Jacobs (1887) The Capacity of the STM

Question 1

Method

Answer 1

• Participants presented with a string of letters/digits,
• Had to repeat them back in the same order,
• Number of digits or letters increased until the participants failed to recall the sequence correctly.

Question 2

Results

Answer 2

• Majority of the time, participants recalled about 9 digits and about 7 letters,
• Capacity increased with age during childhood.

Question 3

Conclusion

Answer 3

• Based on the range of results, Jacobs concluded that STM has a limited storage capacity of about 5-9 items,
• Individual differences were found, such as STM increasing with age in childhood, possibly due to use of memory techniques such as chunking,
• Digits may have been easier to recall as there were only 10 different digits to remember, compared to 26 letters.

Question 4

Evaluation

Answer 4

• Research is artifical and lacks ecological validity,
• Meaningful info may be recalled better, perhaps showing STM to have an even greater capacity,
• Previous sequences recalled by participants might have confused them on future trials.