Short term & Long term

Memory

= term given to the structures & processes involved in the storage and subsequent retrieval of information

capacity

how much can be stored in memory

coding

how memory is stored

duration

how long the memory lasts before decaying/disappearing

key researchers

Miller

Jacobs

Peterson + Peterson

Baddeley

Bahrick

STM Capacity

1. Chunking - Miller, 1956

2. Magic Number - Miller, 1956

3. Numbers vs. Letters - Jacobs, 1887

1. Chunking

Miller, 1956

Research Details:

Traditionally used the serial digit span method where numbers or letters would have to be recalled in the correct order

- Listening to someone else's phone number and trying to learn it in 60 seconds

Research Conclusions:

Miller believed that our short-term memory stores "chunks" of info, rather than individual letters/numbers

- Chunking can increase capacity of info stored

2. Magic Number, capacity

Miller, 1956

Research details:

"Magic number seven plus/minus two"

- reviewed existing research into STM

Said we can hold "7 items" in STM, +/- 2

Research conclusions:

Most adults can store between 5 and 9 items in STM, the magic number = 7

He thought that STM could hold 7 (+/-2) as it only had a certain number of "slots" in which items could be stored

- presented the idea that short-term memory could only hold 5-9 chunks of information where a chunk is any meaningful unit

A03 - Miller, Capacity

P

= A weakness of Miller's theory (1956) is that, although it is supported by Jacobs' psychological research, it does not specify how large each "chunk" of information could be.

EX

= Due to this, we are unable to conclude the exact capacity of short-term memory.

EV

= Consequently, further research is required to determine each size of the information "chunks" so that we are able to understand the exact capacity of the short-term memory.

EXT

= In addition to this, Millers research into short term memory did not take into account other factors that affect capacity, such as how age may affect short term memory, and research by Cowen, 2001, found that the capacity of the short-term memory was more likely to be composed of 4 chunks as opposed to millers' suggestion of 5-9.

LB

= As a result of this, it can be argued that Miller overestimated the capacity of the STM and his theory lacks validity due to lack of specificity.

3. Numbers vs. Letters, capacity

Jacobs, 1887

Research details:

Digit span test

Sample of 443 female students (8-19) from North London Collegiate School

Repeat a string of numbers/letters in same order and the number/letter sequence gradually increased by adding another on

(Must be random, meaningless + show no pattern)

Number 7 and letter W weren't used as contain 2 syllables

Sequence was increased until participants could only recall the info on 50% of occasions

Research conclusions:

Jacobs found a difference between capacity for numbers and for letters

= he found out that people find it easier to recall numbers rather than letters

Average span for letters way 7.3 and for numbers it was 9.3

= so on average, participants could recall 9 numbers but only 7 letters

He also noticed that recall seemed to increase with age

= 8-year-olds being able to recall an average of 7 digits whereas 19 had an average of 9 digits

duration - Trigrams

Peterson and Peterson, 1959

Research details:

Husband & wife duo (Llyod & Margaret Peterson, 1959) aimed to test hypothesis that info which is not rehearsed is quickly lost from STM

Conducted lab experiment with a sample of 24 psychology students, had to recall meaningless 3-letter trigrams (THG, XHV) at different intervals (3, 6, 9, 12 seconds) Vowels avoided so words couldn't be constructed

Prevent rehearsal, students had to count backwards from specific number until asked to recall the letters (brown-Peterson technique)

Research conclusions:

Concluded that the STM had a limited duration, storage is very fragile + information can be lost with distraction or passage of time

Independent variable = the time interval between hearing experimenter say trigram + participant recalling trigram (after seeing a red light)

Dependent variable = number of trigrams correctly recalled by participants after every trial (6 trials in total)

Results showed that the longer each student had to count back, the less they were able to recall accurately

= after 3 secs, 80% recalled correctly

= after 6 secs, fell to 50%

= after 18 secs, less than 10% recalled correctly

Unable to rehearse info, won't be passed into LTM

STM duration= 18-30 seconds

A03 - P&P Strength

P

= However, a strength of this study is that it obtained objective, measurable results

EX

= Peterson and Peterson's study was highly controlled and took place in a laboratory of Indiana University, meaning they were able to have a high degree of control on extraneous variables

EV

= For example, Peterson and Peterson controlled the duration of time intervals, ensured that the trigrams were nonsense with no vowels used, and ensured that they didn't have acoustic similarities or semantic meaning

C

= However, the study could be deduced as being artificial as the patients were asked to memorise 3 letters trigrams. This is unlike anything they would have to memorise in their everyday live and due to this, we cannot apply these results to everyday examples of memories

LB

= On the other hand, the trigrams could be applied to memorising passcodes and bank pins, therefore reflecting day to day activities and the use of the scientific methods mean the procedure is easy to replicate and the results are valid

STM - Coding

Acoustically similar - Baddeley, 1960's

Acoustically Similar

Baddley, 1960's

Research Details:

= The way a memory is encoded describes the format that "raw" information is converted to when storing and retrieving "traces" of information

ACOUSTICALLY= SOUND

Participants are given 4 sets of words to recall

Set 1 = all sound similar

Set 2 = all sound different

Set 3 = all have similar meaning

Set 4 = all have different meaning

They have 60 seconds to recall the list

Research Conclusions:

Participants made significantly more mistakes on words that sounded alike (e.g., cat and cap)

= Similarly with letters, "s" and "x" would be confused, "p" + "n", etc.

Concluded that in STM, information is encoded by its sound so when we recall information from the STM, similar words get confused

= we remember things in the STM that sound different

Encoding acoustically = the dominant method of encoding info stored in STM

A03 - Baddeley

P

= A strength of Baddley's study is that it was a highly scientific experiment which obtained quantitative, reliable results and could be applied to real life situations

EX

= The study was a laboratory experiment which had tight controls and standardised procedures, meaning the study could be easily repeated. As well as this, objective data was collected, and the findings could be applied to daily situations as they explain why we are unable to do similar things at once

EV

= For example, not being able to have a conversation with a friend or family member whilst sending a text on your phone as this requires us to use both slave systems

C

= However, it can be argued that due to the laboratory settings and the artificial task, the study lacks ecological validity and mundane realism. In addition to this, the participants knew they were participating in the study and may have potentially guessed the aim, and therefore the study falls subject to demand characteristics

LB

= Despite this, the high degree of control over extraneous variables and the quantitative data obtained that is not open to interpretation bias provides evidence that this study has high scientific credibility which can explain daily memory

LTM - Capacity

LIMITLESS

n/a

Solso, 1991, compared LTM with large computers

Capacity = vast, theoretically, capacity of LTM could be unlimited and main constraint = accessibility, not availability

infinite, arguably immeasurable

LTM - Duration

Yearbook study - Bahrick et al., 1975

VLTM

Yearbook study

Bahrick et al., 1975

Research details:

investigated what they called VERY LTM (VLTM)

= free recall test where participants tried to remember the names of people in a graduate class

= a photo recognition test consisting of 50 pictures

Research Conclusions:

Free recall test...

-- tested after 15 years, recall = 60%

-- tested after 48 years, recall = 30%

Photo recall test...

-- after 15 years, recall = 90% accurate

--after 48 years, recall = 70% accurate

Recall can be accurate over a long period of time, leading to the term VLTM to describe the vastness of the LTM

A03 - Bahrick

P

= A strength of Bahrick et al.'s study is that it had high external validity

EX

= Bahrick's study used real-life meaningful memories which meant that experiment had higher ecological validity than other experiments, such as Miller's magic number study

EV

= By using a photo recall with the yearbook photos and a free recall test, he was not only able to test the long-term memories of the participants but also the very long-term memory (VLTM), using meaningful and significant recall tests which have accurate replication to everyday memory

EXT

= In addition to this, Bahrick used a large sample size and wide range of ages in his experiment meaning the findings of the study are easier to generalise to a wider population

LB

= Consequently, the study is recognised as highly significant in contributing to the study of everyday memory recall due to its real-life application and is recognised as a credible experiment

LTM - Coding

Semantically similar - Baddeley, 1960's

Semantically Similar

Baddeley, 1960's

SEMANTICALLY = MEANING

Research Details:

Participant given 4 sets of words to recall

Set 1 = all sound similar

Set 2 = all sound different

Set 3 = all have similar meaning

Set 4 = all have different meaning

60 seconds to recall list

Research Conclusions:

Patients were more likely to confuse words of similar meaning, replacing huge with vast, night + dark, etc.

Concluded that in LTM, info is encoded by its MEANING (semantically)