Spatial and movement-based heuristics for encoding pattern information through touch.

Seven experiments investigated the heuristics people use to encode spatial pattern information through touch. Observers traced a tangible pathway with one hand and then answered questions about either the euclidean line between the pathway endpoints or the pathway itself. Parameters of the euclidean line were held constant, while characteristics of the felt pathway were manipulated. Experiments 1-4 showed that blindfolded sighted and blind observers increasingly overestimated the length of the euclidean line as the length of the explored pathway increased. This indicates a movement-based heuristic for encoding distance. Experiments 5-7 indicated that judgments of the position of the euclidean line did not vary with the position of the felt pathway or the extent to which it deviated from that line. Instead, the results indicated that observers relied on implicit spatial axes, which are movement independent, to judge position. These and other results have implications for theories of haptic encoding of spatial pattern and for the construction of tangible graphics displays.