The effects of display failures, polarity, and clutter on visual search for symbols on cartographic images

Abstract

Little research has been conducted dealing with human performance in symbol search of cartographic images on matrix-addressable displays. Alphanumeric studies have researched failures and polarity on such displays, but not using cartographic images. Two studies were conducted which required the subject to search for symbols on cartographic images under various conditions of failure, polarity, and background clutter. Response time and accuracy were measured. Generally, high clutter impeded performance more than low clutter, and negative polarity produced slightly better performance than positive. Horizontal line failures affected search ability more than vertical line or cell failures, particularly when the failures were in "on" mode rather than "off" mode. Further, it was found that while previous alphanumeric studies found effects at three percent failures or greater, effects were observed for the present studies at two percent or greater, apparently due to the presence of map information on the display. Recommendations for cartographic display design and future research are discussed.