Lesson 2 Coding, Capacity and Duration Flashcards
Sensory Register coding
Coding in the Sensory Register (SR) is modality specific. This means that each sensory store (e.g. iconic for visual information) codes information differently.
Baddeley (1966) Short Term Memory
Baddeley (1966) investigated coding in Short-Term Memory (STM); he gave participants four lists of words to recall. List A contained words that sounded similar and list B had words that sounded dissimilar. Lost C contained words that had similar meanings; list D had words with dissimilar meanings. Baddeley (1966) argued that STM is coded acoustically because when tested participants performed worse with list A than list B, but there was no difference between list C and D. Baddeley (1966) theorised that because STM organises information according to how it sounds, similar sounding words can become muddled.
Baddeley (1966) Long Term Memory
Baddeley (1966) repeated this experiment to test the coding of Long Term Memory (LTM). He tested participant’s recall of the lists after a 20 minute delay in order to ensure the information had passed into LTM. Participant’s recall of list C was worse than their recall of list D. There was no difference between list A and list B. Baddeley (1966) concluded that LTM is coded semantically. LTM organises information according to its meaning, so words with similar meaning can become confused.
Advantage and disadvantage of Baddeley
This study is a laboratory experiment and so it is easy to replicate as variables have been closely controlled. This means that reliability can be assessed.
The findings of this study have low ecological validity. The material (lists of unconnected words) which participants needed to recall was artificial (unlike the types of information which people need to recall in their everyday life) as was the laboratory setting.
Capacity of the SR
Unlimited
Jacobs (1887)
Jacobs (1887) used a digit span test to determine the capacity of STM. He gave participants several sequences of digits or letters, asking them to repeat each sequence immediately after he had given it, in the correct order. The sequences got longer by one item each time. Jacobs (1887) found that on average we can hold 9.3 digits and 7.3 letters. Miller (1956) reviewed psychological research studies and concluded that the span of STM is 7 (+/) 2. If we try to recall more information than we have the capacity for then new incoming information displaces old information. He also found that people can recall five words as easily as five letters, and so chunking (grouping large amounts of information into smaller groups) can help us remember more
Advantage and disadvantage of Jacobs (1887)
+ Jacob’s (1887) research was the first to acknowledge that STM capacity gradually improves with age.
- This study was conducted a long time ago, so may not have been done to the same scientifically rigorous standard as research today, therefore the validity of the findings is in question
Long Term Memory Capacity
Unlimited
Peterson and Peterson (1959) Short term Memory
Peterson & Peterson (1959) used nonsense trigram’s (random 3 consonants) to test STM duration. To prevent participants keeping the information in STM using maintenance rehearsal they were asked to count backwards from 100 in threes. After 3 seconds recall was accurate 90% of the time, after 9 seconds they were accurate 20% of the time, but after 18 seconds it was only accurate 2% of the time. They concluded that information in STM lasts for 18-30 seconds without rehearsal, before it is lost due to decay.
Advantages and Disadvantages of Peterson and Peterson (1959)
+ In this study, the researchers used fixed timings for participants to count backwards from. They also eliminated noise and other factors that could have had an influence on memory. The research can therefore be said to have a high level of control, using standardised procedures to make sure all participants experienced the same process
- The findings of this study may have been caused by interference rather than by STM having a short duration. It is possible that earlier learnt trigrams became confused with later ones.
Bahrick (1979) Long Term Memory
Bahrick (1979) tested 400 people of various ages (17-74) on their memory of their classmates. A photo recognition test consisted of participants being shown 50 photos and deciding if they belonged to their classmates or not. In a free recall test participants were asked to list the names they could remember from their graduating class. They found 90% accuracy at identifying faces of school friends within 15 years of leaving school. After 48 years this declined to 70%. Free recall of names of classmates was 60% accurate within 15 years of leaving school, dropping to 30% after 48 years. Bahrick et al. (1979) concluded that the duration of LTM is potentially a lifetime but sometimes we have retrieval failure and need retrieval cues in order to access this information.
Bahrick (1979) advantages and disadvantages
+ This study has higher ecological validity than Peterson and Peterson (1959) as the material used was more meaningful and relevant to everyday life.
- It is problematic to control for extraneous variables, such as people staying in touch after they left school or how many participants have looked in their yearbook since leaving school.
