Duration:
Measure of how long info can be stored for
To keep info in STM for more than a few secs, what do humans do?
Rehearse the info
Which study supports the duration of STM?
Peterson and Peterson (1959)
Procedure of Peterson and Peterson (1959) study:
1) 24 undergrads presented w/ consonant trigram
2) Asked to count backwards in threes from random digit number to prevent rehearsal of trigram
3) After intervals of 3, 6, 9, 12, 15, 18 secs, participants had to repeat trigram
Results of Peterson and Peterson (1959) study:
Conclusion of Peterson and Peterson (1959) study:
Strengths and weaknesses of Peterson and Peterson (1959) study:
+ Variables are tightly controlled so study can be replicated
- Low ecological validity as trigrams are unrealistic (lacks mundane realism)
- Lacks pop validity (only undergrads)
- Was forgetting due to confusion from trigrams presented earlier (interference) or actual forgetting?
Which study supports the duration of LTM?
Bahrick et al (1975)
Procedure of Bahrick et al (1975) study:
Tested how well American pps between ages 17 and 74 could remember former classmates by identifying pics, matching names to pics and recalling names w/ no pic cue
Results of Bahrick et al (1975) study:
Even after 48 yrs:
- Linking names to pics –> 70% accuracy
- Free recall –> 30% accuracy
Conclusion of Bahrick et al (1975) study:
Strengths and weaknesses of Bahrick et al (1975) study:
+ High external validity as meaningful material was investigated
- Less control of IV as it is a natural experiment so there is a possibility names may have been rehearsed (confounding variable)
- Looks at very specific type of info (meaningful + regularly rehearsed)
In conclusion, what is the duration of STM and LTM?
Duration of STM: 18-30 secs
Duration of LTM: Lifetime
Which study supports the capacity of STM?
Jacobs (1887)
Procedure of Jacobs (1887) study:
Developed digit span technique
1) Researcher read out 4 digits and asked to repeat it back immediately
2) More digits added until pp could not repeat it accurately
Results of Jacobs (1887) study and reasoning:
Strengths and weaknesses of Jacobs (1887) study:
+ Has been repeated since w/ same results so it is valid
- Lacks ecological validity as repeating random lists of numbers is not realistic as more meaningful info may be recalled better
-Previous sequences recalled may have confused the pp
-Cannot be sure whether EVs were controlled as it was conducted long ago (lacks temporal validity)
Which study reviewed the capacity of STM and what did it conclude?
What is one evaluation of Miller’s (1956) study?
Coding:
Form in which info can be stored in the various memories
What are the 3 ways of coding?
Which study supports the coding of STM and LTM?
Baddeley (1966)
Procedure of Baddeley (1966) study:
Participant shown sequence of 5 words under these 4 conditions + immediately/after 20 mins write them down in order
1) Acoustically similar
2) Acoustically dissimilar
3) Semantically similar
4) Semantically dissimilar
Results of Baddeley (1966) study: