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Problem Solving,
Reasoning, & Judgment
PSY 2012
Claudia Stanny
Problem Solving
• Problem Space
 Initial state
 Goal state
 Operations
• Well-defined Problems
 Can be solved using algorithms
 Initial state, goal state, and operations can be clearly
identified
• Ill-defined Problems
 Initial state, goal state or operations are ambiguous. Not
always clean when the problem is solved.
Algorithms
• Step-by-step process
• Following the steps will always produce a
solution to the problem
Ordering a set of books alphabetically
Solving an arithmetic problem
• Used with well-defined problems
Heuristics
• Cognitive “short cuts” or “rules of thumb”
• Suggest a possible solution to a problem
quickly
• May not always generate the best answer to
the problem
 availability heuristic
 representativeness heuristic
• Used for ill-defined problems
How to study problem solving?
• Think-aloud protocols
 Problem: John has 6 marbles. Paul has twice as
many marbles as John. Phil has 3 marbles fewer
than John and Paul combined. How many
marbles does Phil have?
 Describe what you think about as you solve the
problem
• Describe how you organize the problem
• Describe the steps you follow to solve the problem
Improving Problem Solving
• Find the correct representation of the problem
 Within knowledge domains, expert problem
solvers learn about types of problems and how
best to represent each type
• Practice operations used to solve problems within a
domain
 Ability to rapidly carry out problem-solving
operations allow experts to rapidly reason
forward from current knowledge
 Novices tend to use more time-consuming
backward reasoning strategies
Functional Fixedness
• Explain the rule that determines the order of
each of the following sets of ten numbers:
 2 4 6 8 10 12 14 16 18 20
 1 1 2 3 5 8 13 21 34 55
 8 5 4 9 1 7 6 3 2 0
Reasoning
• Drawing logical conclusions from assumptions
or other prior information
• Correctly apply the rules of logic to arrive at
valid conclusions
 All apples are fruit.
 This is an apple.
 This is a fruit.
Belief-Bias Effect
• We tend to judge the validity of arguments based on
the truth of the conclusion rather than on the validity
of the logic used.
• Invalid use of logic sometimes produces conclusions
that are true.
 If my finger is cut, then it bleeds. My finger is
bleeding. Therefore, my finger is cut.
(Invalid but true)
 If I eat candy often, then I have cavities. I have
cavities. Therefore, I eat candy often.
(Invalid and not true)
Judgment & Decision Making
• Choices made with ill-defined problems
• No established, correct rules for making these
choices
• No clear method for determining whether we
have made the correct decision
 Which of two apartments should you rent when
the choices vary in cost, location, size, age of
appliances, etc.?
Heuristics & Biases in Judgment
• Heuristics
 rules of thumb or other short cuts that usually
produce good solutions
 attractive because they allow us to arrive at
decision quickly
 create problems because they do not guarantee
that the solution will be correct
Which set of letters (A or B) will
allow us to draw the largest number
of different paths? X X
A
X X X X X X X
X
X X X X X X X
X
X X X X X X X
X
X X
B
X X
X X
X X
X X
X X
X X
X X
Availability Heuristic
• Decisions made based on the most readily available
information
• Decisions made on information accessed quickly
rather than on all of the relevant information
• Memory processes can provide a biased sample of
examples or biased information
 which event is the more likely cause of death in the US?
• Falling airplane parts
• Tornado
• Car accident
Shark attack
Lightning
Pneumonia
Representativeness Heuristic
• Which of the following sequences of letters
was most like to have been created by a
random process (such as flipping a coin)?
XOXXXOOOOOXXOOOXXXXOX
XOXOXOOOXXOXOXOOXXXOX
Anchoring Heuristic
• If all of the human blood in the world were
poured into a cube-shaped tank, how wide
would the tank be?
Framing Effects
• Representation (frame) of the problem can
influence the decision made.
Which lottery would you choose?
• Ticket has a sure win of $250.
• Ticket has a 25% chance to win $1000 and a 75%
chance to win nothing.
 Which lottery would you choose?
• Ticket has a sure loss of $750.
• Ticket has a 75% chance to lose $1000 and a 25%
chance to lose nothing.
Decision Aversion
• Situations in which people try to avoid making
any decision at all.
 Decisions that will result in gains for some and
losses for others
 Decisions in which the person fears that they will
regret their choice
 Decisions in which the person will be held
responsible for bad outcomes
 Decisions made on behalf of other people