Short and long term memory Flashcards
What were the first experimental studies on memory?
Ebbinghaus and his nonsense syllables - CVC trigrams which contained no meaning so memory not aided by familiarity
Read aloud, tested, read aloud again - continued for over 60 trials until all memorised correctly
What was the second stage of Ebbinghaus’s memory experiments?
Attempted to relearn list after time passed e.g. 24hrs
Time needed to relearn decreased significantly depending on number of repetitions prior to time interval (application in revision for exams)
What was Ebbinghaus’s Savings Method?
Technique to measure how much learning is saved between sessions
e.g. if first session took 20 trials to learn list, but after 15 minutes it took 2 trials to re-learn, index of retention=20-2=18 i.e. 90% - this means that when time between learning and re-learning is only 15 mins, we retain 90%
When interval longer, e.g. 6 hours, he needed 15 trials in second session so index = 20-15=5 i.e. only 25% remembered after that time
So longer leave between studying and taking test, more forgetting will occur
What does Ebbinghaus’s forgetting curve demonstrate?
Forgetting is rapid over first hour, but decline is less significant as time increases beyond that point
Pattern suggests existence of STM and LTM stores - high level of retention short-lived in first hour, lower but more stable level in long-term (not all info enters LTM)
What does Atkinson and Shiffrin’s Multi-Store model of memory suggest?
Memory consists of 3 linked storage systems, with memory duration increasing as go through
Sensory memory –> STM –> LTM
What is meant by sensory memory?
Info received from senses (echoic, haptic, iconic) - preliminary memory, lasts milliseconds unless we actively pay attention and process it, at which point it can pass into STM
What do Atkinson and Shiffrin suggest regarding STM?
Info in STM store can be retained for several seconds, and we need to engage in rehearsal and coding in order to remember it for longer e.g. to remember a phone number we would probably code it as chunks of numbers and rehearse the series in our heads
This increases STM duration and also likelihood that info will pass to LTM
What is long term memory in the multi-store model?
Information can only reach here through active processing of STM - once here we have a stable and essentially permanent memory store, from which we can retrieve info via short term memory
What was Sperling interested in?
Sensory memory stores, particularly their contribution to eyewitness testimonies - when an event happens we cant process all of it but we do retain some details in sensory memory
How reliable is this, and how much info can actually be remembered accurately?
What were Sperling’s Total Report experiments?
Used a letter chart, briefly presenting visual pattern to subjects for 5-500msec
Participants asked to recall and write down as many letters as possible, with aim being to remember all of them; measured how many actually remembered
Performance was poor - only about 33% able to be recalled - iconic memory has a limited capacity
But Sperling believed this capacity was being underestimated, so set up a different experiment
What was Sperling’s second experiment?
Similar to first but involving PARTIAL REPORT - participants only had to remember part of original array
Part determined by brief cue (tone of high, medium or low frequency) immediately AFTER visual pattern
Playing tone after relies on undirected attentional focus and the small amount of memory without time to prep - the key is that recall, not perception, is now more focused
Also manipulated delay between letters and tone to see how long we retain iconic memory for
What were the results of Sperling’s second experiment?
As delay increased, recall became less - iconic memory is reliant on time elapsed before testing
When interval was 1sec, recall was the same as for the total response procedure i.e. at this point the tone is not benefiting in any way
In summary, what did Sperling’s experiments illustrate?
Sensory registers are rich in content (memory of 80-90% when tested immediately) but VERY BRIEF in duration - illustrates important of interviewing eye witnesses as soon as possible after an event before forgetting (and false memories)
What are the key characteristics of STM?
Limited capacity (5plus or minus 2), limited duration, fragile storage (info only brief unless rehearse and actively process), functions for control of behaviour, transfer to LTM, retrieval from LTM
What are the key characteristics of the LTM?
Virtually unlimited capacity and duration unless pathology, secure storage (still requires some rehearsal for more accurate recall), functions for storage and retrieval
