coding, capacity and duration

• Research on coding:

  baddeley (1966) gave different lists of words ro four groups of participants to remember

  • acoustically similar
  • acoustically dissimilar
  • semantically similar
  • semantically dissimilar

  participants were asked to recall a word list in the correct order, recalling from STM showed that acoustically similar words were recalled worse. when recalling from LTM, semantically similar words were recalled worse
• research on capacity:

  • jacobs (1887) found out by measuring digit span, that if you were to recall a list of words (4 words) you get them to recall it correctly. if done correctly, you then get them to recall a word list with 5 words and so on. The number of words that they can recall is their digit span - mean higher for digits than letters
  • Miller (1956) noted that things come in groups of seven (seven days a week, seven deadly sins) - thought the capacity of STM is 7+/-2

  chunking = grouping sets of digits or letters into chunks to help recalling
• research on duration:

  • Bahrick (1975) experimented by using high school year books; testing recalling by 1. photo recognition 2. free recall of all the names in graduating class

  participants tested within 15 years of graduating were 90% accurate in photo recognition, as the years increased the accuracy decreased - LTM may last up to a life time

  • Peterson and peterson (1959) gave students a consonant syllable and a 3 digit number, the student counted back from this number until told to stop to prevent mental rehearsal - STM is 18 seconds
• evaluation coding:

  strength:

  • identified a clear difference between two memory stores, STM uses acoustically and LTM uses semantically - led to MSM
  • lab experiment - highly controlled, make sure DV is affected by IV, valid findings

  weakness:

  • artificial stimuli, word lists had no relevance to every day life or personal meaning to the participants - limited application as when processing more meaningful information, people may use. semantic coding
• evaluation capacity:

  strength:

  • lab experiment, heavy control of extraneous variables - standardised so that it can be replicated easily.

  weakness:

  • lacks mundane realism - not an everyday activity - lacks ecological validity
  • overestimated STM capacity, Cowan (2001) reviewed other research and concluded that the capacity of STM is only 4+/-1
• evaluation duration:

  strength:

  • Bahricks study - high external validity, researchers investigated meaningful memories - more 'real' estimate of the duration of LTM
  • lab experiment - heavy control and no extraneous variables, easy to replicate

  weakness:

  • peterson and peterson - stimulus material was artificial, recalling consonant syllables does not reflect everyday memory - lacks external validity as its not applicable to remember meaningless information