Classification images reveal observer templates underlying the direct tilt illusion

Spectral results for signal absent (SA) data, constructed by averaging fixated tiles that did not contain the target, are shown for the two observers (Fig. 3A). SA results contain the most compelling data since they are not affected by the additive influence of the target in the tile as displayed, and result purely from random perturbations of noise that resemble the target sufficiently well to cause the observer to make an erroneous visit, and potential erroneous acceptance of the tile as the search target.