Week 8 - Sensory and Short-term memory/working memory

What is memory

The process where we use information from the past to generate/support cognitive functions in the present

• active function

3 basic mechanisms of memory

1. Encoding

2. Storage

3. Retrieval

1. Encoding

The translation of information into a neural code that can be understood/represented in the brain

• early on in the process

• ex. moving into a new house - sorting specifics into a box

• needs to turn information and create a neural code that your brain can interpret. One of the first steps to have a functional memory

2. Storage

Retention of the encoded information

• varied length in time (depends on how much information)

• need to retain the information that was stored, not a fixed length of time

• ex. the box is in storage for varying times depending when you move

3. Retrieval

Recovering/finding the encoded, stored information for use in behavior/cognition

• ex. taking the stuff out of the box out of storage

Modal Model of Memory

• 3 components

  1. Sensory memory

  2. short-term memory

  3. Long-term memory

MMM: Information processing approach

• Brain actively manipulates information and process it (need to be able to manipulate)

• Humans are not passive receivers of information

some information gets transferred to long term

Sensory Memory Capacity

“sensory echo” or “sensory face”

Capacity = High, not all of it goes into short term memory

• attention is a filter - it filters out irrelevant information. Similar process from sensory to short-term memory. Only some of the sensory memory will be transferred

Sensory Memory Duration

• Very brief (order of milliseconds)

Example of Sensory Memory

• Persistence of Vision

• Phenomenon - if you light a sparkler a trace it through the air it seems to form full shapes, this echo happens because your sensory memory

demonstrating persistence of vision: if you flip the card fast enough both images are being held in sensory memory which causes it to look like you are looking at one image

Iconic Memory

• visual signals persist

Echoic memory

• Auditory signals persist

• someone’s talking to you and you stop listening and then they call you back to the conversation and you can only recall what they just said but nothing more of the conversation

Testing Capacity of Iconic Memory (Sperling 1960): methods

How much info do we glean from a single glance?

• on average people report 4-5 letters (out of 12)

• Claimed to see the whole array but forgot while reporting

• Claimed the array seemed to fade but was able to mentally examine the screen for a brief period of time

Testing Capacity of Iconic Memory: Follow-up

• Partial Report Procedure: Participants report a specific row of letters in the array

• Crucial Manipulation: A cue (tone) is played to participants after they see the screen. The cue indicates which row to report

instead of asking what you saw, tell me about a specific row of letters. People aren’t told which row they have to report until they have seen. This causes individuals to hold the mental image in their head

Iconic Testing Memory: Results

• Partial report ~ 80% (see report and can say which letter)

• Whole report ~ 25-30% (what participants data tends to show only up to 6 letters can be remembered)

• Optimal = 100%

results tell us peoples sensory memory is much larger than 4 or 5 letters. it is much bigger.

We can hold quite a bit of information in sensory memory, BUT we MUST apply ATTENTION to select it out and use it. (attention combining with memory, have to use attentional capacity to make it available for use).

Duration of Sensory Memory

• 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

Duration of sensory memory: Take Away

• Duration is short, capacity can be high BUT duration and capacity interact to influence sensory memory

• longer delays = decreased capacity

the graph: how long it takes the cue to show up. Longer time distance between when the image was shown and then asked which column to remember

Sensory Memory Recap

What? Trace or echo of what you saw or heard (other senses)

Example? Persistence of vision - we can see the visual trace. Moving lights around fast enough you can see the whole picture

Capacity? High - 10 items?

Duration? Milliseconds - maybe a couple seconds, depends on modality (auditory can last longer than visual)

Short term memory Capacity

• Information filtered from Sensory Memory to Short term memory (STM) - not everything goes from sensory to STM

• Capacity = Domain-specific

  • auditory = 7±2 items

  • visual = 4± 1 item

STM Duration

Order of seconds

very short, (30 seconds, maybe 1 minute)

Information process in STM

mental rehearsal

• rehearsal = repeat

• FUNCTION = extends duration of information in STM

STM: Duration - Example

Brown (1959), Peterson & Peterson (1959)

How long does information remain in STM without rehearsal?

STM example: methods

• step 1: participants see short strings of letters (ex. DYG)

• step 2: participants count backwards (ex. 18, 17, 16, etc. )

• step 3: participants report the string of letters from step one

STM example: results

• The pattern of data represented an increase in time and decrease in accuracy (when the gap gets bigger, peoples accuracy decreases)

• information remains in STM for brief period - <18 seconds

STM: Forgetting

• How do we explain the LOSS of information over time (forgetting)

  • decay vs. interference

Decay

leaking bucket - trying to hold water in your hands (information slowly fades out of short term memory

Interference

• More of an active process - gets in the way of short term memory

Proactive Interference

old info interferes with new info

• learning choreographed dance - now changing the steps and you have a hard time learning the new steps

Retroactive interference

new info interferes with old info

• second information taken in replaces the old

STM interference results

• Numbers do not interfere with letters

• BUT there is evidence of interference between trials

STM : Capacity Example (miller 1959)

• What constitutes an “item” in STM? features vs. objects?

Capacity-resolution trade-off: more detailed memory = fewer items remembered (some evidence that visual resolution > auditory information)

• Manipulating multiple features of a signal object does not affect how many items are remembered

• Not all features of an object are equally remembered

** Sometimes the item is an object, sometimes the item is a feature

• consequence of remembering things at feature level - you will remember less objects because more features make up on object

STM: Maximizing capacity

• Remember more than single items

• Chunking: create a “unit of meaningful information”

• much easier to remember 3 numbers

Short term memory recap

What? Memory from the past couple minutes/seconds

Rehearsal? Repeating information either internally or outload - means to increase capacity and duration of STM

Duration? Few minutes/seconds

Capacity? 7± 2 (auditory), 4 ± 1 (visual)

Update to the modal model: Working memory

Working memory: more active form of short-term memory

• WM gets things done (processing)

• STM keeps things around (storage)

• Maintenance and manipulation are key to WM

Baddeley’s model of components of working memory

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)

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

• the more the items the harder the task

attention involved in the central executive

WM: The visuospatial Sketchpad

• encodes information in visual form

• object manipulation

WM: 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

Acoustic confusions made in both cases!!