STM vs LTM: Duration Flashcards
Define duration
- The length of time information can be held in the memory.
Duration of STM: Research (pt.1)
Peterson + Peterson
- 24 undergraduate students.
- 8 trials per student.
- Given trigram (consonant syllable) e.g. YCG to remember + given a 3 digit number.
- They had to count backwards from the number until told to stop.
- This was to prevent any mental rehearsal taking place.
Duration of STM: Research (pt.2)
- On each trial they were told to stop after a certain period of time (e.g. 3, 6, 9, 12)- this is called the retention interval.
- This suggests that STM may have a very short duration unless verbal rehearsal takes place.
Duration of LTM: Research
Bahrick:
- Studied 392 ppts (17-74 years old).
- High school yearbooks were obtained from the ppts or from schools.
Recall was tested through:
1) Photo recognition test: 50 photos from the ppts high school yearbook.
2) Free recall test: ppts recalled the names of their graduating class.
Duration of LTM: Research (findings)
Photo recognition:
-Ppts who were tested within 15 years of graduation were 90% accurate in photo recognition.
- After 45 years recall declined to about 70% for photo recognition.
Free recall:
- After 15 years this was about 60% accurate, dropping to 30% after 48 years.
- This shows that LTM can last a very long time and supports the assumptions of the MSM.
Evaluation: Peterson & Peterson’s study
Limitation= the stimulus material was artificial.
- Trying to memorise the consonant syllables does not reflect everyday situations.
- The results may be exaggerated and not applicable to real life scenarios.
- This decreases the ecological validity of the study.
Evaluation: Bahrick’s study
Limitation= confounding variables are not controlled.
- E.g. Bahrick’s ppts may have looked at their yearbook photos over the years and rehearsed their memory.
- This makes the results less accurate + applicable to other scenarios.
- As a result both the scientific credibility of the study and the internal validity are decreased.
+= used meaningful info, leads to high mundane realism.
Strength of using lab research
High levels of control therefore, confounding/ extraneous variables are controlled.
- This decreases the likelihood of the results being influenced by external factors, therefore making them more reliable.
- This therefore means they are trusted more by other psychologists, and can be used as supporting evidence in other studies.
- This increases the value and internal validity of this research.
- Also makes it more scientific.
Weakness of using lab based research
It uses an artificial situation/ environment.
- It may produce results that are exaggerated, and that are not representative of everyday behaviours.
- Therefore they cannot be generalised to everyday situations.
- This decreases the ecological validity of the study.
