Optometry and Visual Science, City University, London, UK
Search asymmetry is a litmus test for basic visual features. The letter Q is thought to contain a basic feature because i) it can be found quickly, no matter how many Os it is hiding amongst and ii) it is much harder to find an O amongst Qs. When two orthogonal Gabor patterns have the same spatial frequency, their sum can be found quickly, just like the letter Q. This sum is often called a plaid and it contains regions of both high and low Gaussian curvature, which are thought to automatically attract attention. I can now confirm that 4-cycle/degree Gabors do not pop-out from plaids of the same frequency. This result supports the notion that these plaids contain a basic visual feature. However, 2-cycle/degree Gabors do pop-out from 2-cycle/degree plaids. Do 2-cycle/degree Gabors contain a basic visual feature that is absent from 2-cycle/degree plaids?