1 Problem Solving We view many situations in life as problems we need to solve Also, much of human behavior can be considered problem solving, even if we don’t think of it as such Herb Simon provided a theoretical framework for understanding how humans solve problems

2 What is a Problem? Situation in which we have a goal But the situation starts out being different from the goal Some obstacle prevents you from just converting the situation from the start state to the goal state

3 What Can Be Learned? How important our internal mental representations are in influencing our behavior Problem representation isn’t out there in the world, it’s in the problem solver’s head The success of our behavior depends on the nature of the representation

4 Start State Goal State Missionaries and Cannibals

5 Problem Solving Herb Simon’s Framework Elements States - Start and Goal Operators - Ways to change the state Intermediate states Constraints Problem space

6 Problem Space Start State (none on right) Goal State (all on right) Intermediate States 1 on right 2 on right 3 on right 4 on right5 on right

7 Constraints First - Must use a boat to cross the river Can’t hold more than two Must have at least one to row the boat Second - Must never allow Cannibals to outnumber Missionaries

8 Constraints Start State (none on right) Goal State (all on right) Intermediate States 1 on right 2 on right 3 on right 4 on right5 on right

9 Solution? Start State (none on right) Goal State (all on right) Intermediate States 1 on right 2 on right 3 on right 4 on right5 on right 1 1

10 Missionaries and Cannibals Start State (none on right) Goal State (all on right) Intermediate States 1 on right 2 on right 3 on right 4 on right5 on right A B B2 C C2 D D2 E

11 Start State Move 1 Move 2 State 1 State 2 Move 3 State 3 Move 4 State 4 Move 5State 5Move 6State 6Move 7State 7Move 8 State 8 Move 9State 9 Move 10 Move 11 State 10 Goal State Missionaries and Cannibals

12 What have we learned about problem solving? Framework Strategies An expert would have to represent problems differently than a novice

13 Experts vs. Novices Represent problem in terms of principles Possesses lots of domain specific knowledge Spend more time forming their representation Then work forward, rather than using weak methods

14 The problem space is in the problem solver’s head Our representation of the real world is in our head How a problem is represented influences our success as solving it How we represent the world influences the success of our behavior What have we learned about human behavior generally?