Distance estimation from cognitive maps

Four experiments investigated map clutter as a source of distortion in distance estimates. In Experiments 1 and 2, subjects estimated distances between pairs of points on a memorized map. In Experiment 1, subjects learned relative distances among cities incidentally; in Experiment 2, they learned them intentionally. In both experiments, estimates increased as a linear function of the number of intervening points along the path. In Experiment 3, subjects estimated distances while viewing the map. The clutter effect was reduced but not eliminated. In Experiment 4, the clutter effect was demonstrated using subjects' pre-experimental knowledge of U.S. geography. Psychophysical power functions relating true to estimated distance provided a good fit to both memory and preception data. These results suggest in analogy between perceptual and memorial processes of distance estimation. The model providing the best fit to the data assumed that subjects perceptually scan a route from start to destination and use scan duration to determine path distance.