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Inductive reasoning and implicit memory: evidence from intact and impaired memory systems
Authors: Luisa Girelli, Carlo Semenza and Margarete Delazer.
Appeared in Neuropsychologia 42 (2004)
Review by: Sonja Damnjanovic
Introduction Inductive reasoning – process of
inferring a general rule by inspection of specific instances
Inductive reasoning is essential in problem solving, development of expertise and learning
Typical examples of inductive reasoning tasks are ‘series completion’ problems
Series completion problem
Letter or number series completion are given to participants (e.g. A C E G or 2 4 8 16)
The task is to discover a general rule, which defines the relations between constituent elements. The rule has to be identified and applied to continue given series!
Purpose of the study
To investigate role of implicit memory in problem solving
Previous studies show that number series completion may be facilitated by a priming procedure
Priming effects in number series completion
Presented studies Experiment 1 – A) explores the time course of priming in number series
completion. The number of intervening trials between prime and the target varied (4 and 10)
B) explores whether the trials were explicitly remembered or not
Experiment 2 – used just the lag 4 and was designed to examine which stage in number series completion is the most sensitive to priming
Case study – amnesic patient’s performance on number series completion task
Experiment 1 Number series completion task
Experimental trials were mixed with filler trials Both experimental and filler trials varied in difficulty Primes and targets were separated by four trials (block1) or by
10 trials (block 2). Task: say aloud what number comes next
Recognition task
Similar to series completion design, but following different criteria
Experimental trials were either identical prime-target pairs or pseudo-pairs
Task: Answer whether the trial was presented
before !
Experiment 1
Results
- reliable priming effect!
- faster and more accurate answers for target series then for primes series
- Lack of significant difference between priming effects in lag4 and lag10 conditions
(they are both pretty long for priming)
-Difficulty of the trial influenced accuracy - Easy trials (floor effect): low error rate for primes and
targets- Performance on recognition task was poor-
excluding strategies of explicit recollection
Experiment 2 1. Series completion task – identical to
the Experiment1
2. Identification task – identify the algorithm without completing it
3. Extrapolation task – (e.g.,”+2” for 2 4 6 8 ; participants were to say 10).
Experiment 2 results
Discussion Experiment 2
Question: Whether priming can be attributed to different processing components?
Identification task – participants were faster and more accurate in identifying rules for targets in comparison to the rules for primes
Difficult tasks yielded larger priming effects (my comment: probably easy items were too easy) Authors comments: completion of easy and difficult
series relies on different subprocedures
Experiment 2
Extrapolation task - significant priming for difficult items only My comment: easy items, too easy to catch
the difference between primes and targets Processing differences between easy and
difficult problems
Case study
Case of amnesia:
PR, 55 years old Performance on memory tests: Average WM span, impaired autobiographical
memory, severe deficits in learning verbal and visual information
Other results in the table
- Tasks were the same as in Experiments
1 and 2
Results:
Significant priming for lag 4 series completion task (p<.0001) in both difficult and easy trials
Not significant priming for lag 10
Identification tasks Significant priming for difficult (p< .01), but not for
easy trials
Extrapolation task No significant difference
Recognition task There is no evidence that he was able to explicitly
recognize previously presented trials
General discussion Studies support the view that priming occurs
via implicit memory activation. Participants did not explicitly recognized previously presented trials.
PR shows the evidence that the priming doesn’t occur due to explicit processes
Long lasting priming (because of the lag 10) But lag of 4 is also long
Comments: Experiment 1. Lag 4 and lag 10 are
arbitrary and not too different
Experiment 2. Not sure that the stages are measuring what underlies priming.
Case study. Sample size of 1 might not reflect what is really going on.
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