Research on memory

Research on memory

1. Duration

   • STM
     • Peterson and Peterson
       • 24 students and the trigram test e.g. THX 512 and they were asked to recall the consonant syllable after a retention interval of 3, 6, 9 seconds etc.
         • PPS had 90% accuracy after 3 sec, 20% at 9 secs and 2% after 18 secs. Suggesting that STM has a very short duration less than 18 seconds
           • LACKS ECOLOGICAL VALIDITY- as stimulus material was artificial
           • The findings may be explained by displacement rather than the material only lasting a short time in STM (spontaneous decay) as counting numbers in their STM that displaced the syllables
   • LTM
     • Bahrick et al
       • 400 people at various ages were tested in a school year book experiment and were asked to recall the names of people in their graduating class.
         • PPs tested with 15 years of graduation =90% accuracy, 48 years declined to 70% and free recall was about 60% at 15 years and 30% after 48 years.
           • has more Ecological validity than the first study

2. Capacity

   • Jacobs digit span
     • Making PPs listen to a set of numbers and then recall them if they go it right and the number of numbers would increase each time.
       • mean span for digits was 9.3 items and for letters was 7.3
   • Miller
     • Meta-analysis and writing an article about STM capacity
       • Lead onto miller finding out that the capacity of the STM is 7 +/- 2
         • however as miller may have over-estimated the capacity if the STM Cowan reviewed research on the topic and found the STM capacity is more likley to be about 4 chunks rather than 7

3. Encoding

   • Baddeley
     • Acoustically similar/dissimilar groups and semantically similar/dissimilar groups
       • Each given trial of 5 words and after an interval they were asked to identify the correct 5 words and place them in order out of 10 given
         • Results for STM had acoustically dissimilar words as lowest recall. Suggesting STM are encoded acoustically
           • When LTM was tested (interval of 20 mins) groups with semantically dissimilar words had the lowest recall. Suggesting LTM encodes words semantically
             • Too short of an interval and not being completely representing the LTM
             • Not ecologically Valid, thus reducing generalisability