Flicker haloes observed with subjective borders.
Subjective borders are known to behave quite similarly to real borders when the stimulus presents fragments of visually meaningful forms. There is less information on whether this also applies to unfamiliar stimulus elements. Thus, if a dark/bright stimulus border is presented intermittently at certain frequencies below flicker fusion, the bright border enhancement band increases greatly in width and takes on a textured appearance, resembling a halo streaming from the border. The percept is spontaneous and unlike anything experienced in real life. Preliminary observations showed that the effect occurs also at subjective borders. The extent of the halo from the border was measured for various flicker frequencies and compared with similar measurements obtained with real borders. It was found that the extent varies with frequency in an identical manner for real and virtual borders. Also, the halo was judged equal in qualitative appearance for both kinds of border. The striking similarity between virtual and real effects in this respect is best explained in terms of physiological border perception processes, possibly instigated by a cognitive mechanism.
D000328:Adult; D003071:Cognition; D005403:Fixation, Ocular; D005425:Flicker Fusion; D005556:Form Perception / Q000502:physiology; D006801:Humans; D007088:Illusions / Q000502:physiology; D008029:Lighting; D009903:Optical Illusions / Q000502:physiology; D012160:Retina / Q000502:physiology