory Working memory differs from STM –STM holds information for a brief period of time –WM 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 Loop Phonological similarity effect –Letters or words that sound similar are confused

37 Phonological Loop Word-length effect –Memory for lists of words is better for short words than for long words –Takes longer to rehearse long words and to produce them during recall

38 Phonological Loop Articulatory suppression –Prevents one from rehearsing items to be remembered Reduces memory span Eliminates word-length effect Reduces phonological similarity effect for reading words

39 Visuospatial Sketch Pad Brooks (1968) –Memorize sentence and then consider each word (mentally) –Response is either Phonological: say “yes” if it is a noun and “no” if it is not Visuospatial: point to Y if word is a noun and N if word is not

40 Visuospatial Sketch Pad Pointing was easier than speaking Task (memorize sentence) involved the phonological loop Pointing response involved the visuospatial sketch pad Verbal response involved the phonological loop Conducting two verbal tasks overloaded the phonological loop

41 Visuospatial Sketch Pad Brooks (1968) –Visualize a capital letter F, starting at the top left corner –Response is either Phonological: say “out” if it is an exterior corner and “in” if it is an interior corner Visuospatial: 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 pointing Task (visualize a capital letter) involved the visuospatial sketch pad Pointing response involved the visuospatial sketch pad Verbal response involved the phonological loop Conducting 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 Memory WM is set up to process different types of information simultaneously WM has trouble when similar types of information are presented at the same time

45 The Central Executive Attention controller –Focus, divide, switch attention Controls suppression of irrelevant information

46 Episodic Buffer Backup store that communicates with LTM and WM components Hold 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 Brain Prefrontal cortex responsible for processing incoming visual and auditory information –Monkeys without a prefrontal cortex have difficulty holding information in WM

49 WM and the Brain Funahashi et al. (1989) –Single cell recordings from monkey’s prefrontal cortex during a delay-response task

50 WM and the Brain Neurons responded when stimulus was flashed in a particular location and during delay Information 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 Brain Areas 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’ WM –High-capacity WM group –Low-capacity WM group Shown either simple or complex stimuli Measured ERP responses

55 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) Results –High-capacity participants were more efficient at ignoring the distractors


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