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Historically, visual search experiments used artificial stimul i (simple shapes) as targets an d distractors arranged in an imaginary array of cells on a blank background. Little resear ch on search behavior has been conducted with naturalistic stimuli and a frequency-domain framework. With the common metric provided by Fourier analysis, it is possible to compare the effects of various frequency-domain components on search efficiency. 1 In the current study, we experimentally manipulated the spectral content of target an d distractor (background) cells filled with spatially filtered segments of real-life scenes. Our experimental design incl uded two types of spatial filters, orientation (some frequency overlap between target and distractor) and spatial frequency (no overlap), and uniform distractor (target and distractors filtered similarly) and mixed distractor (only half distract ors filtered like the target) conditions. Generally, observers found the target more quickly and were more confident in their performance in the mixed condition. Observers were faster, more accurate, and more confident in the spatial filter condition than in th e orientation filter condition. Overall, observers spent less time (fixation duration) and effort (fixation frequency) examining dissimilar distractors. The effect with the fixation frequency measure was magnified when the spatial frequency filter was used. Keywords: visual search, eye fixations, naturalistic images , spatial filter, frequency-domain framework, visual analyzers |
