STM and WM Lecture (3) PDF

Short-Term & Working Memory CO G N I T IVE P S YCH OLOGY WEEK 4 DR É A DA O I N S LAT T E RY Some Questions to Consider Why can we remember a telephone number long enough to place a call, but then we forget it almost immediately? How is memory involved in processes such as doing a math problem? Do w...

Short-Term & Working Memory CO G N I T IVE P S YCH OLOGY WEEK 4 DR É A DA O I N S LAT T E RY Some Questions to Consider Why can we remember a telephone number long enough to place a call, but then we forget it almost immediately? How is memory involved in processes such as doing a math problem? Do we use the same memory system to remember things we have seen and things we have heard? 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. Active any time some past experience has an impact on how you think or behave now or in the future. Modal Model of Memory (1) Atkinson and Shiffrin (1968) Memory types: – Sensory memory—initial stage that holds all incoming information for seconds or fractions of a second – Short-term memory—holds five to seven items for about 15 to 20 seconds. – Long-term memory—can hold a large amount of information for years or even decades Modal Model of Memory (2) Atkinson and Shiffrin’s (1968) modal model of memory. Contains features of many of the memory models that were being proposed in the1960s. Sensory, short-term and long-term memory called structural features. Modal Model of Memory (3) Control processes: Active processes that can be controlled by the person. – Rehearsal – Strategies used to make a stimulus more memorable – Strategies of attention that help you focus on specific stimuli Modal Model: Storage and Retrieval What happens in different parts of Rachel’s memory as she is: (a, b) looking up the phone number, (c) calling the pizza shop, and (d) memorising the number. A few days later, (e) she retrieves the number from long-term memory to order pizza again. The parts of the modal model that are outlined in red indicate which processes are activated for each action that Rachel takes. Modal Model of Memory: Sensory Memory (1) Sensory memory: retention, for brief periods of time, of the effects of sensory stimulation. – Information decays very quickly. Persistence of vision: retention of the perception of light – Trail of light from a moving sparkler – Frames in film Modal Model of Memory: Sensory Memory (2) 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 Whole report method: participants asked to report as many as could be seen – Average of 4.5 out of 12 letters (37.5%) Modal Model of Memory: Sensory Memory (3) Partial report method: Participants heard tone that told them which row of letters to report. – Average of 3.3 out of 4 letters (82%) – Participants could report any of the rows Delayed partial report method: Presentation of tone delayed for a fraction of a second after the letters were extinguished – Performance decreases rapidly. Modal Model of Memory: Sensory Memory (4) 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). Modal Model of Memory: Sensory Memory (5) Iconic memory: brief sensory memory of the things that we see – Responsible for persistence of vision. Echoic memory: brief sensory memory of the things that we hear – Responsible for persistence of sound. Modal Model of Memory: Short-Term Memory (STM) (1) Stores small amounts of information for a brief duration. Includes new information received from the sensory stores and information recalled from long-term memory. Modal Model of Memory: Short-Term Memory (2) Measuring duration of short-term memory – Read three letters, then a three-digit number – Begin counting backwards by Threes – After a set time, recall three letters After 3 seconds of counting, participants performed at 80% After 18 seconds of counting, participants performed at 10% Reduction in performance explained by decay, the vanishing of a memory trace due to the passage of time and exposure to competing stimuli. Modal Model of Memory: Short-Term Memory (3) Capacity of short-term memory – Digit span: how many digits a person can remember ▪ Typical result: five to eight items ▪ Last 15 to 20 seconds or less ▪ But what is an item? 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. Increases capacity for STM. Modal Model of Memory: Short-Term Memory (4) Ericsson and coworkers (1980) – Trained a college student with average memory ability to use chunking ▪ – After 230 one-hour training sessions, student could remember up to 79 digits ▪ Student had initial digit span of 7 Chunking them into meaningful units Alvarez and Cavanagh (2004) – Memory capacity = “Amount of information” rather than number of items. – Used colored squares as well as complex objects – Used the change detection procedure Modal Model of Memory: Short-Term Memory (5) (a) Some of the stimuli used in Alvarez and Cavanagh’s (2004) change detection experiment. The stimuli range from low information (colored squares) to high information (cubes). In the actual experiments, there were six different objects in each set. (b) Results showing the average number of objects that could be remembered for each type of stimulus. Based on: Alvarez, G. A. and Cavanagh, P. (2004). The capacity of visual short-term memory is set both by visual information load and by number of objects, Psychological Science, 15, 106–111. Working Memory (1) Baddeley and Hitch (1974) Working memory: – Limited-capacity system for temporary storage and manipulation of information for complex tasks such as comprehension, learning, and reasoning. Working memory differs from short-term memory (STM) – STM holds information for a brief period of time – WM is concerned with the storage, processing and manipulation of information, and is active during complex cognition. Working Memory (2) Hitch’s (1974; Baddeley, 2000) model of working memory: - The phonological loop, - The visuospatial sketch pad, and the - Central executive. Working Memory (3) Working memory is set up to process different types of information simultaneously. Has trouble when similar types of information are presented at the same time. Phonological loop (1) Two components: - Phonological store: Limited capacity; only holds information for few seconds. - Articulatory rehearsal process: Responsible for rehearsal that keeps in phonological loop from decaying. Phonological Loop (2) Phonological similarity effect – Letters or words that sound similar are confused. 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. Phonological Loop (3) Articulatory suppression – Speaking prevents one from rehearsing items to be remembered ▪ Reduces memory span ▪ Eliminates word length effect ▪ Reduces phonological similarity effect for reading words. Visuospatial Sketch Pad Creation of visual images in the mind in the absence of a physical visual stimulus – Shepard and Metzler (1971): Mental rotation task – Result: Tasks that called for greater rotations in the mind, took longer. Stimuli for the “Comparing Objects” demonstration. See book for details. Based on: Shepard, R. N. and Metzler, J. (1971). Mental rotation of three-dimensional objects. Science, 171, Figures 1a & b, 701–703. The Central Executive Acts as the attention controller – Focus, divide, switch attention. Controls suppression of irrelevant information. Perseveration: repeatedly performing the same action or thought even if it is not achieving the desired goal. The Episodic Buffer (1) Backup store that communicates with long-term and working memory components. Hold information longer and has greater capacity than phonological loop or visuospatial sketch pad. The Episodic Buffer (2) Baddeley’s revised working memory model, which contains the original three components plus the episodic buffer. Source: Baddeley, A. D., Eysenck, M. and Anderson, M. C. (2009). Memory. New York: Psychology Press. Working Memory and the Brain (1) Prefrontal cortex responsible for processing incoming visual and auditory information. – Monkeys without a prefrontal cortex have difficulty holding information in working memory. Funahashi and coworkers (1989) – Single cell recordings from monkey’s prefrontal cortex during a delayed-response task. Working Memory and the Brain (2) Experiment showing the response of neurons in the monkey’s prefrontal 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. Adapted from: Funahashi, S., Bruce, C. J. and Goldman-Rakic, P. S. (1989). Mnemonic coding of visual space in the primate dorsolateral prefrontal cortex, Journal of Neurophysiology 61, 331–349, APA, adapted with permission. (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. Working Memory and the Brain (3) 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. Working Memory & Learn to Read Alphabetic decoding places great demands on children’s WM. Convert letters to sounds and store in mind WM is also involved in reading comprehension Store text in mind while manipulating words to understand the content. Working memory uniquely predicts word reading and reading comprehension (Slattery et al., 2021). Support Your Learning See the short videos below, that speak about some of the key elements from this week: The multistore Model of Memory https://www.youtube.com/watch?v=egzvLaP3498 Test yourself on this chapter Describe Atkinson and Shiffrin’s modal model of memory both in terms of its structure and control processes. Describe an example of a change detection experiment. What is an episodic buffer? Why was it proposed and what are its functions? Describe Baddeley’s working memory model.