The initial segment strategy: A heuristic for route selection

People often choose one route when traveling from point A to point B and a different route when traveling from point B to point A. To explain these ro ute asymmetries, we propose that people rely on a heuristic (the initial se gment strategy, or ISS) during route planning. This heuristic involves basi ng decisions disproportionately on the straightness of the initial segments of the routes. Asymmetries arise because the characteristics that favor se lection of a particular route in one direction will usually differ from tho se that favor selection when traveling in the opposite direction. Results f rom five experiments supported these claims. In the first three experiments , we found that subjects' decisions were asymmetric and involved a preferen ce for initially straight routes. In Experiment 4, we confirmed that the IS S is a heuristic by demonstrating that people rely on it more when under ti me pressure. However, people can choose the optimal route when instructed t o do so. In Experiment 5, we generalized the findings by having subjects se lect routes on maps of college campuses. Taken together, the results indica te that the LSS can account for asymmetries in route choices on both real a nd artificial maps.