Coding, Capacity and duration of memory Flashcards
What is coding?
Coding is the format in which information is stored in the memory system.
What is capacity?
Capacity is the amount of information that can be held in a memory store.
What is duration?
Duration is the length of time information can be held in memory.
Who did research on coding?
Baddeley
What was Baddley’s procedure?
-Alan Baddeley gave different lists of words to 4 groups to remember they were:
-acoustically similar
-acoustically dissimilar
-semantically similar
-semantically dissimilar
-Participants were shown their original words and they were asked to recall them in the right order.
What were Baddeley’s findings?
When participants were shown the words and had to recall them in the correct order immediately (STM recall) they tended to do worse with acoustically similar words. This shows that information in STM is coded acoustically. When the participants had to recall the words in the correct order after 20 minutes, they did worse with semantically similar words. This shows that information in LTM is coded semantically.
Eval- What does seperate memory stores do for Baddeley’s study?
-Identified a clear difference between two memory stores.
-Later research shows exceptions, but the idea that STM is mostly acoustic coding and LTM mostly semantic has stood the test of time.
-Important step in our understanding of the memory system, led to the creation of the multi-store model.
Eval- What does artificial stimuli do to Baddeley’s study?
-Used artificial stimuli instead of meaningful material.
-Had no personal meaning to the participants.
-May not tell us much about coding in different kind of memory tasks, especially everyday life.
-When processing more meaningful information, people may use semantic coding even for STM tasks.
-Suggests that findings from this study have limited application to memory in the real world.
Who did research on capacity (digit span)?
Joseph Jacobs (1887)
What was Jacob’s procedure?
To test someone’s digit span, the researcher gives, for example, 4 digits, and then the participant must recall these in the correct order out loud. If this is correct, the researcher then reads out 5 digits (these are random each time). When the participant can no longer recall the order correctly, this is their digit span.
What was Jacob’s findings?
-The mean span for digits across all participants was 9.3 items.
-The mean spean for letters was 7.3 items.
Eval- What does replication do to Jacob’s study?
-Has been replicated.
-Usually older study lack adequate control.
-For example, some participants digit spans might have been underestimated because they were distracted during testing (confounding variable).
-However, Jacob’s findings have been confirmed by other,better controlled studies since.
-This suggests that Jacob’s study is a valid test of digit span in STM.
Who did research on capacity (chunking)?
Miller (1956)
Describe the research done on capacity (chunking).
Miller (1956) made observations, for example, there are seven days in the week, and seven notes on the musical scale. Therefore, he said that the span (capacity) of STM is about 7 items +/-2. Miller noted that people can recall 5 words as well as they can 5 letters (do this by chunking- grouping units or chunks).
Eval- What does overestimation do to Miller’s research?
-Miller may have overestimated STM capacity.
-Cowan reviewed other research and concluded that the capacity of STM is only about 4 + /-1 chunks.
-Vogel et al conducted research on the capacity of STM for visual information and concluded that the capacity of STM for visual information is 4 chunks.
-Suggests that the lower end of Miller’s estimate (5 items) is more appropiate than 7 items.
Who did the research on the duration of STM?
Peterson and Peterson (1959)
What was Peterson and Peterson procedure?
Peterson and Peterson conducted their research on 24 undergraduate students. Each student took part in 8 trials. The students had to recall meaningless three-letter trigrams (for example THG) at different intervals (3, 6, 9, 12, 15, 18 seconds). To prevent rehearsal the students had to count backwards in threes or fours from a specific number, until they were asked to recall the letters.
What were Peterson and Peterson findings?
Peterson and Peterson found that the longer the interval, the less accurate the recall. At 3 seconds, around 80% of the trigrams were correctly recalled, whereas at 18 seconds only 10% were correctly recalled.
What did Peterson and Peterson conclude?
Peterson and Peterson concluded that STM has a limited duration of approximately 18 seconds. Furthermore, the results show that if we are unable to rehearse information, it will not be passed to LTM, providing further support for the MSM and the idea of discrete memory stores.
Eval- What does artificial stimuli do to Peterson and Peterson study?
-Recalling trigrams doesn’t reflect everyday memory activities where what we are trying to remember is meaningful.
-However, it could be argued that it isn’t completely irrelevant as we try to remember fairly meaningless material like phone numbers and postcodes.
-Lacks in external validity as it may not be possible to generalise the findings to real life.
Who did the research on the duration of LTM?
Bahrick et al (1975)
What was Bahrick et al procedure?
Bahrick et al conducted his research on 392 American graduates that were aged 17-74 on their memory of former classmates by asking them to match the names of former classmates with pictures from a year book photograph or getting them to free recall the names from 50 photographs.
What were Bahrick et al findings?
-Photo recognition within 15 years of graduation= 90% accurate.
-Photo recognition after 48 years of graduation= 70% accurate.
-Free recall after 15 years= 60% accurate.
-Free recall after 48 years= 30% accurate.
Eval- What does high external validity do to Bahrick’s study?
-Investigated meaningful memories (people’s names and faces).
-Other research has been conducted with meaningless pictures, recall rates were lower.
-This suggests that Bahrick et al’s findings reflect more ‘real’ estimate of the duration of LTM.
What is STM?
STM has a limited capacity store. Mainly coded acoustically. Average capacity of 5-9 items. Duration is between 18-30 seconds.
What is LTM?
LTM is a permanent memory store. Coding is meaning semantic. It has an unlimited capacity and can store memories for a lifetime.
