Abstract
Visual search in the real world is complex and can involve high numbers of static and moving elements, some of which also change in luminance or disappear over time. To date, most visual search tasks have not examined the impact of these simultaneous, dynamic effects on search performance. We investigated how participants search a complex environment in the laboratory by designing a Multi-element Asynchronous Dynamic (MAD) visual search task which has (a) a high set size, (b) moving and static stimuli, (c) stimuli that change their luminance over time (by gradually blinking on and off) and (d) target uncertainty (e.g., the target was one of five possible letters, could be in any of moving or blinking groups and was absent on a subset of trials). Experiments 1 and 2 found that under these complex, MAD conditions search for moving items was less efficient than search for static items; however there was no effect of luminance change. Participants also missed a high percentage of the targets. In Experiment 3, participants knew in advance whether the target would be moving and/or blinking. Even with this advanced knowledge, search for moving targets was less efficient than search for static targets and there was no effect of luminance change. Finally, Experiment 4 replicated MAD search using smaller set sizes. Now search through moving and static items was equivalent, there was no effect of luminance change and error rates were reduced. Overall, the data show that increasing the complexity of the display drastically changes the way people perform a search task.