dissociations Flashcards
Describe the typical pattern of memory impairment in (anterograde) amnesia, using empirical evidence
Hippocampus
- Spatial navigation and episodic memory
- Binds episodes together, (items space and time)
Amnesia patient 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 semantified and stored elsewhere
- Had an intact digit span
- Completely intact implicit memory
Implicit memory: preserved in anterograde amnesia
Priming:
- Fragmented picture identification
- Word completion
- Lexical decision
- Perceptual identification
- Object priming
Skill acquisition
Conditioning
(all no intention to retrieve from memory)
Explain the concept of a “dissociation” and a “double dissociation”
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
Double dissociation
- Same variable (study condition) has opposing effects on two tasks
- the example w three conditions, implicit and explicit had different results due to level of processing effects and hyper specificity effects
- much stronger evidence that they are different systems than single dissociation
Discuss evidence that explicit and implicit memory are two distinct memory systems
jacoby 1983 double dissociation between implicit and explicit memory
- Participants study “COLD” in all conditions
3 study conditions:
- no context “xxx-COLD”
- context “hot-COLD”
- generate “hot-???”
then 2 recall conditions
- Recognition (old/new): cold, sweet, … (explicit memory)
- Word identification: ms word flashes on screen, must (implicit memory) identify whether they’re seen it or not
- found a double dissociation due to level of processing effects and hyper specificity effects
Explain the concept of “stochastic independence” and how this has been used to differentiate explicit and implicit memory systems
- Absence of any correlation between two probabilistic events or measures
- If the occurrence of Event A does not change the probability of Event B occurring, then Events A and B are independent.
- Obtain the joint probability of two independent events occurring together by multiplying their individual probabilities
- Because the observed probability of both events occurring P(A,B) = the expected probability of both events occurring P(A∩B), the events are independent.
Tulving and colleagues (1982)
- 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 which matched the observed
- Then did it after a 7 day delay again and it also matched the observed
- Recognising a world tells us nothing about whether the subject will use it in a fragment
- Found that explicit and implicit memory are entirely independent
- Odd considering that memory tests are usually not independent
- Suggest independent systems
Discuss the main assumptions of transfer-appropriate processing (TAP) theory
- The degree of Overlap between cognitive processes during study/test is critical
○ Eg large overlap = good performance and small overlap = bad performance - Explicit and implicit rests typically require different retrieval operations (meaning, explicit vs perceptual, implicit operations)
- TAP predicts dissociations along mode of processing not type of test
- Therefore presence or absence of overlap between study and test processes
Two classes 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 overlap between study and test operations for performance to be good
- Overlap between study and test must match for good performance
Cite a piece of evidence that supports TAP theory and a piece of evidence that TAP cannot handle
CAN HANDLE DOUBLE DISSOCIATION FOR IMPLICIT VS EXPLICIT
so in terms of the jacoby double dissociation, this might also be because of TAP. So to find which one is causing the dissociation w look at
Blaxton 1989
- got asked to do an explicit data-driven test: graphemic cued recall. eg which word on the list looked a lot like colony or plague
- got them to do a conceptual implicit test: trivial pursuit style eg: what disease was called the black death and what German city is famous for its scent
- Dissociation pattern better explained by TAP and its emphasis on study-test processing overlap
- when compared to norm
PROBLEMS
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)
Explain what is meant by conscious contamination
Problems with conscious contamination
- How can we be certain that implicit is truly implicit?
- Conscious recollection of other implicit tests
- The extent of conscious contamination we must control for conscious contamination to see if its truly implicit memory
Explain the process-dissociation procedure and how it can give more “process-pure” memory measures
◆ 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
