Coding, capacity, duration research

Question 1

What is STM?

Answer 1

memory for events in the present or immediate past

Question 2

What is LTM?

Answer 2

memory for events in the more distant past

Question 3

Who researched into the capacity of STM?

Answer 3

Jacobs (1887)

Question 4

What is the research into the capacity of STM?

Answer 4

The digit span technique
The researcher gives 4 digits to the participant and the participant is asked to recall these in the correct order out loud. If this is correct the researcher reads out 5 digits and so on until the participant cannot recall the order correctly. This determines the individual’s digit span. He found that the average span for digits was 9.3 items and 7.3 for letters.

Question 5

Why is it easier to recall digits instead of letters?

Answer 5

There are 10 digits, but 26 letters

Question 6

What is the capacity of STM?

Answer 6

7 items +or- 2

Question 7

Who discovered the capacity of STM?

Answer 7

Miller (1956)

Question 8

What was Miller’s research into STM?

Answer 8

Miller (1956) observed that things in everyday practice come in sevens: 7 notes on the musical scale, 7 days of the week, 7 deadly sins, etc. Miller therefore thought the capacity of STM is 7 items, plus or minus 2. Miller (1956) also found that people can recall 5 words as well as they can recall 5 letters. They do this by chunking – grouping sets of digits or letters into units or chunks.

Question 9

What is the capacity of LTM?

Answer 9

can approach infinity

Question 10

Evaluation into research on capacity of STM - Jacobs strength

Answer 10

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, a confounding variable. Despite this, Jacobs’ findings have been confirmed by other better controlled studies since conducted in 2005 that are high in internal validity. This suggests that Jacobs’ study is a valid test of digit span in STM.

Question 11

Evaluation research into capacity - ecological validity

Answer 11

One limitation is that research into the capacity of STM is low in ecological validity. Many of the studies into STM, such as Jacobs’ digit span task, uses tasks that would never be replicated in a real-world situation and therefore reduces the usefulness of the experiment. Additionally, Jacobs’ experiment was conducted in a lab, being an artificial setting, with controlled settings, another aspect that further decreases the ecological validity of the research as people very rarely find themselves in lab settings. This is a limitation as it means the results concluded from these studies are likely to not be generalisable due to them lacking real-world application value.

Question 12

Evaluation of research into STM - Miller

Answer 12

One limitation of Miller’s research is that he may have overestimated STM capacity. A psychologist reviewed other research into STM 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.

Question 13

Who conducted research into the duration of STM?

Answer 13

Peterson and Peterson (1959)

Question 14

What is the research into the duration of STM?

Answer 14

• Tested 24 undergraduate students.
• Participants were presented with a 3 letter consonant nonsense syllable (trigram) followed by a 3 digit number.
• Participants were then asked to count backwards in 3’s to prevent them from rehearsing the trigram.
• On each trial the time spent counting backwards was different (3, 6, 9, 12, 15, 18 seconds). This is called the retention interval.

Question 15

What are the findings of research into duration of STM?

Answer 15

Participants remembered 80% when there was a 3 second interval, but only 3% when there was an 18 second interval.
Short term memories last for a very short period of time, unless they are rehearsed or paid attention to. Therefore STM is limited in duration - less than 18 seconds as long as rehearsal is prevented.
Rehearsal is a way of transferring information into LTM, e.g. by repeating it over and over again or by attending to it!

Question 16

Who researched into the duration of LTM?

Answer 16

Bahrick et al.

Question 17

Procedures of research into duration of LTM

Answer 17

• Studied 392 American participants aged 17-74
• Using the participants high school yearbooks he tested recall by:
• Photo recognition test consisting of 50 photos, some from their yearbooks, some random (say whether they went to school or not)
• Free recall test – participants recalled all names of their graduating class

Question 18

Results of research into duration of LTM

Answer 18

PHOTO RECOGNITION RESULTS
* Participants who tested within 15 years of graduation were about 90% accurate
* After 48 years, recall declined to about 70%

FREE RECALL RESULTS
* About 60% after 15 years
* 30% after 48 years

Question 19

Evaluation of research into duration of STM

Answer 19

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, such as phone numbers. Even so, recalling consonant syllable does not reflect most everyday memory activities where what we are trying to remember is meaningful. This means the study lacked external validity.

Question 20

Evaluation of research into duration of LTM

Answer 20

One strength of Bahrick et al’s. study is that it has high external validity. This is because the researchers investigated meaningful memories, people’s names and faces. When studies on LTM were conducted with meaningless pictures to be remembered, recall rates were lower. This suggests that Bahrick et al’s. findings reflect a more ‘real’ estimate of the duration of LTM.

Question 21

Evaluation of research into duration of LTM counterpoint

Answer 21

However, Bahrick et al’s. study faces many problems concerning confounding variables. For example, some people may have a larger class than others, some people join high schools later than others, some people may have never looked at the book since and others may look at it regularly. This suggests this study is low in internal validity as it has a lack of control over variables which would have had a great impact on results

Question 22

Who conducted research into coding?

Answer 22

Baddeley

Question 23

Procedures for research into coding

Answer 23

Baddeley (1966) – gave different lists of words to four groups of participants to remember:
* Group 1 (acoustically similar): words sounded similar (e.g. cat, cab, can).
* Group 2 (acoustically dissimilar): words sounded different (e.g. pit, few, cow).
* Group 3 (semantically similar): words with similar meanings (e.g. great, large, big).
* Group 4 (semantically dissimilar): words that all had different meanings (e.g. good, huge, hot).

Question 24

Findings of research into coding

Answer 24

When participants were asked to recall the words in the correct order immediately after hearing them (STM recall), they tended to do worse with acoustically similar words.
If participants were asked to recall the word list after a time interval of 20 minutes (LTM recall), they did worse with the semantically similar words.
This suggests that STM is largely encoded acoustically whereas LTM is largely encoded semantically.

Question 25

Evaluation of research into coding - strength

Answer 25

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. However 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.

Question 26

Evaluation into research of coding - limitation

Answer 26

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.

Question 27

What is capacity?

Answer 27

how much data can be held in a memory store

Question 28

What is duration?

Answer 28

the length of time information can be held in memory

Question 29

What is coding?

Answer 29

Once information gets into the memory system, it is stored in different formats, depending on the memory store. The process of converting information from one form to another is called coding.