AO3

• Miller's (1956) theory is supported by psychological research. For example, Jacobs (1887) conducted an experiment using a digit span test, to examine the capacity of STM for numbers and letters. Jacobs used a sample of 443 female students (aged from 8-19) from the North London Collegiate School. Participants had to repeat back a string of numbers or letters in the same order and the number of digits/letters was gradually increased, until the participants could no longer recall the sequence.
• Jacobs found that the students had an average span of 7.3 letters and 9.3 words, which supports Miller's notion of 7+/-2.
• Although Miller's (1956) theory is support by psychological research, he did not specify how large each "chunk of information could be and therefore we are unable to conclude the exact capacity of STM.
• Consequently, further research is required to determine the size of information "chunks" to understand the exact capacity of STM.
• Finally, Miller's (1956) research into STM did not take into account other factors that affect capacity. For example, age could also affect STM and Jacobs' (1887) research acknowledged that STM gradually improved with age.