Outline and evaluate research into duration in memory. [8 marks]

ESSAY HINT: For questions like this, students may choose to focus on research studies or theories. When using studies, they must provide precise details of the methodology and findings. Evaluation must also be applied directly to the studies discussed; students should avoid generic points and explain specifically, for example, how the use of an artificial task affects a particular study’s ecological validity.

Peterson and Peterson investigated the duration of short-term memory (STM) using a repeated measures design involving 24 students. Participants were given a three-letter consonant trigram, such as “CHJ”, followed by a three-digit number. To prevent rehearsal, they counted backwards in threes or fours from this number. After an interval of 3, 6, 9, 12, 15 or 18 seconds, a red light signalled that participants should recall the trigram. Recall became progressively poorer as the interval increased: more than 50% of the trigrams were recalled correctly after 3 seconds, compared with fewer than 10% after 18 seconds. Peterson and Peterson concluded that information remains in STM for approximately 18 seconds when rehearsal is prevented.

One strength of Peterson and Peterson’s research was the high level of control. The researchers used standardised trigrams, retention intervals, and counting tasks, ensuring that each participant completed the study under similar conditions. The counting task also prevented rehearsal, ensuring that participants could not deliberately retain the trigrams in STM. This reduced the influence of extraneous variables and increased confidence that the retention interval caused the decline in recall. Furthermore, the standardised procedure makes the study easy to replicate. If similar findings are obtained, this would demonstrate that its conclusions about the duration of STM are reliable.

However, Peterson and Peterson used an artificial memory task. Remembering meaningless consonant trigrams while counting backwards does not reflect how people typically use memory in everyday life, where information is generally meaningful and connected to existing knowledge. Participants may therefore have found the trigrams particularly difficult to remember and behaved differently from how they would in natural settings. Consequently, the study may underestimate the duration of STM for meaningful information, limiting the ecological validity and everyday application of its findings.