Visual search controlled by spatial frequency without salient features in an image

To clarify the characteristics of visual search that are controlled by spatial frequency, we measured the scan path during eye movement in response to visual stimuli. A target stimulus with the spatial frequency of 1/ f β (where β is the slope of power spectral density of luminance in an image) was embedded in a background stimulus with white (1/ f 0 ) characteristics. An instruction‐based task was employed in this study, wherein a subject searches for the target as rapidly as possible and fixates on it. Participants were six healthy males aged 21–22 years. In the task, a threshold for spatial frequency that was the minimum value required by the subjects for the search corresponded to β =∼ 0.2 − 0.3. This finding has potential application in the design of visual presentation media, such as signs and tablets, by providing ease of viewing to the user. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.