Cognitive Psychology - Studies and Experiments
Encoding of Memory
Baddely (1966) tested the effects of acoustic and semantic similarity on short-term and long-tern recall.
Baddely split participants into 4 different groups (A, B, C and D).
Group A was given the following, acoustically similar, list of words:
- Cat, cab, can, cad, mad, max, mat, man, map.
Group B was given the following acoustically dissimilar list of words:
- Pit, few, cow pen, sup, bar, day, hot, rig and bun.
Group C was given the following semantically similar list of words:
- Great, large, big, huge, broad, long, tall, fat, wide and high.
Group D was given the following, semantically dissimilar, list of words:
Good, huge, hot, safe, thin, deep, strong, foul, old and late.
The different groups were all read 12 sets of 5 words picked at random from their list at a rate of one word per second.
After the words were read to them the participants were given a list with all of the words of their list on them (it's the order of recall that mattered, not remembering the actual words).
They were then asked to recall the 5 words in the correct order that they were read to them.
A score was then calculated for each participant from 1-12, depending on how many sets of words they remembered.
Baddely found that participants had trouble recalling acoustically similar words from their Short-Term Memory (STM) but not from their Long-Term Memory (LTM).
He also found that the opposite happened with semantically similar words - participants had no problem recalling them from their STM, but found that the words got mixed up when in their LTM.
Baddely's results indicate that the STM encodes information acoustically whereas the LTM encodes information semantically.
Capacity of Memory
George Miller (1956) investigated the number of objects an average human can hold in the working 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 subject was asked to identify each tone relative to the others that they had already heard, by assigning it a number.
When it reached approximately 5 or 6 tones the participants began to get the numbers and tones confused.
Miller did this study not only with tones but with things such as numbers and words.
Miller found that participants could on average only recall between 5 and 9 things before getting confused.
Miller concluded that the span of immediate memory is 7+-2.
Multi-Store Model of Memory
The Multi-Store Model of Memory (MSM), produced by Atkinson and Shiffrin in 1968, is an explanation of how memory processes and stores work (read this hub for more details on the MSM).
Glanzer and Culnitz conducted research to support this model.
Glanzer and Cunitz (1996) investigated the MSM and the idea that memory consists of three unitary stores.
Participants were given a list of 50 words that they needed to memorize in a given amount of time and then asked them to recall the words they remembered.
This experiment found that there was a 'recency effect' where the participants remembered the most recent words that they had read because they had not yet been displaced from their STM.
Glanzer and Culnitz also found that participants showed a 'primary effect' in their recall of words where they remembered the first words on the list because they had been rehearsed more and thus transferred into their LTM.
The findings of Glanzer and Culnitz's study support the MSM support the idea that there are differences between the STM and the LTM and that they are 2 separate, unitary memory stores.
Working Memory Model
The Working Memory Model (WMM) is a model Baddely and Hitch proposed 1974 as an alternative to the Multi-Store Model of Memory.
The WMM represents one aspect of memory - short-term memory (STM) or immediate memory.
Shallice and Warrington (1970) conducted a study to try to support the WMM and it's different components (read this hub for details of the WMM)
Shallice and Warrington conducted an experiment into a person known as 'KF'.
KF had brain damage and could process visual information without any problems but could not process acoustic information in the form of letters and numbers (however he could process semantic acoustic information).
He also had no problems with his long-term memory but his immediate short-term memory seemed to be impaired.
This showed that his brain damage seemed to be restricted to his Phonological Loop.
The findings of Shallice and Warrington's study supports the Working Memory Model.
Loftus and Palmer (1974) investigated the accuracy of memory by using leading questions to try and distort the immediate recall of someone who witnessed a car crash.
Loftus and Palmer showed 45 participants (students) 7 films of different car crashes.
After watching the films, the participants were asked to fill out a questionnaire which involved asking them specific questions to get them to describe the accident that they just witnessed.
One question in the questionnaire was 'About how fast were the cars going when they ... ?'.
5 different verbs were given to 5 different groups of participants to describe the crash.
One group was asked 'About how fast were the cars going when they contacted?'
The other groups were given the verbs 'hit, bumped, collided and smashed'
The mean speed estimate was then calculated for each group.
On average participants who were given the question with the verb 'smashed' estimated that the speed was 40.8% whereas the group given the word 'contacted' estimated that the speed was about 31.8%.
The results show that people's recall and memory can be distorted by the use of leading questions.