Section 2 : Memory - Research on Memory and Types Flashcards
Research on Coding
Baddeley
Coding - process of converting memory between different stores
Method:
4 differnt lists of words
-acoustically similar
-acoustically disimilar
-semantically similar
-semantically disimilar
Participants shown list, asked to recall in order
Recall:
Immediate, STM
20 mins later, LTM
Results:
STM - worse when acoustically similar
LTM - worse when semantically similar
Conclusions:
Info coded acoustically in STM
Info coded semantically in LTM
Research on Coding
Evaluate Baddeley
- lacks ecological validly
- other methods of coding (visual) which this study doesn’t consider
- independent groups design means no control over participant variables
Research on Coding
Evaluate 1
Separate memory stores
Strength
-concluded clear difference between STM and LTM
-as coded differently, qualitative differences
-contribute to Multi-Store model
Research on Coding
Evaluate 2
-Artificial stimuli
-Weakness
-Word lists, unlike every day memory tasks
-No personal meaning
-Does not reflect memory in everyday life
-When meaningful use semantic coding may vary
Research on Capacity
Jacobs
Digit Span
Method:
-Read out a list of digits
-Participants asked to recall in correct order
-Length of list increased if participant correctly recalled last number
Results:
Mean span of:
Digits - 9.3
Letters - 7.3
this capacity increased with age during childhood
Conclusions:
-STM has a capacity of 5-9
- Individual difference were found as STM increases with age, possibly due to memory techniques e.g. chunking
- digits may have been easier to recall as there were only 10 different digits to remember compared to 26 letters
Evaluate Jacobs research on capacity - digit span
Strength
Been replicated
Jacobs - old study, may have lacked control
Eg digit spans may have been underestimated eg due to distractions - cofounding variable
BUT
Same conclusions from Bopp and Verhaeghen
Increases validity for test of digit span in STM
WEAKNESS
artificial research, lacks ecological validity
Research on Capacity
Span of memory and chunking
Miller
Observations of every day practive
eg 7 days of week
Concluded
-Capacity of STM is 7 +-2
-People recall 5 words as easily as 5 letters due to chunking
Evaluate Millers Span of Memory and chunking
Weakness
May have overestimated STM capacity
Cowan - reviewed research, concluded capacity of STM is 4 +-1 chunks
Suggests - Miller overestimated
Research on duration
Duration of STM
Peterson and Peterson
24 students, 8 trials
one trial - consonany syllable to remember and 3 digit number
Count back from number, preventing mental rehersal (rehersal would increase the duration of the STM)
Retention interval - Asked to stop after specific time intervals eg 3, 6, 9 seconds
Results - 2 seconds avg recall 80%, 18 seconds 3%
STM about 18 seconds without rehersal
Evaluate Research of Duration
Peterson - STM
Weakness
Stimulus material was artificial
BUT - sometimes try remember meaningless info eg phone numbers
BUT - does not reflect everyday tasks
Lacks external validity
Research on duration
Duration of LTM
Bahrick
392 American students, 17 to 74
Highschool yearbooks,
1 - photo recognition test, 50 photos
2 - free recall test, all names of graduating class
Photo Results
Tested within 15 years of graduation
-90% accurate recall
48 years
-70% accurate recall
Free recall
After 15 years
-60% accurate
After 48 years
-30% accurate
LTM may last forever
Evaluate
Research on duration - LTM
Bahdrick
Strength
High external validity
Research investigated meaningfull memories eg names (by Shepard)
More realistic results for duration of LTM
Tulving
Stated that the MSM was too simplistic
Stated 3 LTM stores
Episodic
Semantic
Procedural
define coding
information transformed in to a format in which it can be stored and retrieved from meory
What is episodic memory
-mental diary
- Stores information about events that you’ve actually experienced, e.g. concert
- stores facts and knowledge that we have learnt and can consciously recall
- does not contain details of time or place where you learnt the information
What is semantic memory?
-Mental encyclopedia
-eg meaning of words
-memories are not time-stamped
-factual information
-Tulving, less vulnerable to distortion and forgetting compared to episodic memory
What is procedural memory
- stores knowledge of how to do things e.g. walking
- info can be consciously revcalled
- eg playing the piano
Evaluating
Types of LTM
Clinical Evidence
Strength
-Evidence from HM and Clive Wearing
-Episodic memory in both was impaired, brain damage
-semantic + procudural memory remained functional
-supports Tulving, one store can be damaged, others remain functional
BUT
Clinical studies lack control of variables
Researcher had no control of what happened before or during the injury, and no knowledge of their memory prior to the injury
lack of control, limits the validity of conclusions and types of LTM
Evaluating types of LTM
Conflicting Neuroimaging evidence
Weakness
CHECKKKKK
-Conflicting findings linking LTM to areas of the brain
-Buckner and Petersen, semantic left prefrontal cortex and episodic, right
-Tulving, episodic left prefrontal cortex,
Evaluating Types of LTM
Real World Application
Strength
Understanding types of LTM, helps aiding those with memory problems
-Old age, episodic memory still present but harder to recall
-Belleville et al, trained participants to perform better on episodic memory task
-distunguishing between memory types can help develop specific treatments
Evaluating Types of LTM
Same or Different
-Recently, Tulving states that episodic is a subcategory of semantic memory
-possible to have damaged episodic and functioning semantic
-not possible to have functioning episodic and damaged semantic
BUT
-Hodges and Patterson, some people with ALzheimers can have episodic but not semantic
What did sterling investigate
Investigated the sensory register using brief displays
What was the method of Sperling 1960
- Lab experiment
- shown a grid with three rows of four letters for 50 milliseconds (0.05s)
- then they had to immediately recall either the whole grid or a randomly chosen row
What was the results of Sperling 1960
- when recalling the whole grid they only managed to recall 4 or 5 letters on average
- when a recalling a row, participants could recall 3 items average no matter which row
what was the conclusion of sperling 1960
- the participants didn’t know which row was going to be selected , so in theory they would have been able to recall items from any row meaning almost the whole grid was held in their sensory register
- they couldn’t report the whole because the trace faded before they could finish recall
what are the evaluations of Sperling 1960
- lab experiment, variables could be controlled and easily replicated
- lacks ecological validity, people don’t normally have to recall letters in response to a sound so results might not represent what would happen in the real world
what was the method of peterson and peterson
- participants were shown nonsense trigrams (3 random consonants e.g. CVH) and asked to recall them after 3, 6, 9, 12, 15, 18 seconds
- during the pause they were asked to count backwards in threes from a given number
- this interfered with the participants so they wouldn’t repeated the
what were the results of peterson and peterson
- after 3 seconds participants could recall about 80% of trigrams correctly
- after 18 seconds only about 10% were recalled correctly
what was the conclusion of peterson and peterson
when rehearsal is prevented very little can be held in the STM for longer than 18 seconds
what was the evaluations of peterson and peterson
+ lab experiment, variables were tightly controlled
- nonsense trigrams we’re artificial so lacks ecological validity
- meaningful or real life memories may last longer in the STM
- only one type of stimulus was used; the duration of STM may depend on the type of stimulus
- each participant saw many different trigrams, could have led to confusion meaning that the first trigram was the only realistic trial
What was the method of Bahrick et al 1975
- 392 ppts asked to list names of ex classmates (free recall)
- they were shown photos and asked to recall names of the people shown (photo-recognition test)
- or given names and asked to match them to a photo of the classmate (name-recognition test)
What was the results of Bahrick et al
- within 15 years of leaving school, participants could recognise about 90% of faces and names and they were about 60% accurate on free recall
- after 30 years, free recall had declined to about 30% accuracy
- after 48 years name-recognition was about 80% accurate and photo recognition about 40% accurate
What was the conclusion of Bahrick et al 1975
- The study is evidence of Very Long term memories in a real life setting.
- recognition is better than recall, so there may be a huge store of information but not always easy to access all of it; you just need help to get to it
What was the evaluations of Bahrick et al 1975
+ field experiment, high ecological validity
+ showed better recall than other LTM studies
- hard to control all variable in field experiments, makes findings less reliable
- info recalled may be because it was meaningful and therefore stored better
- this type of info could be rehearsed (still in touch with classmates etc.) increases the rate of recall
- results can’t be generalisable to other types of info held in the LTM
What is Miller’s Magic number
Seven plus or minus 2
What did miller suggest to make sequences more meaningful
We use chunking, e.g. if the sequence is 20031987 we chunk it to become 2003 1987 so it becomes more easier to remember
How do we try to keep information in the STM
By actively repeating it to ourselves, generally involving acoustic coding (about how the info sounds)
How do we try to keep information in our long term memory
Generally semantic coding (about the meaning of the information), it’s more useful to code words in terms of their meaning, rather than what they sound or look like however can also be coded thru visual and acoustic
