Week 06 Sensory, Short-Term, and Working Memory PSYC 221 Lecture Notes PDF

Week 06 Sensory, Short-Term, and Working Memory PSYC 221  Learning Objectives Define basic processes of memory Describe the primary components of the Modal Model of Memory Identify duration and capacity of sensory and short-term memory, including...

Week 06 Sensory, Short-Term, and Working Memory PSYC 221  Learning Objectives Define basic processes of memory Describe the primary components of the Modal Model of Memory Identify duration and capacity of sensory and short-term memory, including how we study this and what affects duration and capacity Differentiate types of interference that lead to forgetting Describe the Working Memory Model and how it modifies the Modal Model of Memory Explain how information is coded in working memory  Outline Defining memory and the Modal Model Sensory Memory Short-term Memory The Working Memory addition  What is memory? Basic definition: Process where we use information from the past to generate/support cognitive functions in the present I thought the main character was really smart… I agree with Jo Jo because… I found the Mo main character annoying… Po  Three basic mechanisms of memory Encoding: Translation of information into a neural code that can be understood/represented in the brain Early Storage: Retention of the encoded information Varied length of time Retrieval: Recovering/finding the encoded, stored information for use in behaviour/cognition  Modal Model of Memory Major approach to understanding the organisation of memory Information processing approach: Brain actively manipulates information and processes it Humans are not passive receivers of information 3 components of memory in the modal model: 1) Sensory memory 2) Short-term memory (STM) 3) Long-term memory (LTM) Information flow in the Modal Model Atkinson & Shiffrin (1968)  Outline Defining memory and the Modal Model Sensory Memory Short-term Memory The Working Memory addition  Sensory memory: What is it? “Sensory echo” or “sensory trace” Capacity: High Not all goes into STM Duration: Very brief (order of milliseconds) Example: Persistence of vision Demonstrating Persistence of Vision Thermatrope Sensory memory exists in different sensory modalities Iconic memory: Echoic memory: Visual signals Auditory signals persist persist  Testing Iconic Memory: Methods Question: How much info do we glean from a single glance? A T R O Q M S B V N Z E What letters did you see? Sperling (1960)  Testing Iconic Memory: Results On average, people report 4-5 letters (out of 12) Claimed that they had actually seen the whole array, but “forgot” it while reporting Claimed array seemed to fade but was available to examine mentally even after it went off the screen, for a brief period of time Sperling (1960)  Testing Iconic Memory: Follow-Up Experiment “Partial report” procedure: Participants report a specific row of letters in the array Crucial manipulation: A cue (tone) is played to the participants after they see the display Cue (tone) indicates which row to report Why does this matter? -> briefly retain image of the array in your head, then report the letters Sperling (1960)  Sperling (1960): Testing Iconic Memory: Follow-Up Results 10 Optimal 100% # of Letters Reported 8 Partial report ~ 80% 6 4 Whole report ~ 25- 35% 2 2 4 6 8 10 12 # of Letters Displayed  Sperling (1960): Testing Iconic Memory Take away We can hold quite a bit of information in sensory memory But… We must apply attention to select it out and use it  Duration of Sensory Memory Question: How long is information maintained in visual sensory memory (iconic memory)? Sperling (1960) varied the time delay of the partial report cue after the letter display. Compared partial report to whole report (with no delay) Duration of Sensory Memory Describe the pattern you see in the data Duration and Capacity interact  Duration of Sensory Memory: Take away Duration and Capacity interact to influence sensory memory Longer delays = decreased capacity Sensory Memory Recap What? Example? Capacity? Duration?  Outline Defining memory and the Modal Model Sensory Memory Short-term Memory The Working Memory addition  Short Term Memory (STM) Information filtered from Sensory Memory -> STM Capacity: Domain-specific Auditory = 7+-2 items Visual = 4+-1 item Duration: Order of seconds Important process in STM: Mental rehearsal  Short Term Memory (STM): Rehearsal 693726481 6 693726481 9 693726481 3 … 7 2 6 4 8 Rehearsal = repeat 1 Function: Extends duration of information in STM  Short Term Memory (STM): Duration Brown (1959), Peterson & Peterson (1959) Question: How long does information remain in STM without rehearsal? Methods: Step 1: Participants see short strings of letters (ex: DYG) Step 2: Participants count backwards (ex: 18-17-16-15-…) Step 3: Participants report the string of letters from Step 1 TBE 92-89-86… Recall letters. GQR 50-47-44-41-38… Recall letters.  Short-Term Memory: Duration 1 Accuracy (proportion correct) 0.9 0.8 Describe the 0.7 pattern in the 0.6 0.5 data 0.4 0.3 0.2 Time Accuracy 0.1 0 0 3 6 9 12 15 18 Retention Interval (sec) Brown (1959), Peterson & Peterson (1959)  Short-Term Memory: Duration Information remains in STM for brief period < 18 seconds New question: How do we explain the loss of information over time (ie. Forgetting)? Decay Interference  Short-Term Memory: Forgetting Decay Interference Proactive Retroactive Old info New info interferes with interferes with new info old info  Short-Term Memory: Duration Results Revisited 1 Accuracy (proportion correct) 0.9 Does the data reflect 0.8 decay or 0.7 interference? 0.6 0.5 Authors’ argument: Decay 0.4 0.3 Numbers do not 0.2 interfere with letters 0.1 0 But… 0 3 6 9 12 15 18 Retention Interval (sec)  Other evidence suggests interference… Trial 1 Count Report KQF 33-30-27… KQF Trial 2 Count Report MHZ 102-99-96… MHZ Complete multiple trials, then Question: Is there look at data trial-by-trial interference from trial to trial? Keppler & Underwood (1962)  Other evidence suggests interference… Look at STM retention trial by trial T1 What is the important pattern in T2 the data? T3 Evidence of interference! Time Delay (sec) Keppler & Underwood (1962)  Short Term Memory (STM): Capacity Miller (1959): The magic number 7, +- 2 (auditory) Visual = 4 +- 1 Capacity-resolution tradeoff: More detailed memory = fewer items remembered Some evidence that visual resolution > auditory resolution Big Question: What constitutes an “item” in STM? Features vs objects?  Short Term Memory (STM): Capacity Manipulating multiple features of a single object does not affect how many items remembered Evidence for Objects as items Luck & Vogel (1997)  Short Term Memory (STM): Capacity Not all features of an object are equally remembered Evidence against Object as item Take-home message: Sometimes the item is Bays, Wu, & Husain, 2011 an Object, sometimes the item is a Feature Short Term Memory (STM): Maximising Capacity Real-world: Remember more than single items Chunking: Create a “unit of meaningful information” 7 8 784 4 1 3 135 5 6 8 680 0 Short Term Memory (STM): Recap What? Rehearsal? Duration? Capacity?  Outline Defining memory and the Modal Model Sensory Memory Short-term Memory The Working Memory addition  Update to the Modal Model: Working Memory Short-term memory (STM) conceputalisation = too static Working Memory (WM): More active form of short-term memory WM gets things done (processing) STM keeps things around (storage) Maintenance and manipulation are key to WM  When do we use working memory? “One relies on working memory to retain the partial results while solving an arithmetic problem without paper, to combine the premises in a lengthy rhetorical argument, or to bake a cake without making the unfortunate mistake of adding the same ingredient twice. (Your working memory would have been more heavily taxed while reading the previous sentence if I had saved the phrase “one relies on working memory” until the end of the sentence, which I did in my first draft of that sentence; working memory thus affects good writing.)” (Cowan, 2008, p. 325) Components of Working Memory: Baddeley’s Model CENTRAL EXECUTIVE -central pool of mental resources -control & decision processes (attention) PHONOLOGICAL VISUO-SPATIAL LOOP “SKETCH PAD” -“inner voice” -“inner eye” -verbal rehearsal -visual imagery -capacity = 7 +/- 2 -mental rotation  Working Memory: Central Executive Gatekeeper of information Close relative of attentional control Sorts what is processed in WM Sorts what enters STM storage Working memory capacity influenced by distractors  Attention is involved in the central executive: Condition 1: 2 Items Condition 2: 4 Items Condition 3: 2 Items + (Easy) (Hard) Distractors Attention is involved in the central executive High WM Capacity Participants Low WM Capacity Participants Condition 1 Condition 2 Condition 3 Easy Hard Distractors Working Memory: The Visuospatial Sketchpad Encodes information in visual form Object manipulation  Working Memory: The Phonological Loop Auditory component of working memory Encodes information in acoustic form, even if it could be visual Ex: written words -> acoustic code  The Phonological Loop: Evidence of an Acoustic Code Acoustic confusions: Remember similar, but incorrect, sounds Experiment 1: Present 6 letters (one at a time) in noise Task = report back in order Make acoustic confusions Experiment 2: Present 6 letters (one at a time) visually in noise T Still made acoustic confusions! Conrad (1964)  Recap Basic processes of memory Modal Model of Memory Duration and capacity of different types of memory Explanations for forgetting Working memory How information is encoded in working memory  Learning Objectives Define basic processes of memory Describe the component of the Modal Model of Memory Identify duration and capacity of sensory and short-term memory, including how we study this and what affects duration and capacity Differentiate types of interference that lead to forgetting Describe the Working Memory Model and how it modifies the Modal Model of Memory Explain how information is coded in working memory