Coding, capacity and duration

What is meant by 'coding' in memory?

The format in which information is stored in memory (e.g., acoustic, semantic).

What was the method of Baddeley's (1966) study on coding?

Participants were given word lists that were either acoustically similar/dissimilar or semantically similar/dissimilar. They recalled them immediately (testing STM) or after 20 minutes (testing LTM).

Result: Immediate recall (STM) was worse for acoustically similar words. Delayed recall (LTM) was worse for semantically similar words.

Conclusion: STM codes acoustically, LTM codes semantically.

What is a limitation of Baddeley's study on coding?

It used artificial stimuli (meaningless word lists), which may not reflect how we code meaningful information in everyday

What was the method of Jacobs' (1887) study on STM capacity?

The researcher read out a sequence of digits or letters, and the participant had to recall them in order. The number of items was increased until the participant failed.

Result: The mean span was 9.3 digits and 7.3 letters.

Conclusion: This helped establish the capacity of STM as being limited.

What was Miller's (1956) contribution to understanding STM capacity?

He reviewed previous research and made observations of everyday life.

Result/Conclusion: He proposed that the capacity of STM is 7 ± 2 items, but that we can increase this by grouping items into chunks (chunking).

What is a more modern view on STM capacity?

Cowan (2001) reviewed research and suggested a lower capacity of around 4 ± 1 chunks.

What was the method of Peterson and Peterson's (1959) study on STM duration?

Participants were given a consonant trigram (e.g., YCG) and then a 3-digit number. To prevent rehearsal, they counted backwards from the number for different retention intervals (3-18 seconds) before recalling the trigram.

Result: Recall declined rapidly. After 3 seconds it was ~80%; after 18 seconds it was ~3%.

Conclusion: The duration of STM is about 18-30 seconds without rehearsal.

What was a limitation of the Peterson and Peterson study?

It used artificial, meaningless stimuli (consonant syllables), which lacks external validity for everyday memory.

What was the method of Bahrick et al.'s (1975) study on LTM duration?

392 participants of various ages were tested on their memory for high school classmates using photo-recognition and free recall tests.

Result: Photo recognition was about 90% after 15 years and 70% after 48 years. Free recall was less accurate.

Conclusion: LTM for meaningful information can last a lifetime.

What is a strength of Bahrick's study on LTM duration?

It has high external validity because it investigated meaningful, real-world memories (faces and names).