To the study of character pattern recognition by the automatic information processing system, psychologists can contribute in two ways at least. One is to analyse the human recognition process experimentally and to clarify its intrinsic nature, and the other is to offer some useful data about the ways to compose the optimal character patterns for the mechanical recognizers. Several years ago we showed one possibility of reasonably composing 46 Japanese Kata-Kana letters with 9×5 cells, and also ascertained that these quantized characters had tolerable readability as compared with typed letters.
The purpose of this paper is to describe quantitatively the features of each cell which is the minimum component of the quantized characters, and to clarify the process by which human
Ss recognize these characters when only part of the cell information was given. The Kata-Kana letters tentatively selected and used in this study were only 10 of all.
First, two corresponding cells
aij(
aij=1 or 0,
i=1......9,
j=1......5) of each pair of letters are compared, and if two cells are equivalent, that is, if both are either 1 or 0,
Yij is set to 0, while
Yij=1 if different. Since there are 45 pairs of letters, we get 45 sets of value of
Yij. Next, for each letter the sum
Zij is obtained by summing 9
Yij's in which the letter in question is paired with the other 9 letters (Table 2).
Zij's thus obtained show the degree to which the cells of that letter are structurally characterized with respect to the other letters. We can also sum up 45
Yij values of all pairs to obtain
Wij (Table 3).
Wij reflects the extent to which 10 letters are efficiently categorized into two groups according to the cell information. The cell with the maximum
Wij is the most important one in the sense that it would help the mechanical recognition system with maximum efficiency. Excluding all pairs that gave
Yij=1 in the most important cell and summing
Yij's for the remaining pairs, we obtain second set of values of
Wij, and determine the second important cell. Repeating these procedures until all pairs are exhausted, progressively less important cells are determined.
In experiment 10
Ss were asked to guess what the character was when partial information was given by one or more cells; in Exp. I only one cell with varing value of
Zij or
Wij was presented, and in Exp. II cells were presented one after another to accumulate information in the order of either computed importance (
F-condition), or randomness (
F′-condition). Based on the analysis of response distributions, the following were concluded.
1. When a cell with larger
Zij, was presented as a cue, the degree of correct identification was higher (Fig. 3), and the larger the
Wij value, the more the cell information character recognition. But the processing of information was not perfect and there seemed to be considerable loss of information.
2. The loss of information was less in
F′ which contained much useless information than
F which agreed with the theoretically efficient system, and increased as the possibility of correct identification became larger, especially in
F.
3. It was presumed that more than 25 cells or 16 bits of cell information have to be presented in order that
Ss can identify 10 letters perfectly.
4. It was also suggested that the redundancy of Kata-Kana letters quantized in 9×5 cells was slightly more than 0.7.
5. The efficient information that would help the mechanical system to recognize letters is not always efficient and important for the human
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