Specification of 'memory'
What is memory?
- The ability of the mind to store and recall past situations, thoughts & knowledge;
- The sum of everything retained by the mind.
There are 3 stores
sensory memory --> short term memory --> Long term memory
- Each store has a diiferent 'duration', 'capacity' & 'encoding'.
What does duration mean in terms of memory?
- How long the information stays in the memory.
The duration of the sensory memory...
- less than 1 second.
The duration of the short term memory...
- Between 18-30 seconds. Researched by Peterson and Peterson (1959)- Trigrams.
The duration of the long term memory...
- The long term memory can hold information for many years.Quite how long is unknown. Although loss is fast to begin with, hense little is remembered from younger years, it gradually slows down and allows more information to be stored.
Peterson & Peterson 1959 (Trigrams) STM
Aim: Peterson & Peterson did an experiment into the duration of the short term memory.
- P's asked to remember 3 consonants (used so could not be linked/rehersed and transfered) such as BHJ <-- this would be the Trigram.
- P's then given interference task, such as counting backward in 3's from 100 to ensure that P's were not rehersing trigrams. (Impaortant because rehersal could start to impliment the LTM in the learning process)
- Tested after 3, 6, 9, 12, 15 & 18 second intervals.
- Average recall of trigram was good - 80% after 3 seconds.
- Fewer trigrams recalled as intervals lengthened, Recall dropped to 10% after 18 seconds
- If reharsal is prevented, information vanishes rapidly from STM.
IV/DV/ EV & Evaluation of Peterson & Peterson 1959
IV- The differing time length intervals.
DV- The percent of correct recall of the trigrams
EV- If the trigram has some kind of semantic meaning, e.g initials.
- It suggests that decay is the mechanism for forgetting in STM.
- Lab study- therefore it was easier to control any possible extraneous variables
- Trigrams are artificial- Won't reflect every day memory.
- The inference task may have been responsible for the poor recall, not the time intervals that was the experiments IV.
Bahrick et al 1975 (picture face/name recognition)
Aim: to investigate the duration of the LTM.
- Sample of 392 american ex high school students raging from age 17-47.
- P's were tested on their recall of names of former classmates, name to photo recognition test, a set of 50 photos were shown as a photo recognition test and a name recall test was used with no pictures.
- 90% accuracy of face/name recognition after 48 years.
- Performance deteriorated after this.
- LTM had a long duration however we are not able to acess all information stored in there but when given a cue we can retrieve this information.
IV/DV/EV & Evaluation of Bahrick et al 1975
- High validity in terms of the task had a high mundane realism because they used the p's own memory instead of an artificial stimuli so reflexted their true behaviour.
- It was done in a lab which are controlled settings therefore has a high reliability because the tasks can be repeatedeasily to get similar results.
- Lacked population validity because the sample was restricted in terms of culture (only done in the US) therefore cannot be generalised to other individualist or collectivist cultures.
What does capacity mean in terms of memory?
- How much information can be stored in the memory store.
The capacity of the sensory memory...
Holds about 3/4 (3 quarters) of the information that enters it.
The capacity of the short term memory...
7 + or - 2 items or chunks of information. Researched by Miller 1956
The capacity of the long term memory...
Enormous, maybe even infinate. Its capacity is unclear.
Miller 1956 (auditory tones) STM
Aim: Miller did an experiment into the capacity of the short term memory.
- Miller got the participants in his experiment to listen to a number of auditory tones that varied in pitch (and pitch only).
- Each tone was played separately, and the P was asked to identify each tone relative to the others that they had already heard, by assigning it a number.
- P's could on average only recall between 5 and 9 before getting confused.
- Concluded that the span of short term memory is 7 +/- 2 items.
IV/DV/EV & Evaluation of Miller 1956
IV- The pitch of the sound.
DV-The amount of correctly identified tone.
Jacobs 1887 (Digit lists) STM
Aim: To investigate the capacity of STM.
- P's read a list of words and numbers and had to recall immediately after presentation in the order shown.
- In 50% Jacob did not use W or 7 because these had two syllables.
- He gradually increases the number of digits until P's could no longer recall them back in the correct order.
- Found a difference in recall between letters and numbers and a difference in the recall of age 9.3 numbers and 7.3 letters, an 8 year old recalled 6.6 digits whereas a 19 year old recalled 8.6 digits
- The STM has a limited capacity and a normal digit span is between 5 to 9 digits, also we develop a better strategy for recall as we get older.
IV/DV/EV & Evaluation of Jacobs 1887
IV- The collection of digits used to create each list.
DV- The amount of digits recalled correctly in the order given.
EV- If the list has semantic meaning to the P.
- Had high reliability because it was done in ost EVs can be controlled.
- Easily repeated to get similar results.
- Lacked ecological validity because it was a lab experiment so cannot account for everyday behaviour so cannot be generalised to other settings.
What does encoding mean in terms of memory?
- How the information 'gets into' the memory store.
- What sort of information is stored.
- How the memory is made.
The encoding used in the sensory memory...
Depends on the sense/senses used when collecting/recieiving the information i.e visual.
The encoding used in the short term memory...
Information is stored acoustically. Researched by Conrad 1964.
The encoding used in the long term memory...
Semantic encoding. words with meaning. Researched Baddeley.
Conrad 1964 (acoustic confusion) STM
Aim: was to investigate how information is encoded in the STM
- P's were presented with a sequence of 6 consonants with rapid exposures for each, they were then asked to recall the letters in order of presentation, there were two conditions:
- Condition 1: Acoustically similar letters such as P, D, T
- Condition 2: Acoustically dissimilar letters such as Y, P, X
- P's found it difficult to recall the letters that were acoustically similar but had no problem when it came to recall of the acoustically dissimilar letters.
- We must convert visually presented material into an acoustic form so it can be stored in the STM; therefore it is difficult to distinguish words that sound the same- acoustic code.
IV/DV/EV & Evaluation of Conrad 1964
- High reliability because it was done in controlled settings so results could be easily replicated to get similar results.
- Lacked ecological validity because it was done in a lab environment so cannot account for everyday behaviour.
- Lacked realism/ was unrealistic as the task was artificial so cannot show how people would act in real life.
Baddeley 1966 (semantically simi/dissim words) LTM
Aim: To find out what sort of encoding is used in the LTM.
- P's were shown a list of 2 lists:
- semantically similar & dissimilar words.
- Then were asked to recall after a 20 minutes.
- P's found it harder to remember semantically similar words (words with similar meanings).
- There was 55% recall for semantically similar words.
- 85% accuracy for semantically dissimilar words.
- Shows that words are semantically encoded in the LTM.
IV/DV/EV & Evaluation of Baddeley 1966
IV- The type of semantic word.
DV- The amount of words recalled correctly after 20 minutes.
EV- Other types of encoding may have been used in order to remember the information. e.g visual/acoustic.Also- The activity the participant did.
- Lab study, therefore its easier to control any extraneous variables.
- Artificial research- word lists would not be learnt in real life. therfore the recall task is not repesentative of everyday memory demands.
- There are other types of encoding used to transfer information into the LTM, which were not investigated in Baddeley's study.
- Individual differences, not everyone would have encoded semantically.
The Multi-store model (Atkinson and Shiffrin 1968)
Suggested that memory is made up of 3 distinct stores:
- Composed of our 5 senses.
- Information decays very quickly.
- If given attention, the information moves into the short term store.
Short term store:
- Information in this store will decay quickly if not rehearsed.
- Information can be displaced if new information enters (limited capacity).
- Maintenance rehearsal can move items from the STM to the LTM.
Long term store:
- Once here, information lasts for a very long time.
- Although if similar information enters the LTM it can interfer with the original information, causing it to be lost or changed.
Evaluation of the multi-store model
The primacy and recency effect:
- Glanzer and cunitz who used a serial position curve, in which words at a beginning of a list were easily remembered because they were rehearsed so enetered the LTM (primacy effect).
- Similarly words towards the end of the list were easily rememebred because they were also rehearsed a bit and so entered the STM (recency effect).
- Thus showing the STM and LTM are two different stores stores based on capacity and duration.
Evaluation of the multi-store model
Another positive evaluation point:
Brain damaged patients:
- If someone has good LTM before having an accident/illness that leaves someone brain damaged but after the accident can not transfer information from STM to LTM it provides strong evidence for 2 stores as it shows that there is a break within the 'chain'.
Evaluation of the multi-store model (weakness)
- Alot of research that supports the model is based on artificial tasks in lab setting - Lacks ecological validity and cannot be generalised to everyday life.
- Too simplistic- The processes that are involved in memory are more complex than the model suggests. It only suggests 3 models although there is evidence of the existance of more than one type of STM & LTM. (Working memory model- suggests STM is a store that can process sound and visual information (more than one store withing STM))
- Incidental learning suggests that it isnt just rehersal which LTM's. argued that the model ignores other factors.
- Simplistic- does not explain mechanism of the encoding process that changes acoustic information in STM to semantic in LTM which suggests that its the meaningfulness of the information which creates LTM's.
The Working memory model (Baddeley and Hitch 1974)
Suggests the STM is made up of 4 different stores:
- Most important component.
- Controls attention and allocates resources to other components.
- It has a very limited capacity so can only do limited things at a time.
- 2 parts: phonological store (inner ear) allows you to rehearse information acoustically and the articulatory process (inner voice) is used for words that are heard or seen.
- Stores visual and spatial information, such as faces.
- Visual = what things look like, Spatial = the relationship between things.
- Responsible for setting up and minipulating mental images.
- Has limited capacity.
The Working memory model (Episodic buffer)
- Integrates information from the other components into chunks or 'episodes'.
- Allows us to go beyond what is already in LTM and combine it in different ways. e.g an image of an elephant playing football can bring about memories from the LTM about elephants and football and then manipulate these to create a scenario.
Evaluation of the working memory model
- Support by other research evidence which could be explained by the MSM.
- McLeod (1977) performance impaired when P's played piano and sang at the same time. (both auditory tasks) which proves that store can be overloaded.
- The division of STM into other components accurately reflects evidence from brain damage patients. Remembering sounds, not words or visual stimuli.
- Not rigid- WMM is influential and still being developed and expanded. e.g the episodic buffer is a relatively new addition to the model.
- Relatively unknown- e.g the central executive is not very well known, but is most important, it has limited compacity but is not supported by much experimental research.
- Evidence comes from lab experiments- simplistic stimuli- lacks ecological validity and cannot be generalised to all memory processes in everyday life.