Short term memory

Short term memory

1. Duration

   • Short term memories don't last long about 18-20 seconds.
     • Verbal rehearsal can help transfer memories into the LTM.
   • Peterson&Peterson
     • They use 24 students and showed them trigram while they had to count back from a certain number. The time between the recall varied: 3,6,9,12&18 seconds.
       • They found people remembered about 90% when there was only a 3 second interval and only 2% when there was an 18 second interval.
         • Other case studies (Nairne)1999 found that items could be recalled after 96 seconds

2. Capacity

   • The capacity of short term memory is often measured using the digit span technique. Miller concluded that the span of the immediate memory is 7 and concluded thatpeople can recall more if they're chunked together
   • Jacobs
     • Jacobs used this technique to assess the capacity of STM finding that average span for digits was 9.3 itwms and for letters it was 7.3 items.
   • Baddeley
     • The technique chunking maximizes the efficenty of memory. Baddeley found that if the initial letters of the postcodes made up something meaningful it made it easier to remember. The numbers were best remembered if they were placed between the city name and random letters.

3. Encoding

   • Memory is usually encoded through acoustic coding which involves coding information in terms of how it sounds
   • Baddley
     • Baddley tested the effects of acoustic and semantic similarity on short term and long term recall. He gave people list of words which were acoustically similar or dissimilar and words that were semantically similar or dissimilar.
       • He found that people had difficulty remembering acoustically similar words in the STM but didn't have this difficulty with remembering semantically similar words.