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March 22 More about conscious perception Overview of Memory March 24 Sensory Memory March 29 Short-Term/Working Memory (Brooks expt. 1) March 31 Long-Term Memory April 5 NO CLASS April 7 Long-Term Memory and False Memories (Loftus) April 12 Consciousness and Perception without Awareness Subliminal Messages (Vokey and Read) April 14 Memes (Dawkins) Upcoming

Overview of Memory Atkinson-Shiffrin Model Sensory Signals Sensory Memory Short-Term Memory Long-Term Memory ATTENTION REHEARSAL RETRIEVAL

Types of Memory Sensory Memory –brief ( < 1 second) –preattentive / parallel processing (very large capacity)

Sensory Memory

Capacity Describe a simple experiment that could measure the capacity of memory

Capacity Describe a simple experiment that could measure the capacity of memory Briefly present some letters or digits and then ask the subject to report them –Called whole report

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F S F E G S A U T O C G +

Capacity Recall as many letters as you can

Capacity George Sperling - Systematic investigation of memory capacity –Result: subjects accurately recall 3 or 4 items –What can you conclude from this result? –Maybe subjects can only hold 3 or 4 items?

Capacity Could it be that subjects had encoded all the letters but failed to retrieve the information?

Capacity For example: What if they forgot the information before they could report it? –You would get the same result! How could you modify the experiment to measure the instantaneous capacity, before any forgetting can occur?

Capacity Partial Report - briefly present letters or digits and ask subject to report only some of them Report the letters in the row indicated by the arrow

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U E S B O D W A I B V S +

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Which Letters?

Capacity Partial Report Result: subjects can recall any 3 or 4 letters that are indicated by the arrow !

Capacity Partial Report Result: subjects can recall any 3 or 4 letters that are indicated by the arrow ! What does this mean about the capacity of memory?

Capacity There is some part of the perception system that stores huge amounts of information… –in fact, if only a single letter is probed, instantaneous capacity is seen to be unlimited

Duration There is some part of the perception system that stores huge amounts of information… But for how long? How would you design an experiment to measure the duration of this high-capacity memory system?

Duration There is some part of the perception system that stores huge amounts of information… But for how long? How would you design an experiment to measure the duration of this high-capacity memory system? Vary the onset of the probe

Duration Partial Report Probe Delay # of letters potentially recalled 500 ms0 msnever

Duration Partial Report Delay # of letters potentially recalled Interpretation: 1.Information dwells in a brief storage buffer 2.duration of storage lasts about 1/2 of one second 500 ms0 msnever

Iconic Memory a brief storage of raw data in the visual system

Echoic Memory Auditory information is stored in a similar sensory buffer –Echoic memory seems to last for several seconds

Properties of Sensory Memory 1.Brief (iconic ~500ms; echoic ~2 seconds)

Properties of Sensory Memory 1.Brief (iconic ~500ms; echoic ~2 seconds) 2.Virtually unlimited capacity

Properties of Sensory Memory 1.Brief (iconic ~500ms; echoic ~2 seconds) 2.Virtually unlimited capacity 3.pre-attentive

Overview of Memory Atkinson-Shiffrin Model Sensory Signals Sensory Memory Short-Term Memory Long-Term Memory ATTENTION REHEARSAL RETRIEVAL

Short-Term Memory process by which we hold information in mind

Short-Term Memory process by which we hold information in mind example: temporarily remembering a phone number

Characteristics of STM Duration? Capacity? How could one measure these parameters?

Characteristics of STM Limited Duration –Brown-Petersen Task: subject is given a trigram (e.g. C-F-W) to remember vocal rehearsal is prevented by counting backwards recall accuracy tested as a function of retention interval

Characteristics of STM STM decays over seconds

Characteristics of STM Limited Duration –Brown-Petersen Task Interpretation: rapid loss of information in STM (over a period of seconds…much longer than sensory memory)

Characteristics of STM Limited Capacity –How might you measure capacity?

Characteristics of STM Limited Capacity –George Miller –Subject is given longer and longer lists of to- be-remembered items (words, characters, digits)

Characteristics of STM Limited Capacity –George Miller –Subject is given longer and longer lists of to- be-remembered items (words, characters, digits) –Result: Subjects are successful up to about 7 items

Characteristics of STM Limited Capacity –What confound must be considered ?!

Characteristics of STM Limited Capacity –What confound must be considered ?! –Recalling takes time !

Characteristics of STM Limited Capacity –What confound must be considered ?! –Recalling takes time ! –It seems that the capacity of STM (at least measured in this way) depends on the rate of speech - faster speech leads to apparently larger capacity –Some believe capacity is seconds worth of speech

Forgetting from STM Why do we forget from STM? –Does the memory trace decay? not likely because with very small lists (like 1 item) retention is high for long intervals

Forgetting from STM Why do we forget from STM? –Does the memory trace decay? not likely because with very small lists (like 1 item) retention is high for long intervals –Instead, it seems that information piles up and begins to interfere

Forgetting from STM Interference in STM is complex and specific

Forgetting from STM Interference in STM is complex and specific For example, severity of interference depends on meaning

Forgetting from STM Interference in STM is complex and specific For example, severity of interference depends on meaning –Subjects are given successive recall tasks with list items from the same category (e.g. fruits) –final list is of either same or different category - how is good is recall on this list?

Forgetting from STM Accuracy rebounds if category changes

Coding in STM How is information coded in STM?

Coding in STM Clues about coding in STM: –# of items stored in STM depends on rate of speech

Coding in STM Clues about coding in STM: –# of items stored in STM depends on rate of speech –phonological similarity effect: similar sounding words are harder to store/recall than different sounding words

Coding in STM Clues about coding in STM: –# of items stored in STM depends on rate of speech –phonological similarity effect: similar sounding words are harder to store/recall than different sounding words What does this suggest about the nature of information in STM?

Coding in STM It seems that information can be stored in a linguistic or phonological form

Coding in STM It seems that information can be stored in a linguistic or phonological form Must it be stored this way?

Coding in STM It is also possible to keep in mind non- verbal information, such as a map Are there two different STM systems? Read Intro and Expt. 1 in article Brooks