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Conclusions: It is possible and desirable to design a key that allows for clear, accurate recognition as a unit. This key, at the same time, will make a meaningful pattern when used with other keys. Keyboard display systems make possible rapid, accurate decisions in simple, direct control situations involving the assignment of columns to rows. Time for making simple, direct assignment decisions increases slowly with the number of elements in the keyboard. The largest size keyboards studied (120 keys) took less than 0.5 seconds longer to operate, on the average, than the smallest (36 keys). When columns are assigned to rows, increasing the number of columns does not affect time of operation as much as increasing the number of rows. Complex assignments on a keyboard display take much more time than do simple assignments. The amount of time required to solve assignment problems is proportional to the number of visual search operations required to hunt down the solution. (Author)