Psychologists have conducted research that has found an important difference in the capacity of STM and LTM.
You need to be able to explain what capacity is: Find the key terms on p.7 Read: Capacity Use the information to answer the following question: Explain what is meant by capacity. (2 marks)
George Miller (1956) conducted a study to investigate the capacity of STM. Miller used the immediate digit span test to find out the capacity of STM. 1196661218180026601
Participants were read a series of numbers and repeated them back to the psychologist in the same order that they heard them. The number of digits they had to recall was increased until the participants were unable to recall them accurately. Miller found that the average digit span was 7 plus or minus 2 (the magic number 7).
Miller repeated this research using different stimuli (words, dots, musical tones) and concluded that the capacity of STM was limited to 5-9 items or ‘chunks’ of information.
Miller claimed that the capacity of STM could be increased by chunking. Individual digits or letters can be combined to form a single item or chunk of information, digits can be combined to form a telephone number, letters to form a word. The number of items that can be stored in STM remains limited but the amount of information stored in these chunks can be expanded.
Psychologists have been unable to establish the capacity of LTM. It is clear that LTM can store a huge amount of different kinds of information No limit to the amount of information that can be stored in LTM has been established.
Psychologists have conducted research that has found important differences in the way information is stored in STM and LTM. Find the key terms on p.7 Use the information to answer the following question: Explain what is meant by encoding. (2 marks)
When we see or hear something this information is briefly stored in sensory memory. It is stored in its original form, i.e. an image is briefly stored as an image.
Psychologists have tried to find out if this information has to be converted into a different code (recoded) before it can be processed by STM for transfer and storage in LTM.
One of the main ways that psychologists have tried to find out if information is recoded in STM is to conduct experiments that have looked at substitution errors. If people are briefly shown letters or words that look alike and then make mistakes when asked to recall the letters or words this suggests that STM uses a visual code. If people are read a list of letters or words that sound alike and then make mistakes when asked to recall the letters or words this suggests that STM uses an acoustic code.
Read the handout: ‘Encoding in STM’ What were the aims of the experiment? What were the main findings? What did the psychologists conclude?
Encoding in LTM Baddeley (1966) adapted Conrad’s study on encoding in STM and investigated the effects of acoustic and semantic similarity on STM and LTM recall. Link to research methods Turn to p. 76 - 77
Read p.76: ‘Baddeley’s study of STM encoding. Identify the IV. Identify the DV. Identify the design. What was the aim of the experiment?
How was the DV operationalised? Write a directional hypothesis for the experiment. Write a non-directional hypothesis for the experiment.
Do it yourself You are going to work in pairs to conduct your own study of encoding in STM and LTM. Read the do it yourself box