Coding and duration of the long term memory

Definitions of coding and duration?

-Coding: format which information is stored
• Duration: length of time info can be held in memory

Coding: Baddeley procedure

Participants were shown a list of words

asked to recall 20 mins later

words in the list were either acoustically similar, acoustically dissimilar, semantically similar or semantically dissimilar

Baddeley findings

Recall accuracy was worse on semantically similar words

LTM [long-term memory] codes information semantically

Duration Research: Bahrick procedure

• 392 participants aged 17-74 yrs
• Graduation class yearbooks of each participant were used
• There were 2 tests
• Photo recognition test – shown the yearbook photo of class members and asked to recall their name
• Free recall test – asked to recall names of graduating class without showing them a photo

Bahrick findings (photo recognition test)

• Photo recognition test:
• Those who graduated 15 years ago = 90% accuracy
• Those who graduated 48 years ago = 70% accuracy

Bahrick findings (free recall test)

• Free recall test:
• Those who graduated 15 years ago = 60% accuracy
• Those who graduated 48 years ago = 30% accuracy

Bahrick conclusion

• Conclusion: Duration of the LTM is unlimited

✅/❌ Bahrick – lab study

• Researcher has high control over variables in lab studies = high internal validity
• ❌COUNTERPOINT: No complete control over variables, as participants could have looked at the yearbook over the years, which improved their memory
• This is a cofounding variable – reduces the validity of the findings

✅ /❌ Bahrick – sample

• Sample used: wide range of ages + large sample size – this eliminates effects of anomalous results on the validity of findings.
• ❌ COUNTERPOINT: however all participants were from Ohio

✅ Bahrick – stimuli not artificial

• Stimuli: names of classmates
• Representative of one of most common memories we form in everyday lives
• High ecological validity

❌ Baddeley – artificial stimuli + information not stored for long enough to accurately represent ability to retrieve information from LTM

• List of words is not representative of memories we form = low ecological validity
• In real life information stays in our LTM for much longer than 20 mins before we need to recall them e.g., for exams – 20mins is not long enough to truly represent long term memory