coding,capacity and duration

• coding is the process of converting information to another format to be stored in a memory store
• Baddeley gave participants lists of acoustically similar, dissimilar and semantically similar, dissimilar words to memorise and recall
• 1)immediate recall worse with acoustically similar words e.g. cat, rat. short term memory is coded acoustically
• 2)recall after 20 minutes of semantically similar words was worse e.g. big, large. long term memory is semantically coded
• strength of baddeley study is that it identified 2 memory stores, STM found to be mostly acoustic and LTM is mostly semantic, led to development of multi store model
• weakness of baddeley is that it used artificial stimuli, words had no meaning to the person so cannot account for everyday memory. processing more meaningful memory uses semantics including for STM. this means the study has limited applications
• capacity is the volume of information held in a memory store
• jacobs read list of digits to participants until they no longer could recall the order, the final digit is the digit span
• 1)on average, participants recalled 9.3 numbers and 7.3 letters in correct order immediately for jacob experiment
• miller observed everyday practise and found most items came in 7s. suggest capacity of STM is 7(plus or minus 2)but can be increased by chunking.
• chunking is putting sets of digits and letters into meaningful units
• weakness of jacob study is that is very old(1887), may have lacked control of variables such as concentration. Acts as a confounding variable lowering validity. however Jacobs study was replicated and his findings were confirmed in controlled setting
• weakness of miller is that it overestimates capacity of STM, Cowan reviewed research and concluded STM capacity is 4 (plus or minus 1) chunks. Miller lower end of 5 is more appropriate
• duration is the length of time information can be held in memory store
• Peterson and Peterson gave student pp constant syllables to memorise and 3-digit number to count down from to inhibit mental rehearsal of syllable. pp had to stop at retention intervals of 3,6,9,12,15,18 seconds each trial.
• 1)Peterson found 80% recall after 3 seconds and 3% after 18 seconds. STM duration without rehearsal is 18 seconds.
• Bahrick study for duration has 392 American participants complete recognition and free recall test
• In recognition test, 50 photos were shown from high school year books. 90% accurate answers after 15 years and 70% after 48 years.
• in free recall test, pp listed names from graduate class. 60% recall after 15 years and 30% after 40 years
• weakness of Peterson and Peterson is meaningless stimuli, recalling meaningless syllables does not account for everyday memory tasks, lacks external validity
• strength of Bahrick is high external validity, used meaningful stimuli of names and faces, lab studies with meaningless items had lower recall. Bahrick findings reflect real duration of LTM