Example of the stimuli used in Studies 2B and 2C with corresponding Fourier slope in parentheses.

<p>Face images (from the FACES database [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0122801#pone.0122801.ref059" target="_blank">59</a>]) with manipulated slopes of the radially averaged log-log Fourier power spectrum. A: Stimuli used in Study 2B. B: Stimuli used in Study 2C. Note that the subjective impression of each image changes with size and viewing distance, and that the images with shallower slopes become more blurry at this resolution due to the reduction of power in the low spatial frequencies. Images of original size are provided as supplemental material (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0122801#pone.0122801.s002" target="_blank">S2 Fig</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0122801#pone.0122801.s003" target="_blank">S3 Fig</a>).