Human Problem Solving: Sokoban Case Study

We describe a case study in human problem solving for a particular problem – a Sokoban puzzle. For the study we collected data using the Internet. In this way we were able to collect significantly larger data (2000 problems solved, 780 hours of problem solving activity) than in typical studies of human problem solving. Our analysis of collected data focuses on the issue of problem difficulty. We show that there are very large differences in difficulty of individual Sokoban problems and that these differences are not explained by previous research. To address this gap in understanding we describe an abstract computational model of human problem solving, a metric of a problem decomposition, and formalization of a state space bottleneck. We discuss how these concepts help us understand human problem solving activity and differences in problem difficulty.