Jacobs 1887 Capacity of stm
Method: Participants presnted with a string of either letters or digits. they were then asked to repat the strings exactly. The no. of letter and digits in each string increased until the sequence failed to be recalled correctly.
Results: The majority of the time, ppts were only able to recall 9 digits and 7 letters. However this increased with age in childhood.
Conclusion: Jacobs' results suggested that stm has a limited storage capacity and can only hold up to betwen 5-9 items at a time. (Millers law). Individual differences were found, such as stm increasing with age. This could have been due to larger brain capacitty, or through the use of memory techniques thoughout adolecene development, such as chunking. Also, there were only a max of 10 digits in a sequence, where as there was a max of 26 letters.
Evalution: Jacobs research is artificial and lacks ecological validity. If the information presented to ppts had been more semantic, perhaps stm would have been shows to have an ever greater capacity. Also, previous sequences would have confused ppts for future sequences.