PSY 260 Short Term Memory Ch 5

Modal Model of Memory - Atkinson & Shiffrin, 1968

Flow diagram, called the modal model because it included many of the features of memory models that were being proposed in the 1960s

An example of proactive interference in long-term memory

Old phone number interfering with remembering new phone number

Evidence support Persistence of Vision

Prior to 1960, many scientists noted that visual information seems to persist for a few hundred milliseconds after the offset of a stimulus This was based on introspection, with no data Example: Sparklers, camera flashEvidence support Persistence of Vision

Sperling 1960 whole report task

Question: Why couldn't Sperling conclude that only 4.5 items can be recognized from a brief display? Answer: Subjects may have recognized all of the letters, but in the few seconds needed to report them the letters may have faded from sensory memory.

What did Sperling's experiment on sensory memory show us?

Sensory memory is important for • collecting information to be processed • holding information briefly while initial processing is going on • filling in the blanks when stimulation is intermittent

Sperling's Experiment Conclusions

Sperling concluded that sensory memory registers all or most of what we take in, but it decays very rapidly (less than a second for visual information)

Phenomena Explained by Working Memory: Phonological Similarity Effect

The confusion of letters or words that sound similar

Phonological Loop & Visuospatial Sketchpad

The phonological loop and visuospatial sketchpad are relatively independent of one another but they are connected through the central executive.

Iconic Memory

Visual sensory memory: A visual sensory memory system that can hold a lot of unprocessed visual information for about ½ second.

Sperling's Experiment: Whole Report Method

flash up 12 letters for 50 msec, then ask a person to report back as many as they can. □ Subjects could only report back about 4.5 of the 12 letters.

short term memory

sensory information flooding into the eyes-->attention and recognition passes desired number into short-term memory (STM)-->a rehearsal "control process" is used to maintain the information in STM-->Encoding processes are used to move the information into long-term memory (LTM)-->Information can be copied from LTM back into STM and used at a later time.

the modal memory model - Shiffrin, 1968

sensory memory - initial stage holding raw information for a very short time; a couple secs for sounds, split sec for vision. -Short-term Memory (STM) - intermediate stage holding 4-7 things for 15-30 secs. Mediates ongoing tasks and holds current thoughts (the "seat of consciousness"). -Long-term Memory (LTM)- holds unlimited information for an unlimited time.

visual persistence

the retention of sensory information for a very brief time for vision

sensory memory

the retention of sensory information for a very brief time. for vision this is called visual persistence

Sperlings Conclusions

• A short-lived sensory memory registers all or most of the information that that hits our visual receptors, but this information decays within less than a second • Iconic memory/the visual icon - brief sensory memory for visual stimuli • Auditory stimuli has shown that sound also persists in the mind • Echoic memory - persistence of sound in the mind; lasts for a few seconds after presentation of original stimulus

Modal Model of Memory: Three Major Structural Features (Stages)

1.) Sensory Memory: an initial stage that holds all incoming information for seconds or fractions of a second 2.) Short-Term Memory (STM): holds 5-7 items for about 15-30 seconds 3.) Long-Term Memory (LTM): can hold a large amount of information for years or even decades

Sperling's Experiment: Delayed Partial Report Method

12 letters are again flashed for 50 msec, but now subjects report back only a cued row. - See display & hear a tone immediately after, but is delayed by 0-1 sec

Memory System Includes Control Processes

Active processes that can be controlled by the person & may differ from one task to another

Echoic Memory

Auditory sensory memory: An auditory sensory memory system that can hold sound information for about 2 seconds.

How do we know what the duration of STM is? "Brown & the Petersons"

Brown & the Petersons →Concluded that the duration of STM is less than 20 sec. →They believed that performance dropped due to the decay of memory in STM. •Some suggest that the drop-off in memory in the B-P task not due to decay but due to proactive interference

Retroactive Interference (RI)

Confusing more recently remember learned material with what you are trying to remember. □ When newer information in memory interferes with the recall of older information.

Proactive Interference

Confusing previously learned material with what you are trying to remember. □ When old information in memory interferes with the recall of newer information.

Sperling Experiment: What did the partial report show us that the whole report didn't?

In the partial report average participants saw 82% of letters no matter which row was cued, it was concluded that the correct description of what was happening was that immediately after the display was presented, participants saw an average of 82% letters in the whole display, but were not able to report all of these letters b/c they rapidly faded as the initial letters were being reported

Information Processing Model

Memory-processes involved in the encoding, retaining,retrieval, and use of information about images, events,ideas, and skills after the original information is gone -Duration: how long information can be held. -Capacity: how much information can be held. -Control Processes: system specific processes affecting duration and capacity.

Sensory Memory

The retention, for brief periods of time, of the effects of sensory stimulation

STM According to the Modal Model

You shouldn't be able to remember the numbers and read the passage at the same time, because it would exceed the capacity of STM.

What is sensory memory's capacity and duration? How do we know that?

• Capacity of sensory memory (large) • Duration " " (brief) • Can register huge amounts of information, but it retains this information for only seconds or fractions of a second

Why do we forget from STM?

• Decay Theory: Information in STM fades away over time; the memory trace gets weaker until it is gone. • Interference Theory: Other perceptual and cognitive events during the retention interval interferes with what you are trying to remember. • Either theory can explain the Petersons' results. Both time and interference was changing over the retention interval.

How does the modal model work? EXAMPLE

• Girl looks up number for pizza place on internet 1.) looking up phone number (all info on screen enters sensory memory) 2.) looking up phone number (focuses on 555-5100; it enters STM) 3.) calling pizza shop (rehearse the number to keep in STM while making the phone call) 4.) memorizing the number (store number in LTM) 5.) few days later, retrieves number to order pizza again (retrieve number from LTM; It goes back to STM & is remembered)

Methods and results of Sperling's experiment

• How much information people can take in from briefly presented stimuli? 3 parts: 1.) Whole Report Method - person saw all 12 letters at once for 50 ms & reported as many as they could remember 2.) Partial Report - person saw all 12 letters, as before, but immediately after they were turned off, a tone indicated which row the person was to report 3.) Delayed Partial Report - same as partial report, but with delay between extinguishing the letters & presentation of the tone Results: 1.) able to report an average of 4.5/12 letters 2.) 3.3/4 letters 3.) only slightly more than 1 letter a row (4 lets for the whole)

Sperlings Graph

• Indicates that immediately after a stimulus is presented, all of most of the stimulus is available for perception (sensory memory) • Over the next second, sensory memory fades, until by 1 second, the number of letters is about the same as the number of letters that were reported using the whole report method • Decrease in performance is due to the rapid decay of iconic memory (sensory memory in the modal model)

Function of Sensory Memory

• It probably helps recognition by freezing information in time, thereby giving recognition a chance to attach meaning to patterns. • Because visual recognition is fast, it doesn't need this information for very long, which explains why visual sensory memory is so short.

Examples of Control Processes

• Rehearsal: repeating a stimulus over and over • Strategies you might use to help make a stimulus more memorable (relating phone number to important history date) • Strategies of attention that help you focus on information that is particularly important or interesting

Forgetting from STM

• The rapid loss of information from memory in the absence of rehearsal. • By rehearsing information (a memory strategy or "control process"), you can retain it indefinitely. • Evidence points to interference (proactive or retroactive) as being the reason why we forget things from STM. □ Information in STM doesn't just fade away over time. □ Time doesn't cause you to forget things, it's the stuff that happens during that time that interferes with your memory.

Persistence of Vision

• The retention of the perception of light in your mind • Example: with sparklers, the lighted trail after waving a lit sparkler is a creation of your mind, which retain a perception of the sparkler's light for a fraction of a second

Braddeley's Working Memory Model

•Alan Baddeley (1974) proposed a new model of STM called working memory.

Chunking

•Combining smaller units into larger meaningful units →So perhaps it's best to say that the capacity of STM is 5 to 9 chunks of information.

Central Executive

•Coordinates information in the phonological loop and visuospatial sketchpad and pulls in information from long-term memory. •Called the attention controller → it determines how attention is focused on a specific task, how it is divided between two tasks, and how it is switched between tasks. •Suggests that this part of working memory and attention are essentially the same mechanism. •Same areas of the brain are activated by working memory tasks and attention tasks.

Central Executive duties in Phonological Loop & Visuospatial Sketchpad

•Coordinates the activity of the phonological loop and visuospatial sketchpad. →It directs attention and decides how to focus, switch, or divide attention.

What is the capacity of STM?

•Find out using a digit span test →Typical capacity is 5-9 items

Phonological Loop

•Holds verbal information for a few seconds →It uses auditory coding (inner voice) to hold information in memory →It also uses an articulatory rehearsal process, which allows information to remain in the store through rehearsal.

Visuospatial Sketchpad

•Holds visual and spatial information for a short period of time →Also thought to be involved in the creation of mental visual images in the absence of a physical visual stimulus.

Working Memory

•STM in the modal model consists of a single component, whereas working memory consists of a number of components. •Working memory emphasizes the processing that takes place in STM over its storage capacity.

Short-Term Memory

•STM is the memory system that holds small amounts of information for a brief period of time •STM's duration is about 15-20 seconds - w/o rehearsal •Rehearsal is repeating a stimulus over and over to keep it in STM

Sperling's Experiment: Partial Report Method

•See display & hear a tone immediately after seeing the display •With the partial report method, participants could report about 3 to 4 letters per row or about 82% of the items.

Properties of Visual Sensory Memory

□ Visual sensory memory has a very high capacity -it can hold a lot of information. □ But has a very short duration, only about ½ second.