Memory

Coding: Format in which info is stored in the memory.

-Acoustic coding: Remembering sound

-Semantic coding: Remembering the meaning.

Capacity: The amount of information tha can be held in a memory space.

Duration: Length of time we can hold information.

STM: about 18 seconds, capacity about 5-9. Usually acoustic coding.

LTM: unlimited capacity. Sematic coding usually.

Research on CODING:

Baddeley (1966)

Procedure: gave different list of words to four groups of participants to remember..

Group 1- acoustically similar. Cat..Sam..

Group 2-Bissimilar words. Pit, Few, Cow

Group 3- Similar, Great, Large..

Group 4- Dissimilar words, good, huge..

asked to recall in correct order.

STM recall: tended to do worse on acoustically similar, STM codes acoustically.

LTM recall ( 20 minutes later) did worse on semantically similar words. LTM codes semantically.

Jacobs (1887)

How much info can STM hold at any one time. What is its capacity? Technique to measure digit span.

Procedure:

4 digits to participant to repeat, then gives 5 and repeat.. etc.. until the participant cannot recall number of digits correctly. This determines individual digit span.

Findings:

Mean span of numbers recall was 9.3 items. For letters it was 7.3

Limitations:

It was done a while ago therefore confounding variables wouldnt have been controlled. Participants may have been distracted causing them to not perform as well as they might have however recent studys confirm the research, supporting its validity.

Miller (1956)

Notes that things come in 7's for example 7 notes on a musical scale, 7 days of the week, 7 deadly sins etc..

This suggests capacity of STM is about 7 (minus or plus 2)

Also noted that people can recall 5 letters aswell as 5 words they do this by chunking- grouping sets of digits or letters into units or chunks.

Limitation:
May have overestimated capacity of STM. Cowan (2001) reviewed other research and concluded that the much more likely capacity was only about four chunks. This means that Millers lower end estimate (5 items) was much more appropriate than 7 items.

Peterson & Peterson (1959)

24 undergraduate students.

each participant- 8 trials.

Each trial given a consonant syllable (trigram) and a 3 digit number.

then told to count back from the digit number until told to stop to prevent any mental rehearsal.

Each trial they were told to stop at different time. 3, 6, 9, 12, 15, 18... called an retention interval.

Findings:

STM has a very short duration about 18 seconds without verbal rehearsal.

Evaluation:

Stimulus material artifical. Doesnt relate to real life memory where what we are learning is meaningful. Lacks external validity.

However we do try to learn things slightly not meaningful like phone numbers so study isnt entirely irelevant.

Peterson & Peterson (1959)

24 undergraduate students.

each participant- 8 trials.

Each trial given a consonant syllable (trigram) and a 3 digit number.

then told to count back from the digit number until told to stop to prevent any mental rehearsal.

Each trial they were told to stop at different time. 3, 6, 9, 12, 15, 18... called an retention interval.

Findings:

STM has a very short duration about 18 seconds without verbal rehearsal.

Evaluation:

Stimulus material artifical. Doesnt relate to real life memory where what we are learning is meaningful. Lacks external validity.

However we do try to learn things slightly not meaningful like phone numbers so study isnt entirely irelevant.

Bahrick (1975)

Procedure:

392 participants from American state of Ohio, Aged between 17 - 74. High school year books obtained. Recall tested in various ways:

Photo recognition of 50 photos some from yearbook. free recall, participants recall all names from graduating class.

Findings:

Participants within 15 yrs of graduating got 90% on photo recognition.After 48 yrs recall declined 70% for photo recognition. Free recall was worse. 15 yrs was 60%  30% after 48 yrs.Shows LTM can last a long time.

Evaluation:

High external validity. Real life meaningful studies were used. Confounding variables not controlled therefore participants could may well of rehearsed their memories of year book for years.