Memory Flashcards
What is short term memory?
Short term memory stores and allows recall of information for a period of several seconds.
What is long term memory?
Stores and enables us to recall information from the more distant past.
In which 3 ways are STM and LTM different?
Duration, capacity and encoding
What is duration?
A measure of how long information can be stored for or how long it lasts.
Who investigated the duration of STM?
Peterson and Peterson.
- 24 undergraduate students were presented with a consonant trigram.
- They were then asked to count backwards in threes to stop them repeating/rehearsing the consonant trigram.
- After intervals of either 3, 6 ,9, 12, 15 or 18 seconds, participants had to stop counting and repeat the trigram.
What were the results of Peterson and Peterson’s study?
- Participants could remember about 80% of trigrams after 3 seconds.
- 20% after 9 seconds
- Less than 10% when there was a 18 second interval.
- The maximum STM duration is about 18-30 seconds.
Evaluate Peterson and Peterson’s study on the duration of STM.
Strengths
1) It is a lab experiment where variables can be tightly controlled e.g how many trigrams are presented. The procedure can also be replicated to test if results are reliable.
Weaknesses
1) Trigrams are unrealistic things to remember. Therefore it has low ecological validity.
2) Trigrams presented on earlier trials may have cause confusion when participants came to remember trigrams in later trials.
Who investigated the duration of LTM?
Bahrick et al.
- Tested how well about 400 American participants could remember their former classmates by asking them to identify pictures, matching names to pictures.
What were the results of Bahrick’s study?
- Even after 48 years, when asked to link names and faces, accuracy was at about 70%.
- However, when participants were asked to free recall to names of their classmates, accuracy was about 30%
- This backs up the idea that long term memories can last a lifetime.
Evaluate Bahrick et al’s study.
Strengths
- This was a natural experiment with meaningful material so has higher ecological validity because remembering names is an everyday task.
Weaknesses
- It only looked at a specific type of information (names of classmates). This type of information is particularly meaningful and regularly rehearsed. Not all LTM’s remain there for a lifetime.
- Because it is a natural experiment, the experimenter had less control of the IV thus it’s likely some of the names had been rehearsed e.g if classmates were still in touch. This would be a confounding variable, making results potentially invalid.
What is capacity?
A measure of how much information can be held or stored.
How did Jacobs investigate the capacity of the STM?
- Jacobs developed a serial span technique.
- The researcher read out 4 digits and the participant was asked to repeat it back.
- Another digit was added until the participant could not repeat back the digit string accurately.
What were the results of Jacobs study?
- On average about 9 digits and 7 letters were correctly recalled.
- This capacity increased with age.
- This may be because there is a gradual increase in brain capacity, and/or because people develop strategies to improve their digit span, such as chunking.
- Digits may have been easier to recall as there are only 10 digits to remember, compared to 26 letters.
Evaluate Jacob’s study.
- Jacob’s research lacks ecological validity- learning random lists of numbers is not a realistic test of STM.
- Given Jacob’s study was conducted so long ago we also cannot be sure that extraneous variables were controlled.
What did Miller conclude?
- He concluded that the STM has a capacity of 7+-2 items.
- He also said that memory capacity can be increased through a process called chunking.
Which 3 possible ways can information be coded?
- Acoustic coding: storing information in terms of the way it sounds.
- Semantic coding: coding information in terms of its meaning.
- Visual coding: storing information in terms of the way it looks.
How did Baddely investigate coding?
- Participants were shown a sequence of 5 words under one of the four conditions, and then immediately had to write them down in order.
- Acoustically similar, acoustically dissimilar, semantically similar, semantically dissimilar
What were the results of Baddely’s experiment?
- When tested immediately, participants were least accurate with the acoustically similar words- they commonly got them muddled.
- When tested 20 minutes later, participants were least accurate with semantically-similar words.
- In conclusion, information is normally coded acoustically in the STM and semantically in the LTM.
Evaluate Baddely’s experiment.
- Low ecologically validity- the words were a meaningless list, and perhaps semantic coding is only used when information is more meaningful.
- This means that the results have limited application to real life.
Who first introduced the multi-store model?
Atkinson and Shiffrin in 1968
What are the 3 unitary stores of the multi-store model?
1) Sensory register or sensory memory
2) Short term memory
3) Long term memory
What does the multi-store model work?
1) Information is detected by the sense organs and enters the sensory memory.
2) If attended to this, information enters the STM.
3) Information from the STM is transferred to the LTM only if that information is rehearsed.
4) If rehearsal does not occur, then information is forgotten, lost from STM through the processes of displacement or decay.
What are the 5 separate sensory stores?
1) Iconic store- Where visual images are kept for a short period.
2) Echoic store- Where auditory senses are kept for a short period.
3) Haptic store- Retains physical senses of touch and internal muscle tensions.
4) Gustatory store: Related to taste information
5) Olfactory store: Related to smell
What is the duration of the sensory register?
Less than half a second (250 milliseconds)
Describe how Sperling investigated the sensory register.
- In a lab experiment, pps were shown a grid with three rows of four letters for 50 milliseconds.
- They had to then immediately recall either the whole grid, or a randomly chosen row.
What were the results of Sperling’s experiment?
- When pps were asked to recall a particular row, pps could recall on average, 3 out of 4 items, no matter which row had been selected.
- In conclusion, as the pps didn’t know which row was going to be selected by still managed to recall 3/4 letters in a row, suggests that the whole grid was held in their sensory register.
Evaluate Sperling’s experiment.
- Because it was a lab experiment, it was highly scientific.
- The variables could be controlled, and it would be easy for someone to replicate the study.
- However the artificial setting of the study means it lacks ecological validity-people don’t normally have to recall letters in response to sound, so the results might not represent what would happen in the real world.
What is the primacy effect?
- The primacy effect is when we are more likely to remember words at the beginning of a list because they are the first words that we see, and we have enough time to rehearse them.
- This increases the likelihood that they will move into the LTM.
What is the recency effect?
- The recency effect is when we are most likely to remember words from the end of the list as they were still held in our STM.
Explain Murdock’s study and how it proves the recency and primacy effect.
- Murdock asked participants to learn a list of words that varied in length from 10 to 40 words and free recall them.
- Each word was presented for one or two seconds.
- He found that the probability of recalling any word depended on its position on its list.
- Words presented either early in the list or at the end were more often recalled, but the ones in the middle were more often forgotten. This is known as serial position effect.
- Murdock suggested that words early in the list were put into LTM (primacy effect) because the person has time to rehearse each word acoustically.
- Words from the end of the list went into the short term memory which can typically hold about 7 items.
Which case study supports the idea that STM and LTM are separate stores?
- H.M had an operation to remove the hippocampus from both sides of his brain to reduce the severe epilepsy he suffered.
- After the operation, HM’s personality remained intact and he could still recall a list of 6 words in order.
- This shows HM’s short term memory was still intact, but his surgery had left him unable to form new long term memories.
What are the strengths of the MSM?
1) Can explain primacy and recency effects.
2) Case studies support the idea that STM and LTM are separate stores.
3) Brain-scanning techniques have also supported the idea that long and short term memories are separate stores: Prefontal cortex was active during STM but not LTM tasks.
What are the weaknesses of the MSM?
1) The idea that all information needs to be rehearsed in order to move in the LTM is an oversimplification as MSM does not explain flashbulb memories.
- It doesn’t take into account that information more relevant to our lives is far easier to remember.
- Similarly if we do not fully understand a piece of information no matter how many times we rehearse it, it is unlikely it will stay in our LTM for a long period of time.
- Furthermore, we don’t need to rehearse information at all to form LTMs e.g Kulik and Brown found highly emotional, significant or shocking events are easily stored in our long term memories without any rehearsal.
2) Evidence suggests that the STM and LTM are not single stores.
- It is now believed that the STM can be divided up into 2 stores: one for visual information and another for auditory information.
- In support, patient K.F sustained brain damage from a motorbike accident which left him with a severely impaired STM for verbal information only (his visual STM showed no impairment)
- This suggests that K.F had damaged just part of his STM and therefore it is not a unitary store as the MSM argued.
3) Most studies supporting the MSM lack ecological validity.
- In most supporting studies participants asked to complete simple, unrealistic tasks, which didn’t test their memories in ways relatable to everyday life e.g random lists of words,digits, trigrams.
- In real life we tend to form memories related to meaningful information.
- This suggests that the MSM lacks external validity because supporting evidence may not reflect how the memory works in real life.
What are the three types of long term memory?
1) Episodic memory
2) Semantic memory
3) Procedural memory
What is episodic LTM?
- It is the memory that gives individuals an autobiographical record of personal experiences.
- The strength of episodic memories is influenced by: emotions present at the time memory is coded e.g traumatic events are often well recalled due to their high emotional content.
What is semantic LTM?
- This type of memory contains all knowledge (facts,concepts and meanings) the individual has learned.
- The strength of semantic memories is dependent upon the degree of processing occurring during coding.
What is procedural LTM?
- It is a type of implicit memory permitting individuals to perform learned tasks with little conscious thought e.g riding a bike.