memory lessons 1-4 Flashcards
what are the three categories of STM and LTM
duration
capacity
coding
short term memory duration experiment
peterson and peterson gave 24 undergrad pps consonant trigrams and asked to count backwards in threes to stop rehearsal after intervals of three seconds starting from 3 pps had to repeat trigram.
results: remember 90% of trigrams after 3s 20% after 9s and less than 10% after 18s. MAX STM duration is abt 18s
peterson and Peterson experiment evaluation
strengths: lab experiment so variables are controlled. has high replicability
weaknesses: has low ecological validity as remembering trigrams doesn’t apply to real life. don’t know whether the results are due to forgetting or interference.
long term memory duration experiment
Bahrick et al tested 400 american pps aged between 17-74 yrs to see if they could remember their former classmates.
after 48yrs when asked to link names to faces accuracy was 70%. when asked to recall wo images accuracy was 30%
ltm last a lifetime and recall is higher with cues
bahrick evaluation
strengths: high external validity as they use meaningful material and higher ecological validity
weaknesses: natural experiment so less control of variables such as people keeping in touch which may make results invalid
capacity of stm experiment
jacobs read out 4 digits to pps and asked to recall and added digits to string until unable to recall.
results: on average 9 digits and 7 letters were correctly recalled. capacity increases with age
evaluation of jacobs experiment
strengths: study has been repeated and results found same
weaknesses: lacks ecological validity and temporal validity
miller review of experiments
he found stm capacity is 7+-2 items and can be increased using chunking
3 ways of coding
acoustically - sound
semantically - meaning
visual - looks
baddeley experiment
pps shown sequence of 5 words from four conditions and had to immediately write in order:
acoustically similar, acoustically dissimilar, semantically similar, semantically dissimilar.
when tested immediately pps were least accuratewith acoustically similar words
when tested after 20 mins pps were least accurate with semantically similar words
information is encoded acoustically in stm and semantically in ltm
evaluation of baddeley experiment
strengths: does identify clear difference in the coding of the two memory stores
weaknesses: low ecological validity and doesn’t tell us abt coding memories in everyday life
what are the three stores of memory
STM
LTM
sensory register
multistore model
attention rehearsal
environmental input ———> sensory register ——> STM ——>LTM
l l < ——
l l retrieval
recall l rehearsal
— l loop
what is the duration of the sensory register
250 milliseconds
what are the 5 sensory register stores
iconic store: visual
echoic store: auditory
haptic store: touch
gustatory store: taste
olfactory store: smell
evidence for sensory register
study by sperling where pps were shown three rows of four letters for 0.05s and had to recall either the whole grid or an indicated row or column.
when asked to recall grid pps could recall 4 to 5 out of 12
when asked to recall a row pps could recall on average 3 to 4 items
this shows the capacity is very large while the duration is small
evaluation of sperlings study
highly scientific so the variables are very controlled. low ecological validity
what are the stores capacity duration and coding
SR — unlimited — 0.25s — modality specific
STM — 5-9 items — 30s — acoustic
LTM — unlimited — lifetime — semantic
evaluation of MSM
ADV: remembering the first and last few items in a list because the first few are rehearsed and stored in the LTM and the last few are still in the STM (primary and recency effect)
H.M was a patient study who had brain damage as a result from an operation to remove hippocampus. his personality and intellect remains intact but he is unable to form new LTM so memories are separately stored
DIS: It doesn’t explain lightbulb memories, highly emotional or traumatic memories which are stored in LTM wo rehearsal. A patient K.F got brain dmg from accident and was left w severely damaged STM for verbal info only which proves it is not a unitary store
what are the types of LTM
episodic memory: events or groups of events. prefrontal cortex. hippocampus
semantic memory: knowledge about things. frontal and temporal lobes. hippocampus
procedural memory: skills and abilities to do things. neocortex
differences between types of LTM
episodic and semantic are conscious but procedural are unconscious
episodic and semantic are stored in hippocampus but procedural are stored in cerebellum and motor cortex
evaluation of types of LTM
strengths: case studies of H.M and clive wearing - both had impaired episodic memories but could learn new skills so procedural were intact. this proves that LTM has different stores and are stored in different parts of the brain. pet scans found when a task required semantic memory there was more brain activation in the frontal and temporal lobe comparative to when the task required episodic memory the prefrontal cortex was activated.
weaknesses: gender differences in LTMs so research can’t be generalised to all the population. herlitz analysed LTM abilities in 1000 swedish pps and found females performed better when required episodic memories
what did baddeley and hitch argue
that the STM is not a unitary store unlike the MSM does
what is the working memory model
attention
input ——> sensory register ——> working memory <——> LTM
what is the central executive
has overall control and directs attention to important tasks. controls the three slave systems
what is the phonological loop
converts written words into an articulatory code. has the arculatory process which allows maintenance rehearsal
what is the visio spatial sketch pad
stores and processes visual and spatial info.
The VSS is divided into
visual cache: stores visual data
inner scribe: stores spatial information like remembering the arrangement of objects
what is the episodic buffer
recognised as the WMM doesn’t allow for communication between slave systems. backup store which communicates with LTM and integrates visual and spatial info
coding and capacity of each store
central executive phonological loop VSS episodic buffer
capacity limited. two secs 3-4 objects. 4 chunks
coding. modality free. acoustic. visual. visual, spatial & verbal
baddeley and Hitch experiment
pps were asked to perform two tasks at the same time. a digital span task to repeat numbers and verbal reasoning task to answer true and false qs
The verbal reasoning task makes use of central executive and digital span task uses phonological loop. Participants could do both tasks simultaneously very well, supporting the idea of separate components in STM.
evaluation of WMM
ADV: Accounts for dual tasking because we can use phonological loop and VSS for verbal and visual task as supported by baddeley and hitch experiment. Dispositio used fmri scans to test different components and found prefrontal cortex was activated when verbal and spatial tasks were performed together but not when performed separately suggesting it is involved in the central executive.
DIS: Exact role of central executive is unclear and contains sub parts. Eslinger studied EVR who had cerebral tumor removed and performed well on tests suggesting his central executive was intact but had poor decision making so the CE is not wholly intact.
