Short Term Memory

Short Term Memory

1. Capacity

   • Limited Capacity
   • Immediate digit span - reading out a list of random digits and the participant to repeat them back in order
   • Miller (1956) people have a digit span of seven plus or minus two - Miller's magic number
     • Chunking occurs when we combine individual letters or numbers into a larger meaningful unit
   • Influence of long term memory can affect the capacity of STM
     • Bower and Winzenz (1969) - digits repeated become progressively easier
   • Reading aloud can affect cap. STM - performance is better
   • Rhythmic grouping - words chunked together acoustically
   • Pronunciation Time can affect cap. STM

2. Duration

   • Has brief duration
   • Baddely et al. (1975)
     • Participants could remember shorter words than longer words
     • Recall words that they articulate in about 2 seconds
     • Positive correlation between reading speed and memory span
   • Peterson and Peterson (1959)
     • After 18 seconds, fewer than 10 per cent of the trigrams were recalled correctly
   • Maintenance rehearsal affects duration of STM
   • Deliberate intention to recall affects duration of STM
   • Amount of information to be retained affects duration of STM

3. Encoding

   • A stimulus input can be encoded visually, acoustically or semantically
   • Conrad (1964) looked at whether people use acoustic coding in STM even when the information is presented visually
   • The sound of words affect encoding in STM
     • Conrad's study suggests that STM relies heaviy on acoustic coding
   • Other ways of encoding affect encoding in STM
     • Other modes of representation are possible
   • Baddeley (1966)
     • Acoustically similar words were much harder to recall in the correct order than words with dissimilar words
     • Similarity of meaning- slight detrimental effect