Coding, Capacity and Duration Flashcards
What is coding in memory?
The process of converting information between different forms in memory.
Who conducted research on coding in memory?
Alan Baddeley (1966a, 1966b)
What were the four types of word lists used in Baddeley’s study?
• Acoustically similar (e.g., cat, cab, can)
• Acoustically dissimilar (e.g., pit, few, cow)
• Semantically similar (e.g., great, large, big)
• Semantically dissimilar (e.g., good, huge, hot)
What memory store did participants use when recalling words immediately?
Short-term memory (STM).
What type of words were more difficult to recall immediately (STM)?
Acoustically similar words.
What memory store did participants use when recalling words after 20 minutes?
Long-term memory (LTM).
What type of words were more difficult to recall after 20 minutes (LTM)?
Semantically similar words.
What do Baddeley’s findings suggest about coding in STM and LTM?
• STM is coded acoustically (sound-based).
• LTM is coded semantically (meaning-based).
Strength of CODING
One strength of Baddeley’s study is that it identified a clear difference between two memory stores.
Later research showed that there are some exceptions to Baddeley’s findings. But the idea that STM uses mostly acoustic coding and LTM mostly semantic has stood the test of time.
This was an important step in our understanding of the memory system, which led to the multi-store model
Limitation of CODING
One limitation of Baddeley’s study was that it used quite artificial stimuli rather than meaningful material.
For example, the word lists had no personal meaning to participants.
So Baddeley’s findings may not tell us much about coding in different kinds of memory tasks, especially in everyday life. When processing more meaningful information, people may use semantic coding even for STM tasks.
This suggests that the findings from this study have limited application.
What is digit span, and how is it measured?
Digit span is a measure of STM capacity. A researcher reads out a series of digits, increasing the number until the participant can no longer recall them correctly.
Who conducted research on digit span, and what did he find?
Joseph Jacobs (1887) found that the average digit span was 9.3 for numbers and 7.3 for letters.
What did George Miller (1956) propose about STM capacity?
He suggested that STM has a capacity of 7 ± 2 items.
What observations led Miller to his conclusion about STM capacity?
He noted that many things in daily life come in groups of seven (e.g., seven days of the week, seven musical notes, seven deadly sins).
What is chunking, and how does it help memory?
Chunking is grouping digits or letters into meaningful units, allowing more information to be stored in STM.
Strength of CAPACITY
One strength of Jacobs’ study is that it has been replicated.
The study is a very old one and early research in psychology often lacked adequate controls. For example, some participants’ digit spans might have been underestimated because they were distracted during testing (confounding variable). Despite this, Jacobs’ findings have been confirmed by other, better controlled studies since (e.g. Bopp and Verhaeghen 2005).
This suggests that Jacobs’ study is a valid test of digit span in STM.
Limitation of CAPACITY
One limitation of Miller’s research is that he may have overestimated
STM capacity.
Nelson Cowan (2001) reviewed other research and concluded that the capacity of STM is only about 4 (plus or minus 1) chunks.
This suggests that the lower end of Miller’s estimate (five items) is more appropriate than seven items.
Who studied the duration of short-term memory (STM), and how?
Peterson & Peterson (1959) tested 24 students by giving them consonant syllables (e.g., YCG) to remember while counting backward to prevent rehearsal.
What did Peterson & Peterson (1959) find about STM duration?
After 3 seconds, recall was about 80%, but after 18 seconds, it dropped to 3%. This suggests STM lasts about 18 seconds unless rehearsed.
Who studied the duration of long-term memory (LTM), and how?
Harry Bahrick et al. (1975) tested 392 people (aged 17–74) using high school yearbooks with photo recognition and free recall tests.
What were the key findings of Bahrick et al. (1975) about LTM?
• Photo recognition: 90% accuracy after 15 years, 70% after 48 years.
• Free recall: 60% accuracy after 15 years, 30% after 48 years.
What do Bahrick et al.’s findings suggest about LTM duration?
LTM can last a lifetime for some types of information, especially when recognition cues are present.
limitation of DURATION
One limitation of Peterson and Peterson’s study is that the stimulus material was artificial.
The study is not completely irrelevant because we do sometimes try to remember fairly meaningless material (e.g. phone numbers). Even so, recalling consonant syllables does not reflect most everyday memory activities where what we are trying to remember is meaningful.
This means the study lacked external validity.
Strength of DURATION
One strength of Bahrick et al’s study is that it has high external validity.
This is because the researchers investigated meaningful memories (i.e. of people’s names and faces). When studies on LTM were conducted with meaningless pictures to be remembered, recall rates were lower (e.g. Shepard 1967).
This suggests that Bahrick et al’s findings reflect a more ‘real’ estimate of the duration of LTM.
