How are STM and LTM distinguished?
- Capacity
- Duration
- Encoding
What is capacity?
Capacity concerns how much data can be held in a memory store
Describe Jacobs’ study into capacity of STM
- Tested the capacity of STM using digit span
- He found that the average span for digits was 9.3 and 7.3 for letters
Describe Miller’s study into capacity of STM
- He reviewed psychological research
- He concluded that the span of STM is about 7 items =,-, 2
- He also suggested chunking improves the memory
Describe Cowan’s evaluation of capacity of STM
- He reviewed a variety of studies on the capacity of STM
- He concluded that STM is likely to be limited to about four chunks
Describe Simon’s evaluation of capacity of STM
- He found that people had a shorter memory span for larger chunks than smaller chunks
- Therefore, the size of the chunk matters
Describe Jacobs’ evaluation into capacity of STM
- He found that recall increased steadily with age
- 8 Year olds could remember on average, 6.6 digits while the mean for 19 year olds was 8.6
- Therefore, individual differences affect the capacity of STM
What is duration?
Duration is a measure of how long a memory lasts before it is no longer available
Describe Peterson and Peterson’s research into duration of STM
- They used 24 students
- Each was tested over eight trials
- They were given a consonant syllable and a three digit number
- After a retention interval of: 3, 6, 9, 12, 15 and 18 seconds, during which they were asked to count backwards from their three digit number, they were asked to recall the consonant syllable
- on average, 90% were correct after 3 seconds
- 20% after 9 seconds
- 2% after 18 seconds
Describe Bahrick et al’s study into duration of LTM
- They tested 400 people aged 17-74 on the memory of classmates
- First was a photo recognition test consisting of 50 photos, some from the participants high school year book
- Those tested within 15 years of graduation were about 90% accurate
- Those tested after 48 years were about 70%
- Second was a free recall test
- Participants were asked to list the names they could remember of those in their graduating class
- After 15 years recall was about 60%
- After 48 years recall was about 30%
Evaluate Peterson and Peterson’s research
Trying to memorise consonant syllables does not fully reflect most everyday memory activities. However, we do sometimes try to remember fairly meaningless things
This means that although the task was artificial, the study does have some relevance to everyday life
What is encoding?
The way information is changed so that it can be stored in memory
How can memory be encoded?
- Acoustically
- Visually
- Semantically
Describe Baddeley’s research into encoding
- He used word lists that were acoustically similar but semantically different and semantically similar but acoustically different
- This was to test the effects of acoustic and semantic similarities on STM and LTM
- He found that participants had difficulty remembering acoustically similar words in STM but not in LTM suggesting that STM is largely encoded acoustically
- He found that semantically similar words posed little problem for STMs but led to muddled LTMs suggesting LTM is largely encoded semantically
Describe Brandimote et al’s evaluation of encoding
- They found that STM may not be exclusively acoustic
- Participants used visual encoding in STM if they were given a visual task and prevented from doing any verbal rehearsal in the retention interval before performing a visual recall task
Evaluate Baddeley’s research into encoding
- Baddeley may not have tested LTM
-STM was tested by asking participants to
recall a word list immediately after hearing it
- LTM was tested by waiting 20 minutes so it is questionable as to whether this is really testing LTM
