Coding, capacity, & duration of memory

What is encoding

The process of converting information between different forms

What is coding

The format information is stored in in the different memory stores

Who did research on coding

Alan Baddeley

What was Baddeleys research

He gave lists of words to 4 different groups and asked them to remember them

What did Baddeley find

• When they did it immediately and recalled the words from their STM they did worse with acoustically similar words (words that sound similar)

• When they recalled it after 20 minutes from their LTM they did worse with semantically similar words

What do Baddeleys findings show

That information is coded acoustically in the STM, and semantically in the LTM

Who investigated capacity

Joseph Jacobs (1887)

How did Jacobs investigate capacity

By measuring digit span

What did Jacobs find out

That the mean span for digits across all participants was 9.3 and the mean span for letters was 7.3

Who investigated chunking

George Miller (1956)

What did George Miller find

That things typically come in 7s and thought that the capacity of the STM was 7 plus or minus 2

Who investigated duration of the STM

Margaret and Lloyd Peterson (1959)

How did Margaret and Lloyd Peterson investigate duration of the STM

They tested 24 students in 8 trials each. On each trial the student was given a consonant syllable and a 3 digit number and told to count backwards from this number. On each trial they were told to stop after varying periods of time (3, 6, 9, 12, 18 seconds)

Why did the students have to count backwards

To prevent any mental rehearsal of the consonant syllable which would increase the duration of the STM

Why were the students told to stop after varying periods of time

To test the retention interval

What did they find

After 3 seconds average recall was around 80%, after 18 seconds about 3%

What does their research suggest

That the duration of the STM is about 18 seconds unless there is verbal rehearsal

Who investigated duration of the LTM

Harry Bahrick et al. (1975)

How did Bahrick investigate the duration of the LTM

He studied 392 American participants between the ages of 17 and 74. He got HS yearbooks for each of the participants. Recall was tested in 1 of 2 ways. 1) Photo recognition of 50 photos, 2) Free recall where they recalled all the names of their graduating class

What did Bahrick find

That participants tested within 15 years of graduation were about 90% accurate in photo recognition, but after 48 years it declined to about 70%. For free recall it was about 60% after 15 years and 30% after 48 years

What is a support evaluation point of coding

Baddeley’s study had a clear difference between the two memory stores. This was an important step in understanding of the memory system which led to the multi-store model

What is a limitation evaluation point of coding

It used artificial stimuli - the word lists had no personal meaning to participants so doesn’t tell us much about coding in memory tasks in everyday life. Findings have limited application

What is a support evaluation point for capacity

Jacob’s study has been replicated. Despite the study being very old, his findings have been confirmed by other better controlled studies. Suggests it is a valid test of digit span in STM

What is a limitation evaluation point for capacity

Miller may have overestimated STM capacity. Nelson Cowan reviewed other research and concluded the capacity of STM is only about 2 plus or minus 1.

What is a support evaluation point for duration

Bahrick’s study has high external validity because the researchers investigated meaningful memories. When studies were conducted with meaningless pictures, recall rates were lower

What is a limitation evaluation point for duration

Peterson and Peteron’s stimulus material was artificial. Recalling consonant syllables does not reflect most everyday memory activities. Lacked external validity