memory

• What is memory?


  Human memory is mostly defined as the process by which we 'retain information about events that have happened in the past'
• What is duration?


  The length of time information can be held in memory.

  STM= 18-30 seconds

  LTM= potentially a lifetime
• what is capacity?


  The maximum amount that can be contained in the memory.

  STM= 5-9 items(7+/-2)

  LTM= unlimited
• What is coding?


  How information is stored in the memory.

  STM codes acoustically

  LTM codes semantically
• Research into capacity of STM


  Jacobs and Jacob 1887 had participants listen to digits called an where told to recall immediately, when they got the correct answer the length increased until they got it wrong. they concluded that an average person is able to store 9 digits in their STM.(Digit span test)

  Miller 1956 conducted similar experiments and concluded that on average, participants recalled 7 items with a range of 5-9.

  Conclusion: Capacity of STM is 7+/-2 (“magic number”)
• Who discovered chunking and what is chunking?


  Miller discovered that we can remember 5 words as easily as we can remember 5 letters. Chunking allows us to group information to remember more than 7 individual u nits
• Research into STM duration


  Peterson and Peterson 1959 24 undergrads participants did 8 trials in which they were given a trigram (YHK) to remember. They counted backwards from a 3-digit number to prevent rehearsal. They were told to stop after 3, 6,9, 12, 15, 18 seconds. STM has a short duration without rehearsal.
• Research into LTM duration Bahrick1975


  392 participants from Ohio aged 17-74 were tested using their high school yearbooks from the participants or directly from their school. They had 2 conditions photo recognition using 50photos and free recall using names.

  <15 years after graduation = 90% accuracy for photo recognition & 60% accuracy for free recall (of class members names) >48 years = 70% photo recognition & 30% accuracy for free recall
• Research into coding Baddeley 1966


  Participants were shown the original words and asked to recall them in the correct order. When they recalled immediately after hearing it (STM) they tended to do worse with acoustically similar words (more confusion, makes recall difficult)– suggesting that info is coded acoustically in STM.

  When asked to recall the word list after a time interval of 20 mins they did worse with the semantically similar words (more confusion, makes recall difficult) – suggesting that info is coded semantically in LTM.
• Was artificial stimuli used during the research?

  One weakness is the use of artificial stimuli in most of the studies such as word list and trigrams. Baddeley asked ppts to recall lists of unrelated words, a task that we would never have to do in real life. The task had no meaning to participants. Therefore the study lacks external validity and that the findings cannot be used to explain how we code memories in real life. This limits the usefulness of this study when investigating memory.
• Can Peterson and Peterson study be easily replicable?


  A strength is that Peterson & Peterson’s study was highly controlled and took place in a laboratory of Indiana University. As a result Peterson & Peterson had a high degree of control for extraneous variables, which makes their procedure easy to replicate to test reliability.
• Does Bahrick's study have ecological validity?


  It could be argued that Bahrick’s study has high levels of ecological validity as the study used real‐life memories. In this study participants recalled real‐life information by matching pictures of classmates with their names. Therefore, these results reflect our memory for real‐life events and can be applied to everyday human memory.
• Did Miller specify the amount of chunk?

  Although Miller’s (1956) theory is support by psychological research, he did not specify how large each ‘chunk’ of information could be and therefore we are unable to conclude the exact capacity of STM. Consequently, further research is required to determine the size of information ‘chunks’ to understand the exact capacity of STM.
• Is there any counter research for Miller's research?


  Cowan reviewed other memory research and discovered that the average capacity of STM is 4 items, suggesting that Miller may have over-estimated the amount of information STM can hold. This suggests that Miller’s initial research may be flawed and that STM may hold around three items less than the 7 originally proposed.