Peterson and Peterson (Memory)
Peterson and Peterson (1959) Short-Term Retention of Individual Verbal Items (pg. 43-44) “Understand the aims, procedures and findings (results and conclusions), strengths and weaknesses of: Peterson and Peterson (1959) Short-term retention of individual verbal items”
Background to the study: The Petersons wanted to test the duration of the short-term memory store. The did this by preventing participants from rehearsing, by giving them an interference task: counting backwards in threes.
New term: A trigram is a set of three consonants, e.g. DVM.
Description: APRC
| A | • The Petersons aimed to test the duration of the short-term memory store. |
| P | • 24 Psychology students from an American University were used as participants in the study. • Each student was read a set of letters (a trigram: 3 consonants, e.g. FNL) to remember. • Then, they were read a three-digit number. The participant then had to count backwards from this number, in threes or fours. E.g. 709, 706, 703… to stop them rehearsing the trigram. This is called an interference task. • When signalled by a red light, the participant was asked to recall the trigram. This was after either 3, 6, 9, 12, 15 or 18 seconds of counting backwards. • Each participant had 8 goes at each time delay, meaning they did the procedure 48 times in total with different trigrams! |
| R | • When counting backwards for 3 seconds, 80% got the trigram correct. • When counting backwards for 18 seconds, less than 10% got the trigram correct. |
| C | • The short-term memory store has a short duration of about 18 seconds, without rehearsal. |
The Petersons did a second experiment, using 48 students from the same University. This time, half of the participants were allowed to repeat the trigram out loud, using vocal rehearsal. The other half of the participants had to stay in silence, so they could only rehearse the trigram in their head. They then had to do the counting backwards in threes task, as in the first experiment. Those given the chance to vocally rehearse the trigram were more likely to correctly recall the trigram, showing that rehearsal helps transfer information from the short term store to the long-term store.
Evaluation: GRAVE
| G | • They only used 24 students, therefore the results may not reflect other people’s memory. • Students should have good memory, whereas older adults may have a worse memory. |
| R | • The study had a standardised procedure (fixed timings for counting backwards) so the study can be repeated to check consistency. |
| A | • The study is useful as it supports multistore model of memory’s claim that the short term memory store has a short duration. • It shows us that we have to rehearse information if we want to remember it for longer than about 18 seconds. |
| V | • The results have low ecological validity, as it was an artificial memory test of trigrams. So it doesn’t reflect everyday memory recall of real events. |
| E | • There aren’t any ethical issues with the study as it was just a simple memory experiment, that didn’t cause any harm to participants. |
Peterson and Peterson (1959) Key Term Glossary
| Short term memory | Our temporary memory store (< 30 seconds, acoustic encoding, 5-9 chunks) |
| Duration | The amount of time information can be held in a memory store |
| Trigram | Three consonant letters, e.g. GKL |
| Rehearsal | Repeating information over and over again to help it store in the long term memory system (helps transfer from the STM to LTM) |
| Interference task | A task that interferes with your ability to rehearse information |
| Need more help? Want to stretch your understanding? |
| https://www.tutor2u.net/psychology/reference/duration-of-short-term-memory |
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