Coding, Capacity and Duration of Memory

Question 1

What is coding?

Answer 1

The format in which information is stored in memory

Question 2

How is STM coded?

Answer 2

Mainly acoustic (sound-based)

Question 3

How is LTM coded?

Answer 3

Mainly semantic (meaning-based)

Question 4

Baddeley (1966) - Coding in STM and LTM

Answer 4

Aim: To investigate the differences in encoding (coding) of information in STM and LTM
Procedure:
Participants were divided into four groups and given different types of word lists to remember:
1. Acoustically similar (e.g., cat, cab, can)
2. Acoustically dissimilar (e.g., pit, day, cow)
3. Semantically similar (e.g., big, large, huge)
4. Semantically dissimilar (e.g., good, hot, thin)
STM was tested by immediate recall; LTM was tested after a 20 -minute interval
Findings:
- STM: Participants struggled more with acoustically similar words than dissimilar ones
- LTM: Participants had more difficulty recalling semantically similar words.
Conclusion:
- STM primarily uses acoustic encoding
- LTM primarily uses semantic encoding

Question 5

Evaluation of Baddeley (1966) - Coding in STM and LTM

Answer 5

+ High control over variables
- Conflicting evidence - Visual encoding exists too
- Low ecological validity (artificial task)
- Small and unrepresentative sample

Question 6

Evaluation of Baddeley (1966, Coding) - + High control over variables

Answer 6

P: High control over variables (lab study)
E: The study was conducted in a tightly controlled laboratory environment, Word lists and recall intervals were standardised.
E: This increases internal validity, allowing researchers to confidently attribute recall differences to encoding type.

Question 7

Evaluation of Baddeley (1966, Coding) - - Conflicting evidence - Visual encoding exists too

Answer 7

P: Other studies challenge Baddeley’s claim that STM is coded acoustically.
E: Brandimonte & Frost (1995) found participants used visual encoding when verbal rehearsal was prevented.
E: Suggests STM may use multiple codes, undermining Baddeley’s strict acoustic vs semantic distinction and suggesting his model is overly simplistic.

Question 8

Evaluation of Baddeley (1966, Coding) - - Low ecological validity

Answer 8

P: Low ecological validity
E: The task used (memorising artificial word lists) lacks real-world meaning, In daily life, people remember names, stories, and personal events — not unrelated words.
E: This reduces external validity, as findings may not apply to everyday memory usage.

Question 9

Evaluation of Baddeley (1966, Coding) - - Small and unrepresentative sample

Answer 9

P: Small and unrepresentative sample
E: The study used a relatively small number of participants, Participant demographics (e.g., age, background) were not diverse or widely reported.
E: This limits the generalisability of the findings to the broader population, especially when considering individual differences in memory strategies.

Question 10

What is capacity?

Answer 10

The amount of information that can be held in memory

Question 11

What is the capacity of STM?

Answer 11

About 7 ± 2 items

Question 12

What is the capacity of LTM?

Answer 12

Unlimited

Question 13

What is the capacity of the Sensory Register?

Answer 13

Very large

Question 14

Miller (1956) – Capacity of STM

Answer 14

Aim: To investigate the capacity of short-term memory.
Procedure:
Miller reviewed existing research and observed that most people can remember around 7 items. He suggested this capacity can be increased by chunking, grouping items into larger, meaningful units (e.g., telephone numbers).
Findings:
Most people can hold 7 ± 2 items in STM.
Conclusion:
STM has a limited capacity of around 5 to 9 items. Chunking increases capacity by reducing the number of individual units stored.

Question 15

Evaluation of Miller (1956) – Capacity of STM

Answer 15

+ Simple, memorable finding (7 ± 2)
- Overestimates capacity
+ Influential theory

Question 16

Evaluation of Miller (1956, Capacity) - + + Simple, memorable finding (7 ± 2)

Answer 16

P: Simple, memorable finding (7 ± 2)
E: Miller’s chunking concept has become widely accepted and practical in learning contexts.
E: Good face validity and useful application.

Question 17

Evaluation of Miller (1956, Capacity) - – Overestimates capacity

Answer 17

P: Miller may have overestimated the capacity of STM by stating it holds 7±2 items.
E: Cowan (2001) reviewed research and found that the true STM capacity is closer to 4±1 chunks.
E: This challenges the accuracy of Miller’s estimate and suggests his theory may not be fully reliable, especially as chunk size and familiarity can vary between individuals.

Question 18

What is duration?

Answer 18

the length of time information can be held

Question 19

What is the duration of STM?

Answer 19

Around 18–30 seconds

Question 20

What is the duration of LTM?

Answer 20

Up to a lifetime

Question 21

What is the duration of the Sensory Register?

Answer 21

Very brief

Question 22

Peterson & Peterson (1959) - Study of Duration in STM

Answer 22

Aim: To investigate the duration of short-term memory (STM) — specifically, how long information remains in STM without rehearsal.
Procedure:
-Participants: 24 university students (psychology students from Indiana University).
-Task: Participants were given a trigram (a set of three consonants, e.g., “JTG”).
-They were also given a three-digit number (e.g., “326”) and told to count backwards in threes from it to prevent mental rehearsal.
-After intervals of 3, 6, 9, 12, 15 or 18 seconds, a cue was given, and participants were asked to recall the trigram.
-Each participant completed multiple trials using different time delays.
Findings:
-Recall accuracy decreased rapidly as the delay interval increased:
-3 seconds: ~80% correct recall
-6 seconds: ~60%
-9 seconds: ~40%
-12 seconds: ~20%
-18 seconds: <10%
-After 18 seconds, participants were almost unable to recall the trigram.
Conclusion: Short-term memory has a very limited duration — around 18–30 seconds when rehearsal is prevented.

Question 23

Evaluation of Peterson & Peterson?

Answer 23

• Sample bias
• Artificial task
  + High control
• Demand characteristic
  + Practical application

Question 24

Evaluation of Peterson & Peterson (Duration, 1959) - - Sample bias

Answer 24

P: The study’s sample was narrow and not representative of the general population.
E: All participants were psychology students, who may have higher memory skills or guessed the study’s purpose due to their academic background.
E: This limits the population validity of the study, as results may not generalise to other groups, such as children or older adults.

Question 25

Evaluation of Peterson & Peterson (Duration, 1959) - - Artificial task

Answer 25

P: The memory task used was artificial and lacks relevance to everyday memory. E: Participants had to recall meaningless trigrams (e.g., "XDF"), which is not reflective of how we use memory in real life (e.g., remembering names or appointments). E: This reduces ecological validity, as the findings might not generalise to everyday memory usage, limiting the external validity of the conclusions.

Question 26

Evaluation of Peterson & Peterson (Duration, 1959) - + High control

Answer 26

P: The study was a controlled lab experiment, which increases its scientific rigour. E: Researchers used standardised instructions, timing intervals, and controlled the environment, ensuring participants were treated the same. E: This means the study has high internal validity, and it can be replicated easily to test for consistency, which strengthens confidence in the findings.

Question 27

Evaluation of Peterson & Peterson (Duration, 1959) - - Demand characteristics

Answer 27

P: Participants were all psychology students, who may have guessed the purpose of the study. E: They may have altered their recall strategy or concentration. E: This could introduce participant bias, reducing validity and objectivity.

Question 28

Evaluation of Peterson & Peterson (Duration, 1959) - + Practical application

Answer 28

P: The finding that STM decays quickly unless rehearsed has real-world relevance E: In situations like remembering a phone number or short directions, rapid rehearsal is often needed. E: This supports the ecological relevance of their findings, even if the task itself was artificial.

Question 29

Bahrick et al. (1975) – Duration of Long-Term Memory

Answer 29

Aim: To investigate the duration of long-term memory, specifically examining how long people can remember information from their school years, such as the names and faces of classmates. Procedure: -Participants: 392 American participants aged between 17 and 74 years. -All had attended the same high school in Ohio. -Participants were tested using four memory tasks: -Free recall of names of people from their graduating class. -Photo recognition: identifying classmates from 50 yearbook photos. -Name recognition: matching names to yearbook photos. -Name and photo matching task. -Participants' results were compared to official high school yearbooks to assess accuracy. Findings: -Photo recognition (within 15 years of graduation): ~90% accurate. -Photo recognition (after 48 years): ~70% accurate. -Free recall (after 15 years): ~60% accurate. -Free recall (after 48 years): ~30% accurate. Conclusion: This supports the idea that LTM has a very long duration, potentially lifelong, particularly for certain types of information (e.g., meaningful personal memories).

Question 30

Evaluation of Bahrick et al. (1975) – Duration of Long-Term Memory

Answer 30

+ High ecological validity - Less control over extraneous variables + Large sample size with a wide age range - Free recall showed significant decline + Real-world application

Question 31

Evaluation of Bahrick et al. (1975, Duration) - + High ecological validity

Answer 31

P: The study used real-life, meaningful memories, like classmates’ names and faces. E: These are the kinds of things people naturally try to remember. E: This makes the findings highly generalisable to everyday memory, increasing external and ecological validity.

Question 32

Evaluation of Bahrick et al. (1975, Duration) - - Less control over extraneous variables

Answer 32

P: Unlike lab studies, the researchers had little control over participants' memory exposure. E: Some participants may have looked at their yearbook or stayed in touch with classmates. E: This may inflate memory performance, lowering internal validity and making it harder to determine the true duration of LTM.

Question 33

Evaluation of Bahrick et al. (1975, Duration) - + Large sample size with a wide age range

Answer 33

P: The study tested 392 people aged 17 to 74, enhancing generalisability E: It examined memory over a range of life stages, from recent to very remote recall. E: This increases the population validity and allows findings to be applied across different ages and time spans.

Question 34

Evaluation of Bahrick et al. (1975, Duration) - - Free recall showed significant decline

Answer 34

P: While recognition remained high, free recall declined significantly over time. E: Free recall dropped to 30% after 48 years. E: This suggests that while traces of memory remain, active retrieval becomes less reliable, showing limitations in LTM accessibility, not just availability.

Question 35

Evaluation of Bahrick et al. (1975, Duration) - + Real-world application

Answer 35

P: Understanding the duration of LTM has important uses in education, aging research, and memory rehabilitation. E: Shows that meaningful information can be retained for decades if appropriately cued. E: This supports cue-dependent retrieval and informs how older adults or those with memory loss might benefit from cues like images or context.