Coding, capacity and duration

Define coding

The format in which information is stored in the various memory stores

What is the coding of the STM?

Information is coded acoustically

What is the coding of the LTM?

Information is coded semantically

What is the coding of the SR?

Coding is modality specific, meaning it depends on the sense

(e.g. visual information is coded into the iconic store whereas acoustic information is coded into the echoic store)

Define capacity

The amount of information that can be stored in the various memory stores

What is the capacity of the STM?

7±2 chunks of information

What is the capacity of the LTM?

Unlimited capacity

What is the capacity of the SR?

Unlimited capacity

Define duration

How much time information can be stored in the various memory stores

What is the duration of the STM?

18-30 seconds

(Although can be longer due to maintenance rehearsal)

What is the duration of the LTM?

Unlimited duration

(Can up to a lifetime)

What is the duration of the SR?

½ second

Give a study on coding

Baddeley (1966)

Outline the procedure of Baddeley’s study (1966)

Different lists of words were given to 4 groups of participants:

- Group 1 = acoustically similar

- Group 2 = acoustically different

- Group 3 = semantically similar

- Group 4 = semantically different 

Participants were asked to recall the words in order immediately and then after 20 minutes

What were the findings of Baddeley’s study (1966)?

Recall from STM was worse with acoustically similar words

Recall from LTM was worse with semantically similar words

Give a study on capacity

Jacob’s (1887)

Outline the procedure and findings of Jacob’s study (1887)

Researcher called out 4 digits and particpants recalled them aloud in order

If this was correct, the research called out 5 digits and so on until the participant could no longer recall correctly

This was repeated with letters

What were the findings of Jacob’s study (1887)

Mean digit span = 9.3

Mean letter span = 7.3

What did Miller observe about the capacity of STM?

People ‘chunk’ information together to improve the capacity of STM

The capacity of STM is 7±2 chunks of information

What are contradictory findings to Miller’s observation?

Cowan’s findings were that the capacity of STM is 4±1 chunks of information, suggesting Miller overestimated

Give a study for duration

Peterson and Peterson (1959)

Bahrick (1975)

Outline the procedure of Peterson and Peterson’s study (1959)

Each participant was given a trigram and a 3 digit number

The participants had to count down from the 3 digit number to prevent rehearsal of the trigram

On each trial, the participant had to recall the trigram after 3, 6, 9, 12, 15 or 18 seconds

What were the findings of Peterson and Peterson’s study (1959)?

Average recall after 3s = 80%

Average recall after 18s = 3%

Outline the procedure Bahrick’s study (1975)

392 participants aged between 17-74 were asked to recall members of their graduating class

They were also asked to complete a photo recognition test containing 50 photos from their high school yearbooks

What were the findings of Bahrick’s study (1975)?

Participants within 15 years of graduating were 60% accurate in free recall and 90% accurate in photo recognition

Participants within 48 years of graduating were 30% accurate in free recall and 70% accurate in photo recognition