Duration of STM
Who: Peterson & Peterson: Trigram recall test
Procedure: 24 students, asked to recall nonsense trigrams (AFC), interfrence task of counting back in 3's (330,337,334). Asked to recall trigram, time increased 3 seconds each time upto 18 seconds
Findings: 90% recalled trigram after 3 seconds interval, 2% after 18 seconds
Conclusions: STM duration lasts upto 18 seconds
AO2: lacks mundane realism, low ecological valdity, cannot be genrelised, high internal valdity, sample bias; 24 psychology students, age bias.
Duration of LTM
Who: Bahrick et al: Yearbook recall
Procedure: Four tests: 1. Free recall of names, 2. Photo recognition, 3. Name recognition and 4. Name to photo recognition
Findings: 90% of face and name recognition after 15 years, dropped to 80% for name and 40% for face after 48 years. Free recall was 60% accurate after 15 years, then 30% after 48 years
Conclusions: Recongntion is better than recall
AO2: high mundane realism, high ecological validity, low external validty, cannot be controlled, 17 year olds more likley to remember faces and names,
Capacity of STM
Who: Joeseph Jacobs: Digit span test
Procedure: Asked participants to recall digits, increasing the digit number by one each time.
Findings: That average digit span recall was 9.3, whilst letter recall was 7.3. Also adults were better (19 year old) had 8.6 span, whilst 8 year old had 6.6 digit span.
Conclusions: Capacity of STM is between 5-9 pieces of information
AO2: low mundane realism, high internal valdity, low external validty, demand characteristics
Who: Baddely: acoustic and semantic recall
Procedure: 4 lists of words: acoustically similar and dissimilar, semantically similar and dissimilar.
Findings: People were able to recall acoustic words in STM, and recall semantic (meaning of) words using LTM.
Conclusions: STM: Acoustic (sound) LTM: Semantic (meaning)
AO2: low mundane realsim, demand charcteristics, high internal validty