THE ENCODING-ERROR MODEL OF PATHWAY COMPLETION WITHOUT VISION

We present a model that accounts for errors in short-cutting to comple te a triangular pathway by individuals deprived of visual input. The m odel assumes that systematic error arises from components of navigatio n concerned with encoding an internal representation of the pathway, r ather than the computation of a homeward trajectory or motor output pe r se. Subjects' tendency to compress the range of actually produced tu rns and distances, in comparison to the range of correct values, is at tributed to regression toward the mean of encoded values during encodi ng of segments and turns, in the face of uncertainty about the actual values. Individual-subject variations are attributed to differences in the encoding-function parameters, not to variations in the processes themselves. The model provides excellent accounts of data obtained wit h triangular pathways but fares less well when pathway complexity incr eases, at which point errors do not appear to be solely attributable t o encoding processes. The sources of error identified by the model are likely to play a role in navigation more generally.