Peterson and Peterson (1959) investigated short-term memory using trigrams, which are three-letter sequences such as CLS. Participants were asked to recall these trigrams after delays ranging from 3 to 18 seconds. The results showed that participants recalled approximately 80% of the trigrams after a 3-second delay, but this dropped to only 10% after an 18-second delay, leading the researchers to conclude that short-term memory decays within 18 seconds.

Peterson and Peterson's Study on Short-Term Memory Decay

A person is told a 4-digit code to enter a building. Immediately after hearing the code, they are unexpectedly engaged in a detailed 5-minute conversation with a friend. When they later try to enter the code, they find they cannot recall it. Using the principle that newly formed memories create a 'trace' that weakens over time if not actively maintained, explain this instance of forgetting.

Explaining an Instance of Forgetting

During memory trace decay, a memory trace becomes less activated as time passes, which ultimately results in the information being forgotten from short-term memory.

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The retention of information in short-term memory is influenced by two factors: memory trace decay and interference.

Factors Affecting Short-Term Memory Retention

Spielman, R. M., Jenkins, W. J., & Lovett, M. D. (2020, April 22). Psychology (2nd ed.). OpenStax. https://openstax.org/books/psychology-2e/pages/1-introduction

OpenStax Psychology (2nd ed.) Textbook

Memory Trace Decay

Proactive interference occurs when previously learned information interferes with the ability to learn new information. Keppel and Underwood (1962) demonstrated that proactive interference affects short-term memory retention by examining the initial trials of the trigram task.

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