Is visual search more efficient in dynamic environments?

Most research into human visual-search behaviour has used static stimuli, or stimuli in which dynamic information differentiates targets from distractors, despite the fact that both the envi- ronment and its observers move. Subjects searched for a target Gabor patch, differentiated from the surrounding distractors solely by its carrier orientation, in three different types of array: static (stationary elements), jitter (oscillating elements), or dynamic (elements sequentially repositioned). Total orientation difference between target and distractors was varied between 5.78 and 22.68, as was the number of elements in the display, and presence or absence of target. Search efficiency was defined by the gradient of the function of reaction time against set size. In target-present displays, search was efficient for all three array types, even at the smallest orientation difference. In target-absent displays, search efficiency was unaffected by the degree of target/distractor simil- arity in the dynamic condition, but decreased with increasing target/distractor similarity in the jitter and static conditions. This suggests that the visual system is better equipped to locate objects in dynamic environments, in contrast to static ones, and hence that much of the existing visual-search literature may fail to characterise human behaviour in natural environments.