Monday, July 19, 2010

Causes of forgetting (for Bronnie)




NON-ORGANIC
Retrieval Failure Theory
-Retrieval failure theory is sometimes called cue dependent forgetting because we fail to retrieve information due to the use of inappropriate or faulty cues.
- a retrieval cue is a stimulus that helps recover information stored in memory. a question is a cue, such as "where did you go on the weekend?"
-this theory supports the semantic network theory because it suggests that to be able to access pieces of information cues or links to other information are req
uired.


(animals cue)




Motivated forgetting
-Sigmund Freud developed this theory.
-Motivated forgetting is forgetting that arises from a strong desire or motive to forget, usually because the event is to traumatic to remember.
Repression is unconscious motivated forgetting and suppression is conscious motivated forgetting.
-Because a memory could could bring back unpleasant feelings and thoughts a person defends themselves from the unpleasantness by repressing the memory. Repressed memories are not lost from memory but are not easy to access in NWC, however they are sometimes evident in dreams or when a person fumbles for words or blushes when a certain topic is raised. Freud belived that repressed memories can only be consciously accessed after the unpleasant emotion that is associated with the event is diffused.
-This theory is limited because it cannot be tested in an experimental setting due to the fact it is only associated with traumatic experiences.

Interference theory of forgetting

This theory suggests that forgetting in LTM occurs because other memories interfere with information trying to be recalled, particularly memories that are similar.
-Retroactive interference occurs when new information interferes with the retrieval of previously learnt information. such as if you revise for psych, then biology, then have your psych exam the biology information may interfere with the retrieval of the previously learnt psychology information.
-Proactive interference is when previously learnt information interferes with the retrieval of newly learnt info.

Decay theory
This theory proposes that forgetting occurs because over time a memory fades through disuse.
-One study showed that there was a pattern of deactivation of neural pathways in the part of the brain associated with the consolidation of memory, supporting the decay theory.
-However the use of correct cues can retrieve information that was through to be lost this evidence contradicts the decay theory.



ORGANIC
-organic forgetting is forgetting as a result of something phsysiologically based such as disease, stroke, head injury, long term alcoholism, drug use, sever malnutrition or ageing.

Amnesia
-You can get amnesia through the injury, removal or disintegration of the part of the brain called the Hippocampus.


Anterograde amnesia

-anterograde amnesia is the loss of memory of events and information received after the damage to the brain that caused the amnesia. For a sufferer, information enters sensory memory and when attended to moves to STM where it can be manipulated and rehearsed but the physical structures involved in storing it in the LTM are damaged and so it is not stored and forgetting occurs.


-Imagine meeting someone for the first time, being introduced and starting to talk only to have forgotten who they are, what their name is and why you are talking to them, this is what people with anterograde amnesia experience. (Unless they constantly reherce the information to keep it in the STM).





-H.M. who was suffering from server epileptic seizures that originated in his temporal lobe had portions of his temporal lobe removed as well as the hippocampus. As a result of his surgery though most of his cognitive functions where unaffected he forgot information that entered his STM as soon as he stopped rehearsing it. He was unable to form new semantic or episodic memories.

-Anterograde amnesia may last until death or for a short period of time depending on the extent of the brain damage and the brains ability to recover.



Retrograde amnesia
-Retrograde amnesia is the loss of the memory of events or information prior to damage of the brain. Memories usually return over time (could be hours, days, moths or even years) however sufferers never recover the memory of what happened directly before the damage. This total loss of a memory is due to the consolidation period of the memory being interrupted by the damage to the brain, not allowing the memory to properly stabilise and be stored in long term memory.

Imagine waking up in hospital and not knowing why you where there not knowing the people around you or what the date is. this is what people with retrograde amnesia can experience depending on the severity of the damage.








-An English neurologist Ritchie Russell reported a case in which the patient sustained damage to the left frontal lobe and had no memory of the last 7 years of his life. After two weeks he was able to remember up until two years prior to the damage and it took another 8 weeks for him to fully remember the events in his life.

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