Lesson 1 - Coding, Capacity, and Duration of STM and LTM Flashcards
What is the Short Term Memory (STM)?
Short term memory is a memory store that allows the recall of information for a period of several seconds without rehearsal.
What is Long Term Memory (LTM)?
Long term memory is a memory store that enables us to recall information from the more distant past.
What are the 3 main differences between LTM and STM?
Duration
Capacity
Coding
What is the duration?
It is a measure of how long information can be stored for.
What is the capacity?
The measure of how much information can be held or stored.
What is coding?
Coding is the form in which information is stored in the memory.
There are 3 possible ways of coding:
Acoustic,
Semantic,
Visual.
What are the 3 characteristics of the LTM?
Duration: A lifetime
Capacity: Infinite
Coding: Semantic
What are the 3 characteristics of the STM?
Duration: 18 seconds
Capacity: 7+-2 items
Coding: Acoustic
Who did the study on STM duration?
Peterson and Peterson (1959)
What was the methodology of Peterson and Peterson’s study?
There were 24 undergraduate students.
They were presented with a consonant trigram (e.g. GFP).
After counting to different numbers (3, 6, 9, 12, 15, 18) and then were told to recall the consonant trigram.
What were the results of Peterson and Peterson’s study?
90% of PPs could remember after 3 seconds.
20% after 9 seconds.
Less than 10% after 18 seconds.
Information disappears extremely quickly if it cannot be rehearsed.
Evaluation of Peterson and Peterson’s study - Lab experiment
It is a lab experiment so there is high control over variables.
Evaluation of Peterson and Peterson’s study - repeatable
This study is a repeatable study as it can be done on many participants very easily, due o it’s simplicity.
Evaluation of Peterson and Peterson’s study - Low ecological validity
Trying to remember consonant trigrams is a stupid task.
Who tested the duration of the long term memory?
Bahrick (1975)
What was the method of Bahrick’s study?
He tested using 400 American participants aged 17-74.
He asked if they could remember former classmates via pictures, matching names to pictures, and recalling names with no picture cue.
What were Bahrick’s findings?
Even after 48 years, when they were asked to link names and faces, accuracy was 70%.
When participants were asked to free recall the names of their classmates, and this had an accuracy of 30%.
This shows that long term memories can last a lifetime.
Evaluation of Bahrick’s study - Natural experiment
Bahrick’s study was a natural experiment that utilised meaningful material, so it has higher ecological validity than Peterson’s study.
Evaluation of Bahrick’s study - less control of the experiment
Due to the study being a natural experiment, the experimenter had less control, and it is likely that some of the names had since been rehearsed e.g. classmates could still be in touch.
Evaluation of Bahrick’s study - Issues with using names
Names are a very specific type of information, and they are repeated many times. It is likely that due to the regular rehearsal of them, they are easier to remember. Not all LTMs remain for a lifetime.
Who measured the capacity of the STM?
Jacobs (1887)
What was Jacobs’ method?
He developed the serial digit span technique. The researcher read out 4 digits and the participant was then asked to repeat it back. Another digit was then added, until the participant could not repeat it accurately.
What were Jacobs’ findings?
He found that about 9 digits and 7 letters were correctly recalled. This capacity increased with age until they were an adult. Digits may be easier to recall, as there are only 10 unique digits, but 26 letters.
Evaluation of Jacobs’ research - lacks ecological validity
Jacobs’ research lacks ecological validity, as random number and letter strings are not a realistic task. More meaningful information may be recalled better.
