Abstract
In this study, we deal with the issue of searching for missing belongings that are used in our daily life. This study is regarded as a model case of a trial for integrating laboratory studies in cognitive psychology and understandings of human cognition and behavior in complex real situations. The search for missing belongings is experienced by everyone, and a typical problem solving behavior performed in a social context. We investigate this issue based on the framework of human problem solving, focusing on the similarity between the search process of missing belongings and the process of insight problem solving. We also try to explain why we feel serious difficulties in the search from a viewpoint of search for problem space. We explain the difficulties based on the dilemma existing between a depth-first search for a currently searching problem space and a shift of search to another problem space.
