long term memory Flashcards
what is long term memory
Archive of information about past events and knowledge learned
storage from a few moments ago to as far as one can remember
evidence between STM AND LTM
-serial position data
-neuropsychological data
serial position curve
-graph is u-shaped
**particpants remember words at the beginning of the list (primacy effect)
and end of list pretty well (recency effect)
**participants use rehearsal to memorize list and repeat the first word over and over
Why is memory better for stimuli presented at the beginning of the list(primacy)
rehearsal(more likely to enter long term memory)
Why is memory better for stimuli presented at end of list(recency)
Stimuli still in short term memory
**recency dissapears if there’s a delay between encoding and retrieval
neuropsychlogical data: Patient HM
Medial temporal lobe removed bilaterally including hippocampus
severe LTM problems, intact STM,
no trouble with language or motor tasks (could do digit span task)
Lessons from HM
1)there is distinctions between STM and LTM
**Clive and HM have STM intact, but impaired LTM
patient KF
difficulty with short-term memory (digit span) but intact long term memory (accident;damaged parietal lobe)
how? similarities in coding between STM and LTM
coding
Coding:the form in which stimuli are represented “in the mind”
3 types of coding for STM AND LTM
1)visual
2)auditory
3)semantic
short term coding(fruits experiment)
proactive interference in fruits group—(information from the past disrupts current processing and is a major source of confusion and errors in short term memory)
Coding in a semantic way, they are semantically related so its hard to keep it all in your mind
professions group had release from proactive interference
Other Caveats
Under some circumstances, some patients with damage to hippocampus have damage to short term memory tasks
**Hippocampus is active during the delay of a short term memory task, particularly when stimuli is novel
Lesson 2 from H.M.
Episodic vs semantic memory
When H.M. was asked about his past, he could remember facts about himself and the world(semantic memory) but could not remember any specific events(episodic memory)
**Suggests that damage to the hippocampus affects episodic memory but less so semantic memory
in healthy brain
semantic and episodic memory are intact… but they can dissociate after brain injury
retrograde and anterograde amnesia
both co occur (happen at same time)
Lesson 3 from HM
explicit(delcarative) memory includes both episodic and semantic memory
implicit memory include procedural, priming, and conditioning
hm retro and anterograde amnesia
hm cant remember events from past(retro)
hm cant form new episodic memories after surgery either(antero)
hm can learn a little bit of semantic knowledge but its very difficult
Anterograde memory:
cant make new episodic memories
**Amnesic anterograde patients have a hard time learning new facts(semantic) but they can learn some by repeating it over and over
Retrograde amnesia(presurgery)
episodic memories impaired
In retrograde amnesia semantic memory is intact
How time affects memories
Forgetting increases with longer intervals after encoding(the more time has passed), but we dont forget everything but the way we remember information changes over time
remember/know procedure
“Knowing experience” you know the person, but you cant recall how u know the person(sense of familiarity)
“Remembering experience”: you know the person and you remember how you know them
experiemnt of know/remember/dont remember on 50 yr olds
*As time passes you get more “don’t know” response
“Remember” responses decrease as well as “know” responses, but more decrease in remember responses
***Memories become semanticized over time, loss of episodic detail in long ago events
developmental amnesia
very early in life occurs due to oxygen loss in the brain causing a reduced volume size of hippocampus during birth (pre or perinatal)
*Does Not affect surrounding areas besides hippocampus such as amygdala, medial temporal lobe cortices
*intact semantic knowledge
*dont have episodic memory, they do fine on MC tests bc they tap into recogntion memory (their recognition memory seems be based on sense of familiarity and not on recollection)
testing developmental amnesic patients on “know” paradigm
If you ask a patient with developmental amnesia whether they recollect, its hard for them to answer because its based on subjective experience
**they cant recall the encoding context(only familiarity)
developmental amnesiac patents only have
anterograde amnesia(since they were born with it)
they have intact semantic knowledge
2 reasons to explain why developmental amnesiacs only have anterograde amnesia and intact semantic knowledge
1)developmental amnesia occurs very early in life, and because of plasticity other parts of brain are able to compensate for damage to hippocampus
2)damage is only on the hippocampus and not other parts of the brain
What is Implicit memory?
procedural, priming, conditioning
procedural memories are
skill memories
no memory of where or when learned
People who cannot form new LTMs can still learn
new skills (patient H.M., Clive Wearing)
Mirror tracing task:
A healthy control is placed in front of mirror, their job is to trace a star without looking down at paper, only in mirror
Patient HM has no episodic memory for doing the task, but his performance gets better over time, therefore he learns
Priming
Priming occurs when presentation of a stimulus changes a person’s response to a test stimulus
repetition priming
Test stimulus the same or similar to priming stimulus
Read and rate words. Next recall words (explicit memory task) and complete a stem completion task (implicit memory task that asks patients to fill in the rest of the word when given the first letter of each word)
b)amnesic patients did as well as the other patients on the implicit memory test (completing three-letter word stems)
Priming in everyday life:
propaganda effect
more likely to rate statements read or heard before as being true
**Involves implicit memory because it can occur when people are not aware of previously seeing or hearing statement
Classical conditioning and implicit memory in amnesic patients
Pairing a tone with a shock, later the tone alone triggers fear related or physiological behaviors
Patients with amnesia show intact forms of classical conditioning
Still show skin conductance and sweating responses(conditioned response) without explicit memory of ever hearing the tone, shock, or seeing experimenters
