5. SHORT TERM AND WORKING MEMORY Flashcards
Define memory.
- processes involved in retaining, retrieving, and using information about stimuli
- or events, ideas, skills after original information is no longer present
- is active at any time
- past experiences have an impact on how you think
What is the Modal model of memory?
- consists of sensory, short term and long term memory
- sensory memory: initial stage that holds all incoming info for secs/ fracs of a sec
- short term memory: holds 5-7 items for 15-20 secs
- long term memory: hold a large amt of info for years, or decades
What is sensory memory?
- when smth is presented briefly
- eg. face illuminated by a flash
- your perception continues for a frac of second in the dark
- this brief persistence of image is called sensory memory
- this BP is the continued perception of a visual stimulus even after it is no longer present
OR
- the retention of memory for brief periods of time of the effects of sensory stimulation
What is an eg. related to Sensory Memory?
Sperling’s experiment- measuring the capacity and duration of the sensory store
Part A.
- flashed array of letters on the screen for 50 ms
- asked partis to report as many letters as possible (WHOLE REPORT)
- RESULTS: out of the whole 12 letters, they only reported avg 4.5/12 letters (37.5%)
- apparently they saw all letters but their perception faded rapidly
Part B.
- parti saw 12 letter for 50 ms
- but immediately aft it was flashed, they heard tones to report which row (PARTIAL REPORT)
- high tone = top row
- medium tone = middle row
- low tone = bottom row
- as the tones were presented imme aft the letters were turned off, their attention was direct not to the actual letters which were no longer present, but whatever trace remained in their minds aft the letters were turned off
- RESULTS: 3.3/4 letters = 9.9 items (82%)
- this occurred despite which row
- he concluded they saw all the letters but they faded as well
Part C.
- he did a DELAYED PARTIAL REPORT to find the time course of fading
- letters were flashed on and off
- then the tone cue, after a short delay (1 sec)
- RESULTS: partis only able to report slightly more than 1 letter in a row
HE CONCLUDED that a short lived sensory memory registers all of the info that hits our visual receptor, but this info decays within less than a sec.
- this can be called iconic memory/ visual icon
What are the separate sensory memory stores?
- echoic buffer
- for auditory info - iconic buffer
- for visual info - haptic buffer
- for sensory info
- sensory stores are modality specific
- they also have large capacity
- there is fast degeneration due to stimulus onset
- info can be lost thru masking (putting in new info that covers prev info that was put bef)
- limited amt of info can be transferred to other memory stores for further processing
What is Iconic Memory?
- persistence of sound which lasts for a few seconds after presentation of the orig stimulus
- eg. when you hear someone and don’t understand and say ‘what’
- but bef the person can repeat, you can ‘hear’ it in your mind
What is short term memory?
- info that stays in our memory for brief periods
- about 10-15 seconds if we dont repeat it over and over
- smaller capacity than perceptual stores (5-8 items)
- includes both new info received from sensory stores and info recalled from LTM
- slower rate of decay than perceptual stores
- rehearsal can prevent memory degradation (conscious control)
- attention is usually required to place info in STM
What is an eg. related to STM?
Brown Peterson Task- measuring the duration of STM
- partis asked to read 3 letters, then numbers
- eg. FZL345
- then they are tasked to count backwards by threes (345, 342…)
- aft a set time they are asked to recall the 3 letters
- RESULTS: aft 3 secs of counting, partis performed at 80%
- after 18 secs of counting, partis performed at 10%
- the reduction in performance is explained by the existence of decay
- this is the vanishing of a memory trace due to the passage of time + exposure to competing stimuli
HOWEVER, analysis shows that there is little decrease in perf if only the first trial is included. This could be due to proactive interference
Proactive interference:
- when info learned previously and stored in LTM interferes w learning new info
- here the prob is that the first itme you were asked to learn FZL, but now AED
- eg. your native language may make it more difficult to learn and remember a new foreign language
Retroactive interference:
- occurs when new learning interferes w remembering old learning
- eg. aft u get a new tele no. and use it for awhile, u might have diff remembering old phone no.
HENCE is STM around 3 secs, or 15-20 secs? when non letter stimuli (no.s) are used in the first trial, proactive interference vanishes and info can be held for 15-20s in STM. apparently using nos. doesnt have the effect of carrying over to next trial
What are some ways to hold memory in STM?
- Rehearsal: repeating a stimulus over and over
- Chunking: small unit words can be combined into larger, more meaningful units like phrases or sentences
- chunks are collection of elements that are strongly assoc with one another but weakly assoc with elements in other chunks
- chunking in terms of meaning increases our ability to hold info in STM - Strategies to make a stimulus more memorable
- Strategies of attention to help you focus on info that is important or interesting
What is Digit Span?
- the no. of digits a person can remember in STM
- results are 4-9 items
- eg. cantonese (9.9) is faster than english (6.6) which is faster than welsh (5.8)
- digit span is greater in languages with 1) smaller avg no. of syllables per digit, 2) shorter avg syllable duration per digit
What is Change detection?
CD:
- another procedure to measure the capacity of STM
- 2 pics of a scene are flashed one aft another
- partis task is to determine what had changed betw the first and second pic
- the conclusions from these experiments was that people often miss changes in a scene
What are some limitations of the Modal Model of memory?
- It is oversimplified as it claims that STM is modality free
- It also controls or manipulates the processes of data, and is not clearly specified
- Claims rehearsal is necessary for transfer to LTM
- it also de-emphasizes the roles of proactive interference and the retrieval of cues in STM and forgetting
Define Working Memory and its related components.
WM:
- a limited capacity system for temp storage
- and manipulation of info for complex tasks
- eg. comprehension, learning and reasoning
- Central Executive
- Phonological Loop
- Visuo Spatial Sketchpad
- Episodic Buffer (not in Baddeley’s model but it was found later on in research)
Baddeley and Hitch’s model (1974) mainly contains 2 modalities (phonological loop and visuo spatial sketchpad). On the other hand, the CE is for manipulating items in memory and coordinating verbal and visual info
How is STM different from WM?
STM holds info for a brief period of time while WM is concerned with processing and manipulation of information that occurs during complex cognition
Explain the Phonological Loop.
Here, PL stores things verbally and phonologically and not based on semantic information. It can be shown through the Phonological Similarity Effect and the Word Length Effect.
Phonological Similarity Effect:
- the confusion of letters of words that sound similar
- Conrad (1964) flashed target letters
- instructed partis to write down letters in order of presentation
- found that when they made errors, they were most likely to misidentify the target letter as another letter that sounded like the target
- eg. F was most misidentified as S or X but not E
Word Length Effect:
- occurs when memory for lists of words is better for short words than for long words
