Psychology 3130A/B Chapter Notes - Chapter 12: Plos One, Conceptual System, Cluster Analysis

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Week 12 Expertise
- Novices and experts
- Expertise
o Perception and similarity
o Memory and categorization
o Judgement
o Problem solving
Look at 3 studies (look at parts highlighted in lecture)
What is an Expert?
- Experts know about a particular domain
- Aren’t “just smart”
o Although in many cases might also be very smart intelligence in of itself is not what we are
talking about
- At least 10 years of study/practice (Ericcson)
- Show differences in novices in ability to categorize and memorize, judgements about topics and objects and
solve problems in a way that’s fundamentally different than novices
- Expert knows how to solve new problems
o Has set of skills for solving new problems
o For ill formed problems, expert can find operators that apply to new problems
- Simply knows the answer to many similar problems
o Has lots of prior experience
o Need not start from scratch solving problems
o Bc solved similar problems in past; remember details of similar problems
Two systems
- System 1
o Fast
o Similarity based
o Emotion driven
o Primitive
Evidence this may by the experts system (experts better at 1, because fast and relies on
experience, once you store up enough experience you can use this fast similarity based
- System 2
o Slower
o Rule based
o Reasoning
o Evolutionarily more recent
- Experts may see world differently
- People must learn the relevant perceptual features in their domain
o Bird experts
Experts operate at subordinate level, Mevis and Rosch
- We said basic level category most operate at
o If you show variety of apple, they say apple not Granny Smith Apple
o Recall: experts operate at subordinate level
- When novices shown pictures of birds relate to birds as a group, or classify them as song birds or water
birds…basic level of categorization where experts able to name bird at subordinate level; prefer
- Lesgold
o Radiologists and med students examined X rays for 2 seconds longer
o Experts were better in 2 second condition
Knowledge used to fill in perceptual gaps
o Only in 2 second condition, when longer intermediate performed almost as well as experts
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- Perception limits the possibilities considered
o Too much info
o Generally a good thing
o Experts may miss novel features*
E.g. if tumor was in unusual location don’t show usual advantage
When in unknown domain expertise trails off
o Schema errors
- The way experts perceive a situation influences what they recall DeGroot; Chase and Simon
- Chess experts’ memory for real board positions better than novices
o But not for random positions; only if legal positions
- Novices can get about 5
Chi, Feltovich & Glaser (1st of the 3 studies 1981)
- Compared experts to novices (physics PhD students)
- Sort 24 physics problems into categories
o Look at underlying physical principles that helped them solve the problem (experts)
- Novices similar features
o Put them in surface or similar features
- Experts- major physics principle
o Deep understanding
o Said has to do with pattern matching
- First, Hinsely Hays and Simon found that college students can categorize algebra word problems into types,
and that this categorization can occur quickly
- Secondly, in chess research, it appears that experts’ superiority in memorizing chessboard positions arises
from existence of a large store of intact and well organized chess configurations or patterns in memory
- From research in medical diagnosis, there is evidence to suggest that expect diagnosticians represent
particular cases by general category and these categories facilitate the formation of hypotheses during
o All three of the studies suggest that experts rely on memory for patterns and prior cases
o In the main study (talk about first one) instructions sort 24 problems based on similarity of
Study one: Problem Solving
- Objective first study was to determine kinds of categories subjects of different experience pose on problems
- Instructions to sort 24 problems into groups based on similarities’ of solution could not actually solve
problems in order to solve them
o Just going to sort
o And then sort them again to make sure they are doing it properly
- Experts advanced PhD students
- Novices put them together based on similarity
o Tend to focus on how they look alike
- Compared to what experts do
o They don’t look alike on surface
- Fundamental insight about how expertise works
- When asked to elaborate on idea of inclined plane
o novice focuses of surface features; while expert has separate section of their elaboration
- differ in number of key features; experts list many more and focus again on solution of problem
o behaving in way fundamentally differ…expertise quickly understand conceptual importance of
problem and how it can be solved quickly understand it and put problems together on basis of
solution relevant feature not surface
Medin, Lynch and Coley
- Experiment 1: categorization of trees
- (1) One possibility is that all roads lead to Rome
o differing goals and concerns may not penetrate the compelling categorization that bio kinds afford
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