capacity, duration and encoding of memory

• Human memory can most broadly be defined as the process by which we retain information about events that happened in the past.
• Capacity is the amount of information that can be held in a memory.
• Jacobs' digit span technique (1887) found that participants could recall 9.3 digits or 7.3 letters.
• Miller 1956 - chunking found that when we chunk information it can improve the capacity of the Short term memory.
• Duration is the length of time information can be held in memory.
• Peterson and Peterson (1959) found that the duration of Short term memory without rehearsal is 3 seconds.
• Bahrick et al (1975) found that the duration of the Long term memory from 392 participants from Ohio, USA aged between 17 and 74.
• Braddeley's study of encoding (1966) used word lists to test the effect of the acoustic and sematic coding on Short term memory and Long term memory.
• Braddeley's study found that participants had difficulty remembering acoustically similar words in Long term memory but not Short term memory.
• Semantically similar words posed little problem for Long term memory but led to some muddles in Short term memory.
• Students are a specific type of population and their findings may not generalise to all populations.
• Another limitation of memory research is that they often use artificial tasks which may not be reflective of how we use our memory in everyday situations.
• Bahrick et al.'s research used real life meaningful memories (looking at the yearbook photos from their graduating class) which makes the findings more applicable to everyday memory tasks.
• The capacity of the Short term memory is not the same for everyone as demonstrated in a variation of the Jacobs' digit span technique where 8 year olds could recall 6.6 digits whereas 19 year olds could recall 8.6.
• Jacobs has not explained/accounted for the fact that different people have different capacity for memory.
• The findings that the capacity of the Short term memory is 7 +/- 2 cannot be generalised to everyone.
• One main limitation of memory research is that students are used as participants, which can limit the generalizability of the findings to other populations.
• Psychology students may have knowledge of research and may display demand characteristics by changing their behaviour to assist the experimenter, which can affect the validity of the study.
• Internal validity is lower in memory research due to the use of artificial tasks.
• Another limitation of memory research is the use of meaningless stimuli, which may not reflect how we use our memory in everyday situations.
• The findings from memory research may lack ecological validity and have limited application due to the lack of real-world relevance.
• Bahrick et al.'s research used real life meaningful memories, such as looking at the yearbook photos from their graduating class, making the findings more applicable to everyday memory tasks and more useful for generalization.
• The capacity of the Short term memory is another area of research with limitations, as it doesn't consider individual differences in that capacity is not the same for everyone.
• In a variation of the digit span technique, 8 year olds could recall 6.6 digits whereas 19 year olds could recall 8.6.
• Jacobs has not explained or accounted for the fact that different people have different capacity for memory, limiting the generalizability of the findings that the capacity of the Short term memory is 7 +/- 2.