Capacity

Capacity

1. Short Term Memory

   • Jacob's Research
     • Participant is given 4 digits and is asked to recall in correct order
       • If participant is correct, increases to 5 digits etc
     • Average capacity was 5-9 items
     • Mean digits was 9.3 items, and Mean Letters was 7.3.
     • Limitation: Other Variables weren't controlled
       • Eg; Participants were distracted, so result's weren't valid.
         • However other research supports the validity
   • Miller's Research
     • Noted things came in 7's, so suggested Capacity of STM is 7 items, plus or minus 2.
     • Also noted people can recall 5 words as well as 5 letters, done by chunking
     • Limitation: Overestimated Capacity of STM
       • 'Cowan' concluded Capacity of STM is about 4 chunks, so lower end of Miller's estimate is more accurate.
   • Simon's Research
     • Regarded words as chunks
     • An entire phrase should be regarded as a chunk
     • Limitation: Lacks External Validity
     • When focused on number of words in the span, he found it increased from 7 words to 9, with 2-word phrases and 8-word phrases

2. Long Term Memory

   • Glanzer's Research (Recency Effect)
     • Participants were told words and had to recall them in order
     • Last 2/3 words are better remembered than the middle words - recency effect
   • Primacy Effect
     • Words at the start are well remembered
       • Those words were moved to LTM by rehearsal

3. Capacity is the amount of information that can be held in a memory store