Memory Flashcards
(129 cards)
What is duration ?
The length of time information can be stored in memory
What is capacity ?
The amount of information that can be stored in memory
What is coding ?
Memory encoding is a process by which the sensory information is modified and stored in the brain.
The most common forms are visual, acoustic and semantic.
What are the different types of memory stores ?
Sensory memory (SM)
Initial contact for stimuli.
Short term memory (STM)
The information we are currently aware of or thinking about.
Long term memory (LTM)
Continual storage of information which is largely outside of our awarenes
What are the capacity’s of the different types of memory stores ?
SM: has a very large
capacity
STM: has a limited capacity
of 7+/-2 items
LTM: has a potentially
unlimited capacity
Who came up with the digital span technique ?
Jacobs 1887
Jacob’s research on capacity :
He was one the first to use the digit span technique to assess the capacity of STM.
He found the average span for numbers to be 9.3 items
For letters the average decreased to 7.3 items
Miller’s magic number :
George Miller (1956) reviewed psychological research +concluded that ’the magic number is 7 plus or minus two.’
He found people could recall around 7+/-2 items.
Miller’s chunking :
Miller argued that our capacity for remembering information can be increased if we chunk items together.
If we find links between information and group them together then capacity can be increased.
Research into capacity - overestimation of the STM capacity :
Limitation
Cowan (2001) conducted a review of research and concluded that the capacity of STM is closer to 4 chunks of information.
This estimate falls towards the lower end of Miller’s suggested capacity of 5, suggesting that 4 may be a more appropriate “Magic Number” than 7.
However, it is important to consider that memory can be influenced by individual differences, which may make it challenging to draw universal conclusions in this area of research.
Research into capacity - absence of specification regarding the size of a chunk.
Limitation
Simon (1974) discovered that individuals have a smaller STM capacity when dealing with larger chunks, such as 8-word phrases, compared to single syllable words.
This suggests that Miller’s explanation alone is not sufficient to fully account for the capacity of STM.
However, despite this limitation, the research does support the perspective that STM does possess a limited capacity.
Research into capacity - capacity isn’t uniform for everyone
Limitation.
The presence of individual differences impact the results.
Jacobs’ study demonstrated that digit span recall consistently increased with age. On average, 8-year-olds remembered 6.6 digits, while 19-year olds remembered 8.6 digits.
This suggests that brain capacity may increase with age or that individuals develop improved strategies to enhance their digit span.
Therefore, caution should be exercised when generalising research findings on capacity, as age is an individual difference which influences the capacity of STM.
Research into capacity - lack of ecological validity
Limitation
Due to the artificial settings in which the research is conducted.
Studies by Jacobs and Miller, utilised meaningless words, numbers, and objects to test participants’ recall, which does not accurately reflect how memory is typically used in real-world contexts.
In everyday life, memory often carries much more personal significance, such as remembering people’s birthdays or recalling daily activities.
Therefore, as these tasks lacked mundane realism, the results from laboratory experiments may only be cautiously generalised to real-world scenarios.
Duration of memory in different types of memory stores :
SM: Less than one second
STM: Approximately 18-30 seconds
unless information is rehearsed
LTM: Potentially lasts infinitely
Peterson and Peterson (1959) STM - aim
To investigate the duration of STM
Peterson and Peterson (1959) STM - participants
24 university students
Peterson and Peterson (1959) STM - procedure
On each of the 8 trials participants were given a consonant trigram and a three-digit number. They were asked to recall the consonant syllable after intervals of 3, 6, 9, 12, 15 or 18 seconds.
To prevent rehearsal ppts were asked to count backwards from their 3-digit number.
Peterson and Peterson (1959) STM - findings + conclusion
After 3 seconds recall accuracy was 80%
After 9 seconds recall accuracy was 20%
After 18 seconds recall accuracy was less than 10%
The duration of STM is less than 18 seconds.
Bahrick et al (1975) LTM - aim
To investigate the duration of LTM
Bahrick et al (1975) LTM - participants
392 ppts,
USA,
17-74 years old
Bahrick et al (1975) LTM - procedure
Tested photo recognition and free name recall from the participant’s high school yearbook.
Photo recognition: Had to recall the names of students from 50 photos in the high school yearbook.
Free recall: Asked to list the names they could remember from their graduating class.
Bahrick et al (1975) LTM - findings + conclusions
Photo recognition
Ppts tested within 15 years of graduation were 90% accurate
After 48 years recall declined to 70%
Free recall
After 15 years 60% accurate
After 48 years 30% accurate
Conclusion
The duration of LTM can last a very long time.
Research into duration - may not have been measuring trace decay, but displacement instead
It’s a limitation of the Peterson & Peterson study. This lowers the construct validity of the research.
participants were asked to engage in a distraction task of counting backwards in 3s or 4s.
This complex task could have overwritten the trigrams and resulted in displacement rather than solely preventing rehearsal.
Reitman (1974) conducted a study using auditory tones instead of numbers so displacement would not occur and found that the duration of STM was longer.
This suggests that the validity of the results from Peterson & Peterson was compromised due to methodological limitations.
Research into duration - Peterson & Peterson study results lack ecological validity
Limitation
The stimulus material used in the task was artificial, lacking mundane realism.
Ppts were asked to memorise trigrams, which does not reflect real-life examples of memory.
In real-life settings, people are required to remember personal events and birthdays, which hold greater personal significance than nonsensical syllables.
However, in certain everyday situations, we do need to remember meaningless information like phone numbers or postcodes.
In these instances, the trigram task may be representative of real-life memory demands.