Navigating successfully from one place to another depends on combining information from multiple sources of spatial information. One important source is what we see, such as sidewalks, roads, and landmarks. Another important source is from our bodies: As we walk and turn, even with our eyes closed, we have a sense of how far we have traveled and which directions we are facing. These sources of information tell us where we are, where we are headed, and how hard it will be to get there (e.g., climbing a steep hill vs. walking around it). However, the information provided by these spatial cues may differ because of errors of memory or sensory-perceptual systems or because the cues indicate different locations in the environment. As the disparity between spatial cues increases, it is rational to conclude that the cues are indicating different locations not the same location. Navigators must estimate the likelihood that spatial cues indicate the same location or indicate different locations, and then decide how to choose an appropriate goal. The aim of the experiments proposed in this section is to investigate these inference and decision processes in spatial navigation.