Memory

LTM and STM

The format of stored information

Duration- length of time information can be storedCapacity- amount of information which can be stored

A memory store which is

1. Limited in capacity to an average of 5-9 items
2. Limited in duration to 18-19 secs
3. Coded acoustically

A memory store which is

1. Permanent
2. Theoretically unlimited in capacity. Can store memories for up to a life time.
3. Coded semantically.

Acoustic coding is where information is coded according to sound where semantic coding is coding according to meaning.

BaddeleyA: To determine the format of information coding in the STM and LTM. P: Independent measures procedure 4 groups were provided with lists of words which were either acoustically or semantically similar or dissimilar- which they were asked to recall. F: Where participants were asked to recall the words immediately, they did worse with acoustically similar words and where asked to recall words 20 minutes later they did worse with semantically similar words. C: Information in the STM is coded acoustically. Information in the LTM is coded semantically.

Digit span and chunking

JacobsA: To assess the capacity of the STM by how many digits can be remembered by the participant. P: The researcher lists a number of digits and the participant must recall the digits verbally. The researcher continues to repeat this process, adding another digit each time, until the participant can no longer recall the digits accurately. This determines the digit span. F: 9.3 digits were recalled on average.(extra~ When repeated with letters 7.3 was average).(simplify~ STM average capacity is 7-9 items)

MillerSupports Jacobs- 9.3 digits/7.3 lettersF: Miller observed that in every day life items are often grouped in 7s (eg- deadly sins, days of the week) and suggested that the STM capacity is therefore 7 items +/- 2 items. He also noted that people are capable of recalling 5 words as efficiently as they can 5 letters. Chunking aids more information storage in the STM.

Peterson A: To assess the duration of the STM through prevention of rehearsal, so that information may not be committed to the LTM, followed by a recall test.P: Each of the 24 student participants took part in a test which consisted of 8 trials. In each trial, the students were given a trigram to remember and a 3 digit number to count backwards from until told to stop. This prevented rehearsal of the trigram. The IV was the retention interval (amount of time before recall)- 3, 6, 9, 12, 15, 18 seconds.C: STM has an exceedingly short duration unless rehearsal is carried out.

BahrickA: To assess the duration of the LTM through recall tests.P: 329 17-74 year old Ohio participants provided their high school yearbooks and were tested by the investigators on the accuracy of their recall regarding the photo recognition of 50 students and free recall of all graduating class members.F: Recall in the form of photo recognition in those who graduated within the past 15 years was 90% but this figure fell to 70% in those who graduated within the last 48 years. Free recall in those who graduated within the last 15 years was 60% accurate while the accuracy of those who graduated in the last 48 years was 30%.C: The duration of the LTM is extensive.

Baddeley- This study relied on artificial stimuli in that the acoustically and semantically similar and dissimilar words tested were not meaningful in context.- Therefore Baddeley's research may not be applicable to all memory tests, particularly where the acoustic information (for STM tasks) is meaningful as it may be encoded semantically (in the LTM) rather than acoustically as a result.

Jacobs- Jacobs' research is arguably outdated and therefore lacked control and therefore the data may not be entirely valid due to the action of confounding variables such as participant distraction resulting in poor performance. + Jacobs' findings are echoed in other research, advocating its validity.

Miller- Miller's assumption (using commonplace grouping of 7 items) that STM capacity is 7 items +/- 2 may overestimate the capacity of the STM as other research such as Cowan contradicts these findings, limiting estimation of the STM capacity to 4 items- a figure on the lower end of Miller's proposed spectrum of 5-9.+ Cowan suggests that 4 chunks/items is the capacity of the STM- supporting Miller's theory that 5 words are as easily remembered as 5 letters.