Number Of Different Symbols Research Articles

Perceptual chunking of symbols in memory span

Memory span for strings nine symbols in length ranging from two through nine different symbols per string was examined with repeated measures. Strings were sequentially exposed on a memory drum for 3 sec each; subjects recorded recall when the exposure interval elapsed. Memory span of symbol strings decreased as the number of different symbols composing the strings increased. Amount remembered was also a function of mode of output. Errors in recall indicated that perceptual overlap of symbol features was responsible for confusion errors. When symbols were rotated, confusions became within-symbol rather than between-symbol errors; between-symbol chunking was disrupted by loading individual symbol channels with within-symbol information. Systematic between-symbol chunking suggested that perceptual chunks are formed prior to output; error data revealed a distinct weakening of between-symbol associations when subjects had within-symbol priming information during output.

Memory span: Effects of symbol orientation

Memory span for symbol strings was tested in a repeated measures design. Strings were nine symbols in length, with varying compositions (two to nine different symbols per string). Condition C had symbols in constant conventional orientation, Condition A, in constant altered orientation, and Condition V, variably in all 90-deg orientations. Memory span decreased as number of different symbols composing strings increased. Errors in recall showed that perceptual overlap of symbol features accounted for confusion. When symbols were rotated (V), confusions became within-symbol rather than between-symbol; if orientation was ignored in V and identity and position became the criteria for correctness, errors decreased even though symbols increased, and errors were due less systematically to perceptual mechanisms. Rotation disrupted between-symbol chunking.

Design factors in the development of an optical character recognition machine

Interest in optical character recognition has grown tremendously during the past several years. When one considers the volume of printed information that must be accessible both to human readers and to data processing machines, the increasing interest is not at all surprising. Many optical character recognition principles that appear to be quite powerful are impractical or too costly to implement with available technology. Other principles that appear relatively economical require an input quality that is impractical to generate. The field for commercial development falls somewhere between these two extremes. Many factors determine the character recognition principles to be utilized in the development of a machine system. Of primary importance are: 1) The shapes of the symbols to be sensed, 2) The number of different symbols to be discriminated, 3) The print quality range that must be accommodated, and 4) The required performance of the system. Unfortunately, in the present state of the art, the relationship of these factors to each other and to a given principle can be only qualitatively defined. This paper describes and discusses the development of a practical optical character recognition system, the character recognition portion of the IBM 1418 Optical Character Reader. The considerations involved are applicable to the development of any character recognition system.