The effects of extended practice on the evaluation of visual display codes

Abstract

A series of nine experiments is reported in which highly practiced subjects were used to investigate the use of letters, digits, familiar geometric shapes, and colored dots as coding dimensions in visual displays. These experiments used single-code and dual-code displays in three isolated tasks (choice reaction, search and locate, and identification-memory) and in a multiple task that combined the three tasks in an irregularly alternating sequence. The results of these experiments provided no basis for concluding that any particular code has a general advantage or disadvantage over any other. Furthermore, when there were differences in performance with different codes, there was a tendency for practice to attenuate those differences. It is concluded that the relative effectiveness of different visual codes varies as a function of practice, other display conditions, the tasks, and the dependent measure used to make the comparison.