1. Duration – STM & LTM Clearly, LTM can store information for a much longer time than LTM Some researchers have tried to measure their durations exactly: Peterson & Peterson (1959) – STM Peterson & Peterson (1959) – STM Bahrick et al (1975) – LTM Bahrick et al (1975) – LTM These are key studies so make sure you learn APFCC www.psychlotron.org.uk

2. Duration – STM Peterson & Peterson (1959) PPs presented with ‘trigrams’ (CVC nonsense syllables) and asked to recall them (accurately & in order) Between exposure & recall there was a delay in which they did an interference task Between exposure & recall there was a delay in which they did an interference task The length of the delay was varied The length of the delay was varied Results obtained by plotting recall against length of delay www.psychlotron.org.uk

3. Duration - STM 369121518 % recall Length of delay (s) www.psychlotron.org.uk

4. Duration - STM Recall declined steadily with time After 3s 80% correct After 3s 80% correct After 6s less than 50% After 6s less than 50% After 18s less than 10% After 18s less than 10% Information is lost rapidly from STM, which seems to have a duration of about 20s if nothing is done to maintain the info (i.e. rehearsal) www.psychlotron.org.uk

5. Duration - STM The experiment lacked realism Nonsense trigrams were used to eliminate the effect of meaningfulness Nonsense trigrams were used to eliminate the effect of meaningfulness However, this is unlike the info that people typically deal with However, this is unlike the info that people typically deal with The use of interference task is a problem We cannot tell if the info decayed (as the Petersons claim) or was displaced by the task We cannot tell if the info decayed (as the Petersons claim) or was displaced by the task www.psychlotron.org.uk

6. Duration - LTM Bahrick et al (1975) Test of VLTM using naturalistic materials 392 US PPs who had left high school 1-48 years previously tested for recall of classmates Free recall Free recall Recognition of photos Recognition of photos Name recognition & photo matching Name recognition & photo matching www.psychlotron.org.uk

7. Duration - LTM % recall Years since leaving High School Picture recognition Name recognition Free recall www.psychlotron.org.uk

8. Duration - LTM Recall was remarkably high 80% accuracy for name recognition at 48yrs 80% accuracy for name recognition at 48yrs 30% accuracy for free recall at 30yrs 30% accuracy for free recall at 30yrs Supports the idea that LTM can store some types of info for very long time Free recall becomes more difficult over time, but recognition does not diminish much Free recall becomes more difficult over time, but recognition does not diminish much www.psychlotron.org.uk

9. Duration - LTM Ecological validity was high The study used a naturally occurring form of info so avoided the artificiality often present in memory studies The study used a naturally occurring form of info so avoided the artificiality often present in memory studies The type of info used was very specific Classmates may have high emotional significance, and there is usually great opportunity for rehearsal Classmates may have high emotional significance, and there is usually great opportunity for rehearsal Conclusions not generalisable to other types of information Conclusions not generalisable to other types of information www.psychlotron.org.uk