Peterson and Peterson (1959)

Aim: To investigate the duration of short-term memory, and provide empirical evidence for the multi-store model.

peterson and peterson

Procedure: A lab experiment was conducted in which 24 participants (psychology students) had to recall trigrams (meaningless three-consonant syllables, e.g. TGH).  To prevent rehearsal participants were asked to count backwards in threes or fours from a specified random number until they saw a red light appear. This is known as the brown peterson technique.

Participants were asked to recall trigrams after intervals of 3, 6, 9, 12, 15 or 18 seconds.

Findings: The longer the interval delay the less trigrams were recalled. Participants were able to recall 80% of trigrams after a 3 seconds delay. However, after 18 seconds less than 10% of trigrams were recalled correctly.

Conclusion: Short-term memory has a limited duration when rehearsal is prevented. It is thought that this information is lost from short-term memory from trace decay. The results of the study also show the short-term memory is different from long-term memory in terms of duration. Thus supporting the multi-store model of memory.

Criticisms: This experiment has low ecological validity as people do not try to recall trigrams in real life.


Peterson, L.R., & Peterson, M.J. (1959). Short-term retention of individual verbal items. Journal of Experimental Psychology, 58, 193-198

How to reference this article:

McLeod, S. A. (2008). Peterson and Peterson, 1959. Retrieved from

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