memory

• How are STM and LTM distinguished?

  STM and LTM are often distinguished in terms of their coding, capacity and duration.
• STM and LTM are often distinguished in terms of their coding, what does this refer to?

  Coding refers to the format in which information is stored in the various memory stores.

  - Information enters the brain via the senses (e.g. eyes and ears) and then is changed to another form so that it can be stored in memory. It can be stored in the form of sounds (acoustic), images (visual) or meaning (semantic)
• STM and LTM are often distinguished in terms of their capacity, what does this refer to?

  Capacity refers to the amount of information that can be held in a memory.
• STM and LTM are often distinguished in terms of their duration, what does this refer to?

  Duration refers to the length of time that information can be held in memory
• What is the Sensory Register? (Sensory Store)

  - how it works

  - environmental stimuli ( the sound of someone talking) enter the sensory register, comprising five separate stores for each sense

  - the primary stores are iconic (for visual information, initially encoded visually) and echoic (for sound-based information, initially encoded acoustically).
• sensory store coding

  depending on the sense that is picked up - e.g. visual, auditory or tactile. (modality specific)
• sensory store duration

  less than half a second
• sensory store capacity

  huge capacity (millions or receptors)
• What is Short-term memory (STM)?

  Short term memory is your memory for immediate events. It temporarily stores information received from the sensory register.
• How is information transferred from the sensory register to Short term memory?

  attention
• What happens if information is not attended to when it enters the sensory register?

  leads to spontaneous decay
• STM coding

  acoustically (Baddely 1966)
• STM capacity

  between 5 and 9 items (Miller 1946)
• STM duration

  18-30 seconds unless it is rehearsed (Peterson and Peterson 1959)
• How is information transferred from STM to LTM?

  prolonged rehearsal.e. verbally repeating a telephone number
• How is information transferred from LTM to STM?

  retrieval
• What is Long-term memory (LTM)?

  memory for events that have happened in the more distant past
• LTM coding

  semantically (Baddeley 1966)
• LTM capacity

  potentially unlimited
• LTM duration

  lifetime (Bahrick 1975)
• Baddely (1966) on coding in STM and LTM

  - procedure

  LABORATORY EXPERIMENT- participants were given four sets of words to learn- acoustically similar words (cat, cap, can) or dissimilar (pit, few, cow)- semantically similar (great, large, big) or dissimilar (good, huge, hot).- they were required to recall the words in the original order either immediately (testing STM) or after a 20-minute delay (testing LTM)
• Baddely (1966) on coding in STM and LTM

  - findings

  - immediate recall worse with acoustically similar words -> indicates acoustic coding in short-term memory (STM)

  - recall after 20 minutes worse with semantically similar words -> suggests semantic encoding in long-term memory (LTM)
• Why was immediate recall worse with acoustically similar words?

  STM causing acoustic confusion and becoming distracted by sounds of words thus not recalling in order
• Why was prolonged recall worse with semantically similar words?

  LTM causing semantic confusion and becoming distracted by meaning of words thus not recalling in order
• What is a strength of Baddeley's 1966 study on coding in STM and LTM?

  ✓ Showed differences between stores

  • showed differences between stores.

  • Later research showed that there are some exceptions to Baddeley's findings, e.g. types of coding.

  • However, the idea that STM uses mostly acoustic coding and LTM mostly semantic has stood the test of time.

  • This was an important step our understanding of the memory system, which led to the creation of the MSM.
• What is a strength of Baddeley's 1966 study on coding in STM and LTM?

  ✓ there is a high degree of control over extraneous variables

  • A strength of Baddeley's study is that there is a high degree of control overextraneous variables.• This allows us to see clearly that the IV (coding: semantic or acoustic) was what affected the DV (recall), improving the validity of results- This also means the experiment can be easily replicated
• What is a limitation of Baddely's 1966 study on coding in STM and LTM?

  ✘ it didn't use meaningful material.

  • A limitation of Baddeley's study is that it didn't usemeaningful material.• The words used in the study wereartificialhad no personal meaning to participants. When processing more meaningful information, people may use semantic coding even for STM.• This means that the results of this study have limited application in the real-world. We should be cautious about generalising the findings to different kinds of memory task.
• Baddeley et al. (1975)

  procedureLAB EXPERIMENTusing a dual task paradigm.-participants engaged in separate visuo-spatial sketch pad tasks - tracking a moving point of light and mentally navigating a capital 'F.
• Baddeley et al. (1975)

  results• Participants found it harder to complete two visual tasks at the same time than to complete the visual and verbal task.

  • The greater difficulty is because both visual tasks compete for the same limited resources, but when doing a verbal and visual task simultaneously, there is no competition.
• Jacobs (1887) on capacity of STM

  - procedure

  LAB EXPERIMENT• Used a digit span - researcher read four digits and increased until the participant could not recall the order correctly immediately.
• Jacobs (1887) on capacity of STM

  - findings

  • Digits = 9.3

  • Letters = 7.3
• What is a strength of Jacobson's (1887) study on capacity of STM?

  ✓ Replication of Jacob's study

  • Older studies often lackedadequate controls, e.g. , some participants' digit spans might have been underestimated because they were distracted during testing (confounding variable).• However, Jacob's findings have been confirmed and validated by other, better controlled studies since.• This suggests that Jacob's study has 'stood the test of time' and is a valid test of digit span in STM.
• Miller (1946) on capacity of STM

  - procedure

  • made observations and noted that the span of immediate memory is about 7 items.

  • For example, he noted that people can count 7 dots flashed on a screen but not many more. The same is true if you ask people to recall musical notes, words or even letters.
• Miller (1946) on capacity of STM

  - findings

  - STM span is approximately 7 items (plus or minus 2).

  recall improves with chunking - organizing data into meaningful groups.

  Example: Transforming BBCCAITVAARAC into BBC, CA, ITV, AA, RAC, which occupies only 5 memory slots.
• What is a strength of Miller's 1946 study on capacity of STM?

  ✓ it has many practical applications.

  • A strength of research into the capacity of STM is that it has manypractical applications.• Research into chunking laid the foundations for the postcode system we use in the UK today.• Baddeley discovered that if the initial letters of a postcode made up something meaningful (e.g. BS for Bristol) it made it easier to remember.• This shows how research into the capacity of STM has helped improve the efficiency of memory in a real life situation.
• Peterson and Peterson (1959) on duration of STM

  - procedure

  LABORATORY EXPERIMENT• Sample of 24 undergrad students.• Peterson and Peterson gave participants 'nonsense trigrams' (for example CKX), which they had to recall after a retention interval of varying amounts of time from 0-18 seconds.• On presentation of each trigram, they were required to verbally count backwards in threes from a specified number to prevent participants rehearsal
• Peterson and Peterson (1959) on duration of STM

  - findings & conclusion

  • After 3 seconds, 80% recalled correctly.

  • After 18 seconds, fewer than 10% of trigrams were recalled.
• Peterson and Peterson (1959) on duration of STM

  - conclusion

  • Rehearsal gotprogressively worseas the delay grew longer.• This suggests that the duration of STM is approximately 18 (to 30) seconds if rehearsal is prevented.
• What is a limitation of Peterson and Peterson's 1959 study on duration of STM?

  ✘ Use of artificial stimulus

  • A limitation of Peterson and Peterson's study is theartificial stimulus.• Recalling trigrams does not reflect most everyday memory activities where what we are trying to remember is meaningful.• On the other hand, we do sometimes try to remember fairly meaningless things, such as phone numbers, so the study is not totally irrelevant.• This means the study lackedecological validityas it may not be possible to generalise findings to real-life.
• Bahrick et al (1975) on duration of LTM

  - procedure

  FIELD EXPERIMENT to explore memory retention, graduates aged 17 to 74 from an American high school.Tasks:Photo recognition: participants selected former classmates from 50 graduation photosFree recall: Participants named classmates without visual aids.