Effect of the Size of a Complex Display upon Visual Search*

This investigation is one of a series of studies designed to determine natural search tendencies during visual search tasks. In this study twelve subjects were presented an ordered series of experimental aerial maps of different size. Their eye traces were recorded on a modified ophthalmograph while they searched for a specific critical detail. As was noted in other experiments of this series, coverage of the display was not uniform. In particular, greatest attention was paid to the center of the display. Search behavior in displays subtending 9° and larger at the eye remained essentially the same. For smaller displays, marked differences were noted. As the size of the display decreased, durations of fixation increased, interfixation distances decreased, concentration of attention in the central area increased, and efficiency decreased. Efficiency is defined as percent of eye fixations falling within the display area. The implications of these findings are discussed.