Short And Long Term Memory Flashcards
What is long term memory?
Your memory for events that have happened
What’s the duration and capacity of LTM?
Last anywhere from 2 minutes to 100 years.
It potentially has unlimited duration and capacity
How is LTM coded?
Its coded semantically
What is short-term memory?
Your memory from immediate events.
How is STM measured?
Seconds and minutes, rather than hours and days
What’s the duration and capacity of STM?
Short duration - seconds, minutes
Limited capacity - 7+/-2
How is STM coded?
Tends to be coded acoustically
Why does STM need to be rehearsed?
They will disappear - short duration
What is capacity?
A measure of how much can be held in memory.
What can STM be referred to as?
The working memory
How is capacity represented?
It’s represented in terms of bits of information, such as number of digits.
What is coding?
The way information is changed so that it can be stored in memory (also encoding)
How does coding work?
Information enters the brain via the senses.
It is then stored in various forms, such as visual codes (like a picture), acoustic codes (sounds) or semantic codes (the meaning of the experience).
What is duration?
A measure of how long a memory lasts before it is no longer available.
What are the differences between STM and LTM?
Capacity - limited
Capacity - infinite
Duration - short
Duration - lasts forever
Coding - acoustically
Coding - semantically
How can the capacity of the STM be assessed?
Using digit span
What was a study to assess the capacity of STM?
Jacobs (1887) used digit span.
He found that the average span for digits was 9.3 items and 7.3 for letters.
Jacobs suggested that it may be easier to recall digits because there are only 9 compared to 26 letters.
What did Miller do?
Miller (1956) reviewed psychological research and concluded that the span of immediate memory is about 7 items - sometimes a bit more, sometimes a bit less.
He also found that people can recall 5 words as well as they can recall 5 letters - we chunk things together and can then remember more.
What are the evaluate points for capacity?
The capacity of STM may be even more limited
The size of the chunk matters
Individual differences
What is meant by the capacity of STM may be even more limited?
Cowan (2001) reviewed a variety of studies on the capacity of STM and concluded that STM is likely to be limited to about 4 chunks.
This suggests that STM may not be as extensive as was first thought.
Research on the capacity of STM for visual information (rather than verbal stimuli) also found that four items was about the limit (e.g. Vogel, 2001).
This means that the lower end of Miller’s range is more appropriate.
What is meant by the size of the chunk matters?
It seems that the size of the chunk affects how many chunks you can remember.
Simon (1974) found that people has a shorter memory span for larger chunks, such as 8-word phrases, than smaller chunks, such as 1-syllable words.
What is meant by individual differences?
The capacity of STM is not the same for everyone.
Jacobs also found that recall (digit span) increased steadily with age; 8 year olds could remember an average of 6.6 digits whereas the mean for 19 year olds was 8.6 digits.
This age increase might be due to a gradual increase in brain capacity, and/or it may be that people develop strategies to improve their digit span as they get older, such as chunking.
Who studied the duration of the STM?
Peterson and Peterson (1959)
What was Petersons study?
Used 24 students.
Each participant was tested over 8 trials.
On each trial a participant was given a consonant syllable and a three-digit number (e.g. THX 512).
They were asked to recall the consonant syllable after a retention of interval of 3,6,9,12,15 or 18 seconds.
During the retention interval they had to count backwards from their 3 digit number.