Effects of Brightness Highlighting on Visual Search Performance within a Cockpit Display of Traffic Information

Abstract

This study investigated visual search of target aircraft on a Cockpit Display of Traffic Information (CDTI). Target aircraft were distinguished by an airspace course that conflicted with Ownship (the participant's aircraft). Of primary interest was the influence of brightness highlighting on participants' ability to detect the target aircraft among distractor aircraft. The display could present all (homogenous) bright aircraft, all (homogenous) dim aircraft, or mixed bright and dim aircraft, with the target aircraft being either bright or dim. In the mixed intensity display, participants were not instructed whether the target aircraft was bright or dim. The first experiment measuring participants' response time showed that instead of bright targets being detected faster, dim targets were detected more slowly in the mixed intensity display than in the homogenous display. The second experiment utilized Signal Detection methodology to determine the cause of this effect. The signal detectability measure, A'(a non-parametric variant of d'), revealed that targets presented at the dim intensity in the mixed intensity display yielded significantly lower sensitivity than either of the homogenous displays or the bright targets in the mixed intensity display. There was not a significant difference in False Alarm rates between any displays, indicating no change in decision criterion. Findings are discussed in terms of possible masking effects evoked by bright aircraft over the dim aircraft.