6. L6 dissociations of memory Flashcards
the hippocampus
- Spatial navigation and episodic memory
- Binds episodes together, (items space and time)
amnesia patient Henry moliason (HM)
- Surgery removed parts of his medial temporal lobes bilaterally, including both hippocampi
- after surgery he was not able to form any new memories (anterograde amnesia)
○ Anterograde: not being able to form any new memories after the event - Old memories intact from his childhood but lost recent ones (ribot gradient)
○ Old memories become hippocampus independent as they become sanctified and stored elsewhere - Had an intact digit span
- Completely intact implicit memory
how do we see implicit memory preserved in anterograde amnesia
Priming tasks perform well:
- Fragmented picture identification
- Word completion
- Lexical decision
- Perceptual identification
- Object priming
Skill acquisition remains
Conditioning remains
(all no intention to retrieve from memory)
single dissociation definition
- Independent experimental variable has an effect on one but not the other type of test.
- Used to argue there’s something difference between these two tasks and therefor difference in types of memory
Dissociations found (jacoby, 1983) when testing hyper specificity and Levels of processing effects
Three conditions
1. Provided words with no context: xxx - cold
2. With context :hot - Cold
3. Word to be remember was not presented only antonym as a cue and participants to generate the word: xxx - cold
- Participants study cold in all conditions
- Then are asked to recognise if words were and or new from a list eg, sweet, dark, cold (explicit memory test)
- Word identification task where words are briefly flashed on screen and must identify is its old or new ( implicit memory test)
found that:
- Hyper specificity : implicit
- Levels of Processing effect: explicit
The same variable has opposing effects on two tasks
catalogue of dissociations found for implicit vs explicit
Explicit but not implicit
- Levels of processing
- Study time
- Imagery
- Retention interval
- Alcohol intoxication
- Psychotropic drugs
- Age
Implicit but not explicit
- Surface form for example, font colour
- Modality
stochastic independence
- The absence of any correlation between two probabilistic events or measure
- If the occurrence of event A does not change the probability of event B occurring then thee events are different
- P(A∩B) = P(A) x P(B)
- Less than 2/8 means not independent therefore less than 25% because .50 x .50 is .25
stochastic independence measured by Tulving and collegues
- Gave participants list of words to study
- Got them do to recognition task (explicit)
- Then fragment completion task (implicit)
- Then run stochastic independence formula to see if they’re independent (.507)
- Then did it after a 7 day delay again (.375)
- Recognising a world tells us nothing about whether the subejct will use it in a fragment
- Found that explicit and implicit memory are entirley independent
- Odd considering that memory tets are usually not independent
- Suggest independent systems
Transfer appropriate processing (TAP) origins
Came about because the authors noted that implicit and excplicit memory tests are often always perceptual and data driven (implicit) and Meaning/concept based (explicit) and perhaps this is the distinction which is important to explain in the explicit/implicit dissociation
TAP assumptions
- The degree of Overlap between study/test processing is critical
○ Eg large overlap = good performance and small overlap = bad performance - Explicit and implicit rests typically require different retrieval operations (meaning vs perceptual operations)
- TAP predicts dissociations along mode of processing not type of test
- Therefore presence or absence of overlap between study and test processes
TAP and encoding specificity
- The principle of encoding specificity deals with environmental context, internal states, retrieval cues, while TAP focuses on the actual task at hand and the cognitive processes it involves
- TAP is thus a theory of memory that incorporates the encoding specificity principle
Two classess of operations in TAP
Conceptually based meaning driven processing
- Based on meaningful processing
○ At study: semantic or deep encoding
○ Top-down processing - thinking about the material
○ Internally generated no sensory input
○ At test: recognition or recall, free recall
○ Usually relies on meaning
Perceptual-based or data-driven
○ Based on perceptual processing
○ Looking at something and responding to what you see
○ Reading without context, lexical decision, word identification, fragment completion
- There needs to be an overlap between study and test operations for performance to be good
- Overlap between study and test must match for good performance
TAP strengths and weaknesses
- TAP handles many results involving unimpaired participants
○ (Superior) alternative to implicit/explicit memory systems view - Amnesic data present problems
○ Priming in amnesic patients is preserved even on conceptually driven implicit tests (Cermak et al., 1995)
○ Explicit memory is disrupted even on data-driven explicit tests - Data-driven vs. conceptually-driven is not a dichotomy
- Many tasks (esp. recognition) are both (and TAP can handle that)
Implicit vs. explicit offers a clearer criterion (retrieval intention)
problems with unconscious contamination TAP
process dissociation methodology
- How can we be certain that implicit is truly implicit?
- Conscious recollection of other implicit tests
Process dissociation methodology
- Implicit memory: U (unconscious activation)
- Explicit memory: R (conscious recollection)
- We want to measure U and R but we only get contaminated measures
- In one case, let R act in concert with U
○ Inclusion condition → estimate of U + R
- In another case, put R into opposition to U
○ Exclusion condition → estimate of U
- Difference between conditions: R
