Atkinson and Schiffrin's Model
Atkinson and Schiffrin
If sensory memory is paid attention to, it will go into short term memory.
If short term memory is rehearsed it will go into long term memory.
If short term memory is not rehearsed it will be forgotten through displacement and decay.
If long term memory is retrieved it will go back into short term memory.
If long term memory is not retrieved it can be forgotten through decay and interference.
- Memory is characterised as a flow of information through a system.
- Transfer requires re-coding
- Each stage has a capacity and duration
- Short term memory only lasts 18 seconds unless rehearsed.
Capacity: The amount of information that can be stored at any one time.
Duration: The maximum length that information can be held for.
Encoding: The format the information is represented in.
Encoding: Unprocessed, all the senses
Duration: Fraction of a second
Capacity: Huge - every stimulus in your environment
Baddeley et al 1988 suggested that the function is to give continuity such as from one eye fixation to the next when you are watching a film.
Short Term Memory Capacity
Miller 1956 found that the average person can recall 7 +/- 2 independent items. These may be letters, numbers or words and are called chunks. Chunks form due to what they mean in long term memory.
Long term memory can temporarily increase short term memory capacity. It was found that if digit strings were repeated within a series of immediate short term memory capacity trials they became increasingly easier to recall.
Reading aloud increases recall performance more than reading in your head.
Pronunciation time has been found to be more important than digit span. It was found that you can recall as many items as you can pronounce in 1.5-2 seconds. English speakers were found to have better recall performance than Arabic speakers. An explanation is that Arabic numbers take longer to pronounce.
Short Term Memory Duration
Short term memory is, by its nature, a temporary store. Items that need to be stored for longer are transferred to long term memory.
Peterson and Peterson
Procedure: Shown a consonant trigram, then asked to count backwards in threes to prevent rehearsal. After intervals of 3 seconds increasing participants were asked to recall the trigram.
Findings: 80% of trigrams recalled after 3 seconds. Less than 10% recalled after 18 seconds.
Evaluation: Trigrams are artificial so lacks ecological validity. Controlled so high internal validity.
Factors affecting duartion of STM:
Rehearsal: If we want to remember something for a short period of time we repeat it. This continually reinserts the information into short term memory and increases duration it is held.
Deliberate intention: In Sebrechts's surprise test recall fell to 1% in only 4 seconds. Without intention to recall capacity decreases.
Short Term Memory Encoding
You can encode information visually, accoustically or semantically. For example when thinking of a glove you may imagine an image of a glove, the sound of the word glove or situations in which a glove might be used.
Procedure: Participants were shown 6 constonants in rapid succession, either accoustically similar (P, C, T, V, B) or accoustically dissimilar (Y, F, K, L, H).
Findings: It was more difficult for participants to recall accoustically similar words than accoustically dissimilar words. This suggests short term memory is encoded accoustically.
Evaluation:Variables were controlled so high internal validity. The consonants are artificial things to remember so less ecological validity.
Factors affecting short term memory encoding:
Brandimonte et al found that if acoustic encoding is prevented then short term memory can also encode visually
Long Term Memory Capacity
This calls for a very organised structure to retrieve items. This suggests that there are a number of different systems in long term memory.
This explains why people with amnesia forget some things but remember others.
Long Term Memory Duration
Procedure: 392 graduates of one high school tracked down over 50 years. One group was asked to recognise their high school peers in their yearbook by matching names to pictures. The other group was asked to recall the names of their peers with just the pictures.
Findings:Recognition group: 90% after 14 years. 60% after 47 years
Recall group: 60% after 7 years. Less than 20% after 47 years.
Conclusion: Some information can be remembered for almost a lifetime.
Long term memory is better when measured by recogniton rather than recall.
Evaluation: Realistic stimulus means high ecological validity. Unclear whether accuracy drop after 47 years is due to duration or general decline of memory in old age.
Things affecting duration: Childhood amnesia: no organised memories available for recall. Measurement type: Whether recognition or recall can affect results.
Long Term Memory Encoding
Procedure: Participants were given 10 words from a group of either accoustically similar, accoustically dissimilar, semantically similar or semantically dissimilar.
Findings: 55% of sematically similar words were recalled compared to 85% of semantically dissimilar words. Acoustic words had no differences.
Conclusion: Long term memory encodes semantically.
Evaluation: Only a correlation was found as there was no control group. This means a causality cannot be established.
Things than can affect long term encoding:
We can recognise sounds shows that long term memory can encode acoustically. We can picture faces which show that long term memory can encode visually. This suggests that the type of stimulus can affect the encoding of long term memory.