Memory

• Describe encoding, storage and retrieval in STM, and LTM
• Show knowledge and understanding of Atkinson and Shiffrin’s two-process theory
• Be able to describe and evaluate theories of forgetting, interference, and motivated forgetting;
• Describe the use of organisation and imagery in aiding memory (mnemoics) applications e.g. study skills

Encoding

When information comes into our memory systems, it needs to be changed into a form that the system can cope with. For example, a word which is seen, heard or read may only be store if it is changed (encoded into an image, a sound or a meaning.

Storage

This concerns the nature of memory stores, that is how long they last, how much they can hold and what kind of information they hold.

Capacity

You can test your own short-term memory storage capacity by using the lists below. Read each horizontal line of numbers to yourself, then cover up the numbers immediately. Repeat the numbers and check your answer. What is the longest sequence of digits you can remember?

Miller (1956)

Chunking

At the end of 2 minutes write down all the letters that you can remember in the 7 x 7 grid.

You will find the answers at the end!

Miller found, that the actual amount of information STM can hold can be greatly increased by a process known as chunking. This refers to the grouping of items into larger units or chunks.

Retrieval

This refers to getting information out of a memory store. There are a number of different kinds of retrieval:

• Recall.
• Recognition.
• Reconstruction.

Atkinson and Shriffrin’s Multistore model of memory

Atkinson and Shiffrin (1968) suggest that memory is made up of a series of stores. These are the short-term memory (STM) and the long-term memory LTM. The stores differ in their encoding, storage and retrieval characteristics.

The short-term memory

• The STM holds information in the form of images, sounds, or meanings e.g. information about a word might be stored in terms of its appearance, how it sounds or what it means.
• We can store seven items (= or- two) in STM. The items can be chunks of information e.g. a telephone number with twelve digits could be reduced to three or four chunks.
• Items in STM last up to 30 seconds.

Peterson and Peterson (1959)

Gave participants a three-consonant trigram to remember (e.g. KDL) and then a large number (e.g. 485) immediately afterwards. To prevent participants from rehearsing the trigram, they had to count backwards in threes from the number for a time and then recall the trigram. The longer the participants counted, the less likely they were to recall it. The point at which they could not recall it gives us an idea of how long STM lasts, i.e. a maximum of 30 seconds.

Miller (1956)

Used memory span procedures to test how many items participants could hold in the STM. Using strings of number or consonants he found the average number of items was seven (Miller’s magical number seven), give or take two. This means out STM is capable of holding between five and nine items.

The Long-term memory

Information that is rehearsed enough will transfer into LTM.

• Information in LTM is encoded in may forms – we know LTM contains knowledge, facts, beliefs, pictures, skills, language and musical knowledge among many other things;
• LTM seems to have an unlimited capacity; LTM seems to have a indefinite lifespan;

Evaluation of Atkinson and Shriffrin’s model of memory

• The model suggests rehearsal helps transfer information into LTM but some studies show it is not essential. We may, for example, remember parts of a lecture or a book simply because they are funny, interesting or relevant in some way.
• Atkinson and Shriffrin thought everything was held in the same LTM but this doesn’t seem very likely. Other psychologists have argued we have more than one kind of LTM.

Organisation in LTM

Information in LTM is not stored any old how. It tends to be organized.

Bower et al (1969) showed how presenting words organized into categories helped people to recall 65% of the words compared to 19% if the same words were disorganized. They also found evidence that people spontaneously categorized disorganized lists.

Collins and Quillian (1972) thought that information in LTM was organized into hierarchies. When we want to retrieve something we start at the top of the hierarchy and work down until we find it. E.g. for information on ‘sticklebacks’ we might start at ‘animals’ move to ‘fish’, then to ‘freshwater fish’ and on to ‘small fish’ until we find what we want.

Imagery

Atkinson (1975) pointed out that good learners used imagery when learning a foreign language.

Method of loci

Imagine a road you know very well or a large building. You place the items that are to be remembered in different places in the building. When you need to remember them you simply walk down the road and collect the items.

Explanations of forgetting

Forgetting is the inability to recall or recognise information that was once stored in memory and has now disappeared (not available), or can’t be ‘brought to mind’ (not accessible). Since STM has limited capacity and duration, the explanations for forgetting in STM are likely to be due to lack of availability (it has disappeared) rather than accessibility (being unable to ‘find’ it).

Interference

One set of information competes with another, causing it to be ‘overwritten’ or physically lost. There are two forms of interference:

• Retroactive (RI) – a second set of information ‘pushes out’ earlier material. This could happen when someone learns French and then learns Spanish.
• Proactive (PI) – previous learning interferes with current learning. If you go to your local shops and they have rearranged the goods in the shop, then you will continue to go to the place the goods used to be.

Mcgeoch and McDonald (1931)

• recall was poor (12%),
• nonsense syllables interfered less (26% recall), and
• numbers even less (37% recall). Only interference can explain such findings.

Evaluation

• Interference has limited application.
• It is relevant to occasions when two sets of data are very similar.
• This is rare in everyday life but it does occur.

Repressed memories

Repression is a form of forgetting. Freud (1901) argued that painful or disturbing memories are put beyond conscious recall as a means of protecting one’s ego from anxiety. The kinds of memory that are ‘forgotten’ or repressed range from the serious, such as childhood incidents of sexual abuse or extreme unhappiness, to more commonplace situations like ‘forgetting’ to clean your room.

Trace decay

The physical trace simply disappears because it is not rehearsed or processed sufficiently. Peterson and Peterson provide evidence that data in STM disappears.

Evaluation

The disappearance of a memory trace may be due to interference rather than spontaneous decay, i.e. if nothing else entered STM it wouldn’t disappear.

Exercise 1:

Story

a)

'John was trying to fix the birdhouse he was pounding the nail when his father came out to watch him and to help him do the work.'

Story

b) The War of the Ghosts An American Indian folk tale

One night two young men from Egulac went down to the river to hunt seals, and while they were there it become foggy and calm. Then they heard war cries and they thought, 'Maybe this is a war party.' They escaped to the shore and hid behind a log. Now canoes came up and they heard the noise of paddles and saw one canoe coming up to them. There were five men in the canoe and they said:

'What do you think? We wish to take you along. We are going up the river to make war on the people.' One of the young men said, 'I have no arrows.' 'Arrows are in the canoe,' they said. 'I will not go along. 1 might be killed. My relatives do not know where 1 have gone. But you,' he said, turning to the other, 'may go with them.'

So one of the young men went and the other returned home.

And the warriors went up the river to a town on the other side of Kalama. The people came down to the water and they began to fight and many were killed. But presently the young man heard one of the warriors say: 'Quick, let us go home, that Indian has been hit.' Now he thought, 'Oh they are ghosts.' He did not feet sick but they said he had been shot.

So the canoes went back to Egulac and the young man went ashore to his house and made a fire. And he told everybody and said, 'Behold 1 accompanied the ghosts and we went to a fight. Many of our fellows were killed, and many of those who attacked us were killed. They said 1 was hit and 1 did not feel sick.'

He told it all, and then he became quiet. When the sun rose he fell down. Something black came out of his mouth. His face became contorted. The people jumped up and cried.

He was dead.

Amnesia

Amnesia refer to loss of memory due to e.g. bang on the head, a stroke, disease, or excess alcohol.

Anterograde amnesia is the inability to store new memories after a brain injury.

Milner (1966) reported on a young man,, referred to as HM, who was left with severe memory impairment after brain surgery. He was able to talk normally and to recall accurately events and people from his life before surgery, and immediate digit span was within normal limits.

He was, however, unable to retain any new information anc could not lay down new memories in LTM. When told of the death of his favourite uncle, he reacted with considerable distress. Later, he frequently asked about his uncle and, on each occasion, reacted again with the level of grief appropriate to hearing the news for the first time.

The case of Clive Wearing (based on Baddeley 1997)

Clive Wearing was highly educated, talented musician and broadcaster who contracted a viral infection called encephalitis in 1985. Tragically, this disease left him with extensive brain damage, which as caused major memory disruption. He is still able to talk, read and write and has retained remarkably intact musical skills. He can still sight-read music and is able to play quite complex pieces on the piano and harpsichord. In all other respects, however, his memory is dramatically impaired.

His memory for past events is his life is hazy although he can recall certain key highlights with prompting. His visual memory is impaired and he is unable to recognize pictures of his old Cambridge college where he had spent four years of his life and which he had visited many times in subsequent years. He has identified the Queen and the Duke of Edinburgh in a photograph as people who had once sung in one of his choirs. His general knowledge is also reduced and he has no idea who wrote the play Romeo and Juliet. Nor can he recall anything about the composer Lassus, in spite of having written a book about him.

Even more disturbing is his apparent inability to lay down new memories. Clive is convinced that he has only just woken up and he keeps a diary in which he records this obsessive thought. There are pages of closely written text in which he gives the date and time followed by the statement: ‘I have just regained consciousness.’ Or ‘I’m conscious for the first time.’ Whenever his wife visits, he greets her effusively as if he has not seen her for ages. If she leaves the room for a couple of minutes, the emotional greeting is repeated and this can happen time and time again.

It is now 15 years since the onset of the illness which caused Clive’s memory loss and he is still trapped in an eternal present – he cannot use the past to anticipate the future. He is unable to enjoy books or television because he cannot follow the thread and he does not read newspapers because he has no context within which to embed the news stories. He cannot go out alone because he immediately becomes lost and he is unable to tell anyone who finds him where he is going or where he has come from. Clive himself has described his situation as ‘Hell on earth. It’s like being dead’.

Retrograd amnesia refers to the loss of memory for a period before the injury, e.g. loss of memory for an hour before a car accident.