IGCSE Psychology - Memory

Topic 02 - Memory

Peterson & Peterson (1959)

Aim : Peterson and Peterson first aimed to see if retention of items was affected by interference during recall intervals. In the second part of their study, they investigated whether silent or vocal rehearsal would affect recall of items.

Participants: Sample:

Experiment 1 - 24 students from an introductory psychology course at Indiana University, USA were selected. As part of their course, the students were required to take part in research experiments.

Experiment 2 – 48 students from the same university.

What they did: Standardised instructions given in both tasks. 2 test runs done.

Experiment 1 - Experimenter spells out a trigram followed by a number. Participants count backwards in 3’s and 4’s in time with a metronome to minimise rehearsal then recall the trigram. Each participant tested eight times at intervals: 3, 6, 9, 12, 15 and 18 seconds.

Experiment 2 - half the participants repeated a trigram aloud (‘vocal’ condition), half did not repeat the trigram but were given interval time before being asked to count backwards (‘silent’ group). Both groups tested after 3, 9 and 18 seconds.

Key Findings:

Experiment 1 - Results indicated that participants took an average of 2.83 seconds to begin their recall of the trigram once their counting had stopped. There was a significant difference between accurate recall following the first blocks (shorter interference intervals) than the last blocks (longer interference intervals). With a 3 second interference interval, participants could recall just over 50% of the trigrams accurately. This dropped to less than 10% from 15 seconds onwards.

Experiment 2 - Participant recall in the ‘vocal’ group improved with repetition, with longer repetition leading to more accurate recall. Participant recall in the ‘silent’ group did not improve with longer repetition.

Conclusion: They concluded that information decays rapidly from short-term memory with very little accuracy shown in recall in 15 second and 18 second trials and therefore, that short-term memory has limited duration. Overall conclusion - The rate of forgetting from short-term memory depends on the amount of rehearsal undertaken.

Barlett (1932)

Aim: To investigate whether the memory of a story is affected by previous knowledge. To find out if cultural background and unfamiliarity with a story would lead to distortion of memory when it was recalled. To test if memory is reconstructive and whether people store and retrieve information per expectations formed by cultural schemas.

Participants: Sample: 20 British participants (7 women, 13 men). The participants were not told the aim of the study; they believed they were being tested on the accuracy of recall.

What they did: Repeated reproduction was used. Each participant read a Native American story called ‘War of the Ghosts’ to themselves twice. The first reproduction happened 15 minutes later. There was no set interval beyond this and participants recalled the story at further intervals from 20 hours to almost 10 years.

Key Findings: Participants changed the story but preserved the order of events and main themes. 7 of the 20 participants omitted the title and 10 of the participants transformed the title – for example, ‘War- Ghost Story’. Other transformations included changing ‘canoes’ to ‘boats’ and changing the names of the characters.

Conlusion: They concluded that accuracy in reproduction of a story is an exception rather than a norm of memory. Omission of detail, simplification and transformation continues the more a story is repeated. There is a significant amount of interference with the story from reconstructing it. The details are altered to fit the participant’s own tendencies and interests. People tend to mostly use rationalisation reduces material to a form that was more common to the participant.