Memory experiments/investigations

• Coding: converting info from 1 form to the other.
• Description: Alan Baddely- gave different lists of words to 4 gruops of participants, all different conditions
  • 1) Accoustically similar, e.g: cat, cab, can
  • 2) accoustically dissimilar: pit, few, cow
  • 3) semantically similar: great, large, big
  • 4)semangtically dissimilar:good, huge, hot
  • RESULTS: participants retrieved info better after told to recall immediately (STM recall). Recall worse with accoustically similar words, as they were asked to list them in the order they were said. Participants asked to recall 20 mins later (LTM)= Did worse w semantically similar words
  • Conclusion=> LTM coding is semantic

• STRENGTHS:
  • Baddeley had a very reliable experiment. replicated it 3 times, improving the procedures each time. He used the same lists of words, gave the participants the same amount of time and tested them in the same way. This is called following standardised procedures.improved the validity of his study by using controls. He added an interference task (writing down lists of numbers) before each trial to “block” the STM and make sure only LTM was being used. He also presented the words on slides because he didn’t want to disqualify people for having bad hearing.
  • Led to Baddely later realising that the multistore memory model was too simple=> led to him forming the Working memory model, which is more accurate.

• WEAKNESSES:
  • 72 people did the experiment, the accoustically similar group only had 15 people. This is a small number. the participants were all volunteers, which could mean that might have more people with parrticularly good memories who enjoy doing memory tests - not represantitive of people in general.
  • the study used quite arificial stimuli, instead of meaningful material=> no personal meaning to participants=> no semantic coding so no ecological validity, especially as it doesnt resemble irl.

• How much info can be held in memory.
• Joseph Jacobs (1887), developed a technique to measure digit span:
  • gave 4 digits, tehn each participant was asked to recall in the correct order outloud. If correct, researcher would read out 5 digits, etc until they get it incorrect. this would determine the individuals digit span.
  • RESULTS: mean for digits: 9.3. Mean for letters@ 7.3
• George Miller (1956), made observations for everyday practice: everything comes in 7s, eg, days, 7 deadly sins, etc.
  • Conclusion: capacity of STM= 7 (magic number) +/-2. Also noted that peoploe can recall 5 words and 5 letters by chunking: grouping sets of digits/letters into units/chunks.

WEAKNESSES:

• Joseph's experiment was conducted so long ago, when excperiments were not adequetely controlled, e.g: participantrs could have been distracted during the experiment=> idnt perform as well as hey could have. Results= invalid due to cofounding variables. However, other experiments do support the results of this experiment
• Miller might have also over-estimated the capacity of the STM. Cowan (2001), reviewd the research + suggested that the capacity was arojnd 4 chunks, which closer to Miller's lower estimate of 5 digits, rather than 7.

• STM: Margaret and Lloyd Peterson (1959): tested 24 undergrads in 8 trials. Each trial, the student was given a constant syllable (a triagram, e.g YCG) + were also given a 3-4 digit number. they were then asked to count backwards from that # then told to stop and recall the syllables. the counting down was done to prevent mental rehearsal of the syllable. tehy were told to stop and recall after a diff amount opf time each trial- 3,6,9,12,15,18 (retention interval)
• RESULTS: after 12s, only 25% could recall correctly. 12.5% @ 18s
• CONCLUSION: STM = short duration unless verbally rehearsed

• LTM: Harry Bahrik (1957): tested 392 rom ohio (17-74). Their highschool yearbooks obtained from them or schools.  tested on Photo-recognition test: consisting of 50 photos and free recall test: where they ahd to recall all the names of people in their year.
• RESULTS: participants who were tested within 15 years= about 90% accuaracy in photo recognition. After 48 years= recall declined to 70% Free recall after 15 years= 60%, 48 years= 30% accurate
• CONCLUSION: LT, can last a v long duration.

STRENGTHS:

• higher external validity in Bahrik's study: real life meaningful memories were studied. when meaningless memories were studies, results were less accurate, such as with Shepphard in 1967. However, because its so real, diff participants could have looked at their yearbook pis over the years and could have rehearsed in their memories.

WEAKNESSES:

• Peterson: stimuli material was artififcial. trying to remember constant syllables does not resemble activities irl where what we are trying to remmeber is meaningful. => study lacks external validity. however, it could be argued that we do try and remember meaningless things when remembering phone numbers.
• also, Peterson +Peterson only suggest 1 explanation for why we forget things: the memory trace simply disappears if we are not rehearsing it (spontaneous decay). However, another explanation could be that info in memory becomes diasplaced- as STM has a limited capacity and the newe info pushes out the old info