Memory

Memory

1. Short term memory

   • Duration = 18 - 30 seconds
     • Peterson & Peterson (1959) - Shown nonsense trigrams and asked to recall them after 3, 6, 9, 12, 15 or 18 seconds. count backwards in 3's during the pause (interference task) to prevent them from reciting the letters.
       • After 3 seconds participants recalled 80% correctly
       • After 18 seconds participants recalled only 10% correctly
       • Reliable. Lab experiment - lacks ecological validity. Participants saw many trigrams - confusion?
   • Capacity = 7 +/- 2
     • Jacobs (1887) - presented with a string of letters or numbers, participants had to repeat them back in order, amount of numbers of letters carried on increasing until the participant failed to recall them correctly.
       • participants could recall 7 letters and 9 digits. Capacity increased with age during childhood.
       • Artificial - lacks ecological validity. Lots of sequences - confusion?
   • Encoding = Acoustic
     • Baddeley (1966) - Participants were given four sets of words either: acoustically similar, acoustically dissimilar, semantically similar or semantically dissimilar. participants were asked to recall the words either immediately or after a 20 minute task.
       • participants had problems recalling acoustically similar words immediately. If recalling after an interval they had problems with semantically similar words.
       • Lacks ecological validity. Other types of LTM and encoding that they do not consider. independent groups - participant variables.

2. Long term memory

   • Encoding = Semantic
   • Duration = Lifetime
     • Bahrick (1959) - 392 people asked to: List the names of their ex-classmates (free-recall test). Shown photos and asked to recall the names of the people shown (photo-recognition test). Given names and asked to match them to a photo (name-recognition test).