PSYCH 240 Lecture Notes - Lecture 19: Representativeness Heuristic, Functional Fixedness, Power Law
Psych 240 Lecture 19: Problem Solving
Lecture Outline
Issues:
(a) Representing problems
(b) Methods and common flaws in problem solving
(c) Expertise
3. Problem solving methods
a. Algorithms and heuristics
b. Heuristics: hill climbing, means-ends analysis, working backward
4. Expertise
a. Very domain specific
b. Power law of practice
c. Characteristics of expertise
Means-end anaylsis
• Try to figure out how far you are from the goal
• Find the biggest difference between where you are and the goal
• Try to eliminate this difference using operators
• Continue to do this under you reach you final goal
Productions for Tower of Hanoi
• If the peg 3 is clear and the largest disk is free, then move the largest disk to peg 3
• If the largest disk is not free, then set a subgoal to free it
• If a subgoal is free the largest disk and a smaller disk on it, then move the smaller disk off
• Can turn these into productions rules
o Can also solve cognitive problems this way
Problem-Solving: Working Backward
• Transform goal state so it is more similar to the initial state
• Useful if too many paths can lead to the same goal
o i.e. mazes
o i.e. geometry proofs
• Water Lilies Problem
Expertise
• Expertise usually helps ability to solve problems
o More experience
o Better representation
o More practice solving problems
• But, can sometimes harm
o Functional fixedness
Document Summary
Issues: (a) representing problems (b) methods and common flaws in problem solving (c) expertise: problem solving methods, algorithms and heuristics, heuristics: hill climbing, means-ends analysis, working backward, expertise, very domain specific, power law of practice, characteristics of expertise. Productions for tower of hanoi: can turn these into productions rules. If the peg 3 is clear and the largest disk is free, then move the largest disk to peg 3. If the largest disk is not free, then set a subgoal to free it. If a subgoal is free the largest disk and a smaller disk on it, then move the smaller disk off: can also solve cognitive problems this way. Kinds of reasoning: deterministic: deductive, general to specific, deductive reasoning is guaranteed to give you the right solution if starting info is true, probabilistic: inductive, specific to general, deductive, theory, hypothesis, observation, confirmation/falsification. Inductive: observation, pattern, hypothesis, theory, does not have to be true.
