Lecture 4: Short-Term Memory Flashcards
What do we want to know about memory?
- type of things our memory can hold
- limiting factors of memory
- processes that allow information to enter and exit memory
Describe the Atkinson-Shiffrin multi-store (modal) model of memory.
- structural, serial, modular
- memory stores: sensory, short-term, long-term
- control processes: attention, rehearsal, transfer and retrieval
- basic structure guideline
What is sensory memory?
- limited capacity store (9-12 items) that holds basic sensory information for a very limited amount of time
- different store for each of our senses
- attention helps pass items in sensory store on to short-term memory
What are the limiting factors of short-term memory?
- without rehearsal the duration of STM is only a few seconds (~10-30 s)
- rehearsal keeps information in STM and helps pass it on to long-term memory
What is the “magic number” for short-term memory?
7±2
What did Naveh-Benjamin & Ayres discover about short-term memory?
- when asking participants to remember a series of numbers, mean syllables per digit was inversely proportional the digit span in memory items
- suggests that information in STM is stored acoustically
What evidence is there that information in the short-term memory is stored acoustically?
- Naveh-Benjamin & Ayres study
- STM span is smaller for rhyming lists
How did Luck & Vogel discover the limit of visual short term memory
- projected boxes with an assortment of items
- after a delay subjects were shown another projection and asked if the boxes were the same
- 1-3 items showed near-perfect accuracy, 4+ showed a sharp decline
What did Vogel & Michizawa discover about short-term memory?
- using the Luck & Vogel boxes, they measured ERP from brain
- brain activity plateaued after 4 items
What technique did Sternberg develop to research how items were retrieved from short-term memory?
- participants asked to memorize or ignore a number of letters
- after baseline period they decide whether they recognized a probe item as coming from what they had to memorize
- manipulates number of mental scans but keeps encoding and response constant
What did Sternberg discover from his studies into short-term memory?
Reaction time increased as list length increased
Reaction time for present and absent trials was approximately the same
Overall, data suggests a serial exhaustive search
- May be parallel search but more load burdens the process
Describe the Brown-Peterson task.
- present thing to remember
- count backwards to prevent rehearsal
- recall
What is interference theory?
- theory of forgetting from short-term memory
Retroactive interference (RI): inhibitory effects of new information on old information
Proactive interference (PI): inhibitory effects of old information on new information
What did Wicken’s study show about memory?
- several sets of fruits to memorize
- final set was either fruits, vegetables, or careers
- memory for careers set increased dramatically
- shows effects of proactive interference
What is working memory?
- limited capacity system but (like attention) it is not determined by any one factor
- allows us to both temporarily store and manipulate information
Describe Baddeley’s working memory model.
- consists of 3 auxiliary storage systems under central control
> visuo-spatial sketchpad
> phonological loop
> episodic long-term memory
What is the phonological loop?
- limited storage for acoustic/verbal information
> Phonological store
> Articulatory rehearsal process - articulatory suppression provides evidence for articulatory rehearsal process
> impairs mental arithmetic and reading comprehension
What is the visuo-spatial sketchpad?
- separate, limited short-term memory storage component for visual/spatial information
> processing in visuospatial sketchpad mirrors processing of real items
What is the episodic buffer?
- used to integrate information from different modalities into a complete memory
> binds information from WM components and LTM - limited capacity
- controlled by central executive
What is the central executive?
- control centre for working memory
- considered attentional control mechanism
- required for initiating retrieval, planning actions and integrating information
- does not have any storage capacity itself, but has attentional resources that can be shared among components
What did Vogel et al. discover about the central executive in working memory?
- people with high working memory capacity are better able to inhibit irrelevant information
In experiment:
- high capacity processed two items and two items with distractors with the same amount of brain activity
- low capacity processed two items with distractors and four items with the same amount of brain activity
Compare and contrast dual task method and operation span.
DUAL TASK METHOD
- based on the idea that WM resources are attentional resources
- more cognitive load = more attentional resources used
- researchers are interested in what happens to performance as WM resources become unavailable
OPERATION SPAN
- task requires storage and processing at the same time
(do the math problem + remember the words)
- span tasks correlate with many everyday tasks, including academic performance
- researchers are interested in individual differences in task performance
How do we chunk information in memory?
- put into meaningful units based on information in long-term memory
Why is short-term memory span smaller for rhyming lists?
- phonological similarity effect
- proves that some information is stored verbally/acoustically
What did Posner discover about attention?
- attentional shift to a target area occurs prior to any eye movement
- spatial attention is not completely reliant on conscious visual input
What is the articulatory rehearsal process?
- converts sensory information into verbal codes
What is articulatory suppression?
- any kinds of sounds made when trying to rehearse an item (saying “lalalalala” during delay)
- uses up rehearsal coding
- impairs math and reading comprehension
Give one example of retroactive and proactive interference.
If a student who is fluent in French starts learning Italian…
RETROACTIVE:
- they have trouble going back to French and only recall the Italian words
PROACTIVE:
- they have trouble learning Italian because the French is similar enough to throw them off
What is recoding?
- process of grouping items together, then remembering the newly formed groups
What is release from PI?
- release from proactive interference
- when decline in performance caused by proactive interference is reversed because of a switch in the to-be-remembered stimuli
- i.e. Wickens memory study fruits vs. vegetables vs. flowers vs. jobs
What is a serial position curve?
- graph of item-by-item accuracy on a recall task
- serial position refers to original position an item had in a study list
What is a serial exhaustive search?
- way in which information is retrieved from short-term memory according to Sternberg
- memory set is scanned one item at a time (serial)
- entire set is scanned on every trial, whether or not a match is found (exhaustive)
What is the phonological store?
- passive store component of phonological loop
- holds on to verbal information
What is the articulatory loop?
- component of the phonological loop involved in the active refreshing of information in the phonological store
What is boundary extension?
- when people tend to misremember more of a scene than was actually viewed, as of the boundaries of an image were extended further out
- shows visuo-spatial sketchpad adding previous knowledge to a memory
What is representational momentum?
- phenomenon of misremembering the movement of an object further along its path of travel than where it actually was when it was last seen
