Coding, capacity and duration

Short-term memory (STM)

The limited capacity store.

Long-term memory (LTM)

The permanent capacity store.

Short-term memory (STM)

The limited capacity store.

Long-term memory (LTM)

The permanent capacity store.

Coding

The way in which information is stored in various memory stores.

Capacity

The amount of information that can be held in a memory store.

Duration

The length of time information can be stored in memory.

Baddeley (Coding in STM and LTM)

Baddeley wanted to test the forms in which memory is stored in both STM and LTM. He did this by showing participants four different lists of words:

1. acoustically similar

2. acoustically dissimilar

3. semantically similar

4. semantically dissimilar

What did the results show (coding)?

STM - Participants did worse with acoustically similar words - participants often got similar sounding words confused during recall so therefore the recall is the worst. Therefore, STM is coded acoustically.

LTM - Participants did worse with semantically similar words - often recalling a word with a similar meaning as they get them confused during recall.

What is the capacity of STM and LTM? How can it be extended?

The capacity of STM is 7+/-2.

The capacity of LTM is unlimited.

We can extended the capacity by chunking (when you link certain items together). You can recall 5 'chunks' of information.

Peterson and Peterson (Duration of STM)

The Peterson's tested undergraduate students. Each was given a consonant syllable (such as YCG) to remember and also given a number. The students were then asked to count backwards in 3s from this number until they were told to stop.

They found that our STM has a very short duration (as the time got longer the participants recall was shorter).

What's the duration of STM and LTM?

The duration of STM is around 18-30 seconds.

The duration of LTM is unlimited.

Bahrick (Duration of LTM)

Bahrick studied participants between the ages of 17 to 74 using yearbook pictures. The participants were tested through 2 ways:

1. Photo recognition - participants had to recall their names

2. Free recall - participants recalled the names of all the students in their class

What did the results show? (Bahrick's test)

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

Participants tested after 48 years were 70% accurate with photo recognition and 30% accurate with free recall.