short and long term memory

Question 1

research on coding

Answer 1

• Baddeley (1966a/b) gave 4 different types of word lists to pps: semantically similar/dissimilar; acoustically similar/dissimilar
• when pps used their STM they tended to do better with words that sounded acoustically similar
• when pps used their LTM they tended to do better with words that sounded semantically similar
• this suggests that words are encoded in the STM acoustically and encoded in the LTM semantically

Question 2

research on capacity

Answer 2

• J. Jacobs (1997) asked pps to recall digit or letters - serial digit span. he also used a metronome so that the investigator said a sound every half second = STM.
• he found that the average score was 9.3 for digits and 7.3 for letters
• he also found that a person’s digit span increased with age - 8 year old’s = average of 6.6 digits compared to 19 year old = 8.6 digits.
• shows that STM has a limited capacity of 5-9 items and is not fixed so individual differences may play a role.

Question 3

research to support Jacob’s research on capacity

Answer 3

• George Milner (1956) made observations of everyday practice. e.g. he notes that things come in severs and found that if we chunk information together so that it has some form of meaning we can increase the capacity of STM.
• he devised the number 7+/-2 which supports Jacobs findings - suggest that the span of STM is limited to 5-9 items.
• however, Milner also notes that people can remember 5 words just as well as they can recall 5 letters as they do this by chunking - grouping sets of digits or letters into units or chunks.

Question 4

research on duration - STM

Answer 4

• Peterson and Peterson’s (1959) tested 24 undergraduate students and each student took part in 8 real trials and 2 practice trials.
• gave students a trigram and also a 3 digit number. students were then asked to count backwards from that 3-digit number until told to stop - prevent any mental rehearsal of the trigram.
• there were retention intervals:3,6,9,12,15, and 18 seconds.
• accuracy of pps was on average: 90% for 3 seconds, 20% for 9 seconds and 2% for 18 seconds.
• suggests that STM has a very short duration unless we repeat something over and over (rehearsal)

Question 5

research on duration - LTM

Answer 5

• Bahrick et al (1975) studied 392 pps aged between 17 and 74. their high school yearbooks were obtained and recall was tested by: photo recognition consisting of 50 photos, and free recall where pps recalled all the names of their graduating class.
• pps who were tested within 15 years of graduation were about 90% accurate in identify faces, and after 48 years, this declined to about 70% for photo recognition. free recall, was about 60% accurate after 15 years, dropping to 30% accuracy after 48 years.
• suggests that out mind can store an infinite amount of information, but we sometimes need a retrieval cue to help us remember as we cannot always access the information

Question 6

AO3: artificial stimuli

Answer 6

one limitation is that their studies used artificial stimuli rather than meaningful material. for example in Petersons’ they got pps to memorise a trigram. this does not truly reflect most everyday memory activities where what we are trying to remember is meaningful. however, we do try to remember meaningless things e.g. groups of numbers (pjone number) and letters (postcode). this means that although the tasks were artificial, their studies do have some relevance to everyday life

Question 7

AO3: higher external validity

Answer 7

one strength of Bahrick et al’s study is that it has a higher external validity. real life meaningful memories were studied. when studies on LTM have been conducted with meaningless pictures to be remembered, the recall rates were lower. however a limitation is that confounding variables were not controlled. for example, pps may have looked at their yearbook photoes and rehearsed their memory over the years, or still could be friends with their graduating year.

Question 8

AO3: not so many chunks

Answer 8

Milner may have overestimated the capacity of STM. Cowan (2001) reviewed other research conducted that the capacity of STM is only about 4 +/-1 chunks.
research on the capacity of STM for visual information also found that 4 times was about the limit (Vogel et al, 2001). this means that the lower end of Milner’s range is more accurate and suggests that STM may not be an extensive as was thought

Question 9

AO3: Jacob’s study limitation

Answer 9

one limitation of Jacob’s study is that it was conducted a long time ago. early research into psychology often lacked adequate control e.g. some pps may have been distracted while they were being tested so they didn’t perform as well as they might. this would mean that the results may not be valid because they were confounding variables that were not controlled.
however the results of this study have been confirmed in other research supporting its validity