Foundations Of Cognitive Science

Problem Behavior Graph

A problem behavior graph is a method used to analyze and depict the thought processes made explicit when a subject’s verbal protocol is collected while they think aloud as they solve a problem (Ericsson & Simon, 1984; Newell & Simon, 1972).  It is a collection of nodes that are linked together both horizontally and vertically.  A node makes explicit some state of knowledge about the problem, and is similar to an intermediate state of a problem space created by an AI researcher.  A horizontal node represents a particular operator that converts one state of knowledge to another.  A vertical node represents backtracking – when a subject reaches a dead end in reasoning, and goes back to some previous state of knowledge, this state is found in the problem behavior graph, copied, and inserted below the state.  Thus a vertical link connects two identical states of knowledge.  This also means that time spent working on the problem is reflected in both the horizontal and vertical dimension of the problem behavior graph.


  1. Ericsson, K. A., & Simon, H. A. (1984). Protocol Analysis: Verbal Reports As Data. Cambridge, MA: MIT Press
  2. Newell, A., & Simon, H. A. (1972). Human Problem Solving. Englewood Cliffs, NJ: Prentice-Hall.

(Added January 2010)