Application of geometric models to letter recognition: Distance and density

Reviews studies in which a single letter was visually presented under adverse conditions and the S's task was to identify the letter. The typical results for such studies were that (a) certain pairs of letters were more often confused than other pairs of letters; (b) certain letters were more easily recognized than others; and (c) confusion errors for a letter pair were often asymmetric, the number of errors differing depending on which letter of the pair was presented as the stimulus. A geometric model incorporating the properties of distance and spatial density is presented to account for these results. The present application of the distance-density model assumes that each letter is constructed in a typical 5 × 7 dot matrix. According to the model, (a) pairs of letters that are in close geometric space are more often confused than pairs of letters that are distant; (b) letters that are in less spatially dense regions are more easily recognized than letters that are in more spatially dense regions; and (c) asymmetric confusion errors result when one member of a letter pair is in a denser region than the other member of the letter pair. (59 ref)