memory Flashcards
Capacity
The amount of information that can be held in your memory
Encoding
How sensory input is changed into a format for use in memory.
sound , vision and meaning are all encoded differently
Duration
Length of time information remains in your memory
Short-term memory
Duration - 18 to 30 seconds
Capacity – 5 to 9 items
Encoding - mainly acoustic
Long-term memory
Duration – unlimited
Encoding - semantic
Capacity – unlimited
Long-term memory
Duration – unlimited
Encoding - semantic
Capacity – unlimited
Research on duration of the long-term memory - Bahrick
Bahrick et al
329 us ppts —> 17-74 years old
1) photo recognition from yearbooks with 50 photos
2) free recall test where participants to recall all the names of their graduating class
Findings of research on duration (LTM) after 15 years
90% photo recognition
60% free recall
Findings of research on duration long-term memory after 48 years
70% photo recognition
30% free recall
Shows that long-term memory may last up to a lifetime for some material
Research on duration for the short-term memory
Peterson and Peterson
24 students
Used trigrams like BNT
Had to count backwards to prevent rehearsal
Research on duration for the short-term memory
Peterson and Peterson
24 students
Used trigrams like BNT
Had to count backwards to prevent rehearsal
Findings on research of duration (STM)
After 3 seconds recall was 80%
After 18 seconds recall was 3%
This shows that short-term duration is 18 seconds unless we repeat or rehearse the information
Research on coding
Baddely
Gave different lists of word to 4 groups of ppts to remember
Group 1- acoustically similar
Group 2- acoustically dissimilar
Group 3- semantically similar
Group 4 - semanically dissimilar
Participants were shown the original words and asked to record them in the right order
Findings of the research on coding
Tended to do worst on acoustically similar
They tended to do worst recalling from their long-term memory after the interval of 20 minutes for the semantically similar words
This suggests that information is
coded acoustically in stm
Coded semantically in LTM
Research on capacity
Jacobs
Measured digit span
The researcher reads out 4 digits which participants recall in the right order then the researcher reads out 5 digits then 6 digits to be recalled until it cannot be recalled correctly
Research on capacity findings
Mean span for digits – 9.3 items
Means span for letters - 7.3 items
Research on capacity
Miller
Made observations of every day practice
He noted things come in sevens e.g days of the week and deadly sins
So he thought STM capacity is 7+/-2
We recall 5 words/letters easier because we chunk this into groups
Evaluation on coding
Strength – baddeleys study identifies a clear difference between both memory stores , Led to msm
Weakness – lacks mundane realism as they use artificial stimuli with no real meaning to participants
Don’t relate to every day life so limited application
So if it was meaningful participants may use semantic coding even for simple tasks
Evaluation on capacity
Jacob’s study strength - can be replicated easy but however as it is an old study it can be critiqued for lacking adequate controls
So participants could’ve been underestimated due to extraneous variables from distractions
Counterpoint – better controlled studies have replicated Jacob study and got similar results so Jacob study is a valid test
Evaluation coding miller
Weakness - Overestimated short-term memory capacity
(Cowan 2001) found capacity of short-term memory is around 4+ or - 1
This suggest the lower end of the Millers Estimate of 5 items more appropriate
Evaluation of duration of STM
Peterson and Peterson
Weakness – artificial stimuli of trigrams we don’t study every day
Counterpoint -Not completely irrelevant as we do sometimes try to remember meaningless material
Lacks external validity as it doesn’t reflect every day memory
Evaluation of duration study -LTM
Bahrick study
Strength – high external validity as they investigated meaningful memories it doesn’t have a limited application
When studies conducted on long-term memory with meaningless pictures recall rates lowered ( Shepherd 1967)
His study reflects the real estimate of LTM‘s duration
Who discovered types of LTM
Tulving 1985
Implicit / declarative memory
People are not aware of these memories
Procedural
Explicit / declarative memories
Memories people are aware of
Semantic and episodic
Episodic memory
Our ability to recall events and episodes from our life
We recall memories such as events /people /objects to do with our life and we remember when they occurred
Hippocampus
Semantic memory
Our library / dictionary
Our knowledge of the world
Includes facts and knowledge of what words and concepts mean
Less vulnerable to distortion and forgetting
Less personal
Temporal lobe
Procedural memory
Knowledge of how to do things
Includes our memories of learned skills
We usually recall these memories without making a conscious effort
Cerebellum
Procedural memory
Knowledge of how to do things
Includes our memories of learned skills
We usually recall these memories without making a conscious effort
Cerebellum
Strength of types of LTM - clinical evidnce
Clive wearing / HM
Episodic memory —> severely damaged
Semantic memory —]relatively intact
Both patients still knew how to speak / play piano / walk/ what a dog was etc
Supports Tulvings view that there are different memory stores
One store can be damaged , whereas the others are unaffected
Counterpoint to clinical evidence for types of LTM
Case studies unique to a small amount of people send its hard to replicate the findings and control variables
As researcher can’t control how they’re memory was like before the injury and not everyone has the same brain injury as HM and Clive therefore failing to generalise the findings to the population
Ideographic research
Conflicting neuroimaging evidence for types of LTM
Weakness
Buckner and petersen
Reviewed evidence regarding location of semantic and episodic memory
They found semantic memory is located LEFT SIDE OF PREFRONTAL CORTEX
And episodic memory on THE RIGHT SIDE OF THE PREFRONTAL CORTEX
However other research swaps the types of LTM with the sides of the prefrontal cortex
