trace decay trace decay the theory suggests that learning causes a physical change in the neural...
DESCRIPTION
Once this memory trace has been created, it must be reinforced through repetition to strengthen it If the trace is not reinforced by practice it will simply weaken and decay, causing forgetting to occur. We need to use it or lose it!TRANSCRIPT
Trace DecayTrace Decay
Trace decayTrace decay The theory suggests that learning causes a The theory suggests that learning causes a
physical changephysical change in the in the neuralneural network of the network of the memory system, creating a memory trace or memory system, creating a memory trace or “engram”“engram”
Hebb (1949) looked at the brain and showed Hebb (1949) looked at the brain and showed that a memory occurs when a group of nerve that a memory occurs when a group of nerve cells excite (stimulate) one anothercells excite (stimulate) one another
engram
noun
a postulated biochemical change (presumably in neural tissue) that represents a memory
EngramEngram = biochemical change (presumably in neural tissue) that = biochemical change (presumably in neural tissue) that represents a memoryrepresents a memory
Once this memory trace has been Once this memory trace has been created, it must be reinforced created, it must be reinforced through repetition to strengthen it through repetition to strengthen it
If the trace is If the trace is not reinforcednot reinforced by by practice it will simply practice it will simply weakenweaken and and decaydecay, causing forgetting to , causing forgetting to occur. We need to use it or lose it!occur. We need to use it or lose it!
Trace Decay (STM)Trace Decay (STM)
So, trace decay explains forgetting as So, trace decay explains forgetting as a problem of a problem of availabilityavailability – that is, the – that is, the information is information is lost completelylost completely from the from the memory system through disuse and memory system through disuse and passage of timepassage of time
Biological processes in the brain cause Biological processes in the brain cause the trace to decay until eventually the the trace to decay until eventually the message it carried, is lostmessage it carried, is lost
Trace Decay Experiment Trace Decay Experiment Ethics Ethics This experiment aims to investigate one This experiment aims to investigate one
aspect of memory.aspect of memory. You do not have to participate.You do not have to participate. You may withdraw at any time.You may withdraw at any time.
Trace decayTrace decayYou will see a trigram cardYou will see a trigram cardAfter this you will be asked to count backwards After this you will be asked to count backwards from 50 in 3’sfrom 50 in 3’s
Ready…..Ready…..
FHTFHT
Count Count
RecallRecall
KLBKLB
Count Count
RecallRecall
MCFMCF
Count Count
RecallRecall
HYCHYC
Count Count
RecallRecall
DJRDJR
Count Count
RecallRecall
MCGMCG
Count Count
RecallRecall
PDCPDC
Count Count
RecallRecall
PSFPSF
Count Count
KCBKCB
Count Count
RecallRecall
HSJHSJ
Count Count
RecallRecall
Supporting Evidence for Trace Supporting Evidence for Trace Decay TheoryDecay Theory
Peterson & Peterson (1959)Peterson & Peterson (1959) Had participants recall trigrams after varying intervalsHad participants recall trigrams after varying intervals During rehearsal an Interference task was given (counting backwards in During rehearsal an Interference task was given (counting backwards in
threes) to prevent rehearsalthrees) to prevent rehearsal They found less that 10% of information was recalled after 18 secondsThey found less that 10% of information was recalled after 18 seconds This is evidence for trace decay in STM. Participants weren’t able to This is evidence for trace decay in STM. Participants weren’t able to
practice/repeat the information/memory, and so the memory traces practice/repeat the information/memory, and so the memory traces decayeddecayed
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EvaluationEvaluationHowever, a weakness of this research is that it However, a weakness of this research is that it was conducted in a laboratory. Consequently, was conducted in a laboratory. Consequently, the experiment involved artificial tasks (lacked the experiment involved artificial tasks (lacked --------------------------) and an unnatural setting, --------------------------) and an unnatural setting, and therefore (lacked________________)and therefore (lacked________________)So the results may not be valid in the “real So the results may not be valid in the “real world”, and therefore this study cannot easily world”, and therefore this study cannot easily be generalised to how we use memory in the be generalised to how we use memory in the real world.real world.
Evaluating the trace decay theory Evaluating the trace decay theory of forgetting – AO2of forgetting – AO2
- One problem is the theory is One problem is the theory is limitedlimited. . There are things that it cannot explain. There are things that it cannot explain. The problem is that we The problem is that we dodo recall things we recall things we have not thought about for a long time. For have not thought about for a long time. For example we can ride a bike after a long example we can ride a bike after a long period. We have not been renewing the period. We have not been renewing the physical memories in the meantime, but physical memories in the meantime, but the memory is still there.the memory is still there.
Sometimes, after being presented the Sometimes, after being presented the appropriate cues, memories are triggered appropriate cues, memories are triggered and long-forgotten memories rememberedand long-forgotten memories remembered
This suggests the engram did not decayThis suggests the engram did not decay
- Many elderly people can recall incidents from their Many elderly people can recall incidents from their youth in great detail. Unless they have recalled the youth in great detail. Unless they have recalled the instance many times throughout their lives, the trace instance many times throughout their lives, the trace should have decayed according to trace decay theory.should have decayed according to trace decay theory.
- If the trace decay theory is correct, and you hadn’t If the trace decay theory is correct, and you hadn’t played the guitar for 20 years then not only would you played the guitar for 20 years then not only would you be unable to recall the chord sequence for a particular be unable to recall the chord sequence for a particular song, but it would also take you as long to learn the song, but it would also take you as long to learn the song the second time as it did the first. This simply song the second time as it did the first. This simply isn’t true.isn’t true.
- People under hypnosis can often recall things that People under hypnosis can often recall things that they haven’t thought about for years, so their traces they haven’t thought about for years, so their traces may still be intact.may still be intact.
- Trace decay cannot explain why some people seem to Trace decay cannot explain why some people seem to have have poor recallpoor recall of even of even recentrecent events, while others events, while others have have incredible memoriesincredible memories going going back for decadesback for decades. .