Peterson and Peterson (1959) Short-term Retention of
Individual Verbal Items
Aims: (experiment 1) Aim: (experiment 2) Strengths:
To see if retention of items was affected by interference during recall intervals To see whether silent or vocal rehearsal would affect the recall of items The research has good control, using
standardised procedures to make
sure all participants experienced the
Procedure: (experiment 1) Procedure: (experiment 2) same process, meaning the study is
Sample: 24 students from an introductory psychology course at Indiana University, USA Sample: 48 students from the same university programme scientific because it can be
● As part of their course, the students were required to take part in research experiments In this procedure, half of the participants were instructed to repeat the replicated and the reliability of the
(opportunity/volunteer sampling) stimulus of a three-letter trigram aloud in time with a metronome, then findings can be checked to make
Each participant was given a standardised set of instructions which explained the process of the experiment stopped by an experimenter and instructed to count backwards from a sure they were not a one-off result
● This included explaining the ‘black box’ in front of them, and what to do at each of the light signals number (vocal condition) ● Researchers used fixed
○ The green light meant the trial was ready to begin The other half of participants were not instructed to repeat the stimulus timings for participants
○ The red light meant to stop counting and recall the trigram (three-letter consonant) trigram aloud, but they were given interval time before being asked to count to count backwards
Participants had two practice trials in order to ensure the instructions had been fully understood backwards from a number (silent condition) from, and also
At the beginning of each trial, the experimenter would spell out a trigram followed by a number from which the Both groups were tested on various rehearsal interval periods of eliminated noise and
participant had to count backwards in either 3’s or 4’s intermediate recall, 1 second and 3 seconds other factors that could
● In half of the trials the participants counted backwards in 3’s (e.g. 506, 503, 500 and so on) ● This was completed for three interference conditions of counting have had an influence
● In the other half they counted backwards in 4’s (e.g. 312, 308, 304, etc) backwards for 3 seconds, 9 seconds and 18 seconds on memory
Each participant was tested eight times at each of the following six recall intervals: 3 seconds, 6 seconds, 9 It has practical applications as it
seconds, 12 seconds, 15 seconds, and 18 seconds demonstrates how interference in
Results: (experiment 2) the form of verbal distractions can
Participant recall in the ‘vocal’ group improved with repetition, with longer affect our ability to retain
Results: (experiment 1) repetition leading to more accurate recall information
Results indicated that participants took an average of 2.83 seconds to begin their recall of the trigram once Participant recall in the ‘silent’ group did not improve with longer repetition
their counting had stopped Weaknesses:
There was a significant difference between accurate recall following the first block (shorter interference The procedure can be criticised
intervals) than the last blocks (longer interference intervals) Conclusion: (experiment 2) because trigrams are not a typical
With a 3 second interference interval, participants could recall just over 80% of the trigrams accurately Only in conditions where the repetition was vocal and controlled did use of our memory in everyday
● This dropped to less than 10% from 15 seconds onwards accuracy of recall improve situation
● Therefore the procedure
lacked mundane
Conclusion: (experiment 1) Conclusion overall: realism (a realistic
Information decays rapidly from short-term memory, with accurate recall of the trigrams decreasing rapidly The rate of forgetting from short-term memory depends on the amount of everyday task) as
over the duration of 18 seconds, and very little accuracy shown in recall in 15 second and 18 second trials (STM rehearsal undertaken people do not typically
limited duration) memorise trigrams
Individual Verbal Items
Aims: (experiment 1) Aim: (experiment 2) Strengths:
To see if retention of items was affected by interference during recall intervals To see whether silent or vocal rehearsal would affect the recall of items The research has good control, using
standardised procedures to make
sure all participants experienced the
Procedure: (experiment 1) Procedure: (experiment 2) same process, meaning the study is
Sample: 24 students from an introductory psychology course at Indiana University, USA Sample: 48 students from the same university programme scientific because it can be
● As part of their course, the students were required to take part in research experiments In this procedure, half of the participants were instructed to repeat the replicated and the reliability of the
(opportunity/volunteer sampling) stimulus of a three-letter trigram aloud in time with a metronome, then findings can be checked to make
Each participant was given a standardised set of instructions which explained the process of the experiment stopped by an experimenter and instructed to count backwards from a sure they were not a one-off result
● This included explaining the ‘black box’ in front of them, and what to do at each of the light signals number (vocal condition) ● Researchers used fixed
○ The green light meant the trial was ready to begin The other half of participants were not instructed to repeat the stimulus timings for participants
○ The red light meant to stop counting and recall the trigram (three-letter consonant) trigram aloud, but they were given interval time before being asked to count to count backwards
Participants had two practice trials in order to ensure the instructions had been fully understood backwards from a number (silent condition) from, and also
At the beginning of each trial, the experimenter would spell out a trigram followed by a number from which the Both groups were tested on various rehearsal interval periods of eliminated noise and
participant had to count backwards in either 3’s or 4’s intermediate recall, 1 second and 3 seconds other factors that could
● In half of the trials the participants counted backwards in 3’s (e.g. 506, 503, 500 and so on) ● This was completed for three interference conditions of counting have had an influence
● In the other half they counted backwards in 4’s (e.g. 312, 308, 304, etc) backwards for 3 seconds, 9 seconds and 18 seconds on memory
Each participant was tested eight times at each of the following six recall intervals: 3 seconds, 6 seconds, 9 It has practical applications as it
seconds, 12 seconds, 15 seconds, and 18 seconds demonstrates how interference in
Results: (experiment 2) the form of verbal distractions can
Participant recall in the ‘vocal’ group improved with repetition, with longer affect our ability to retain
Results: (experiment 1) repetition leading to more accurate recall information
Results indicated that participants took an average of 2.83 seconds to begin their recall of the trigram once Participant recall in the ‘silent’ group did not improve with longer repetition
their counting had stopped Weaknesses:
There was a significant difference between accurate recall following the first block (shorter interference The procedure can be criticised
intervals) than the last blocks (longer interference intervals) Conclusion: (experiment 2) because trigrams are not a typical
With a 3 second interference interval, participants could recall just over 80% of the trigrams accurately Only in conditions where the repetition was vocal and controlled did use of our memory in everyday
● This dropped to less than 10% from 15 seconds onwards accuracy of recall improve situation
● Therefore the procedure
lacked mundane
Conclusion: (experiment 1) Conclusion overall: realism (a realistic
Information decays rapidly from short-term memory, with accurate recall of the trigrams decreasing rapidly The rate of forgetting from short-term memory depends on the amount of everyday task) as
over the duration of 18 seconds, and very little accuracy shown in recall in 15 second and 18 second trials (STM rehearsal undertaken people do not typically
limited duration) memorise trigrams
