Another classification divides filling-in events into three main groups (Komatsu,
2006). The first group includes deficits of visual inputs when some region of the visual field is deprived of visual stimulation and the region is filled-in perceptually by the surroundings; the classical examples are the blind spot and scotomas. In both cases, several studies suggest that neural activity in V1 mediates this type of filling-in (Fiorani, Rosa, Gattas, & Rocha-Miranda,
1992; Matsumoto & Komatsu,
2005; Spillmann & Werner,
1996; Tong & Engel,
2001). The second group includes steady fixation and stabilized retinal images, such as Troxler's effect (Krauskopf,
1963; Troxler,
1804). Troxler's effect occurs when steady fixation causes a region in the periphery to be filled-in by its surroundings. Stabilization of the retinal image is the extreme case of this type of filling-in, using a device that eliminates movement of the retinal image caused by involuntary eye movements. In both cases, visual features in the surround occupy the part of the visual field corresponding to the object; neural activity in V1 is posited to mediate this filling-in (Hsieh & Tse,
2006,
2010; Mendola, Conner, Sharma, Bahekar, & Lemieux,
2006). The third group includes neon color spreading (Bressan, Mingolla, Spillmann, & Watanabe,
1997; Grossberg & Mingolla,
1985; Redies & Spillmann,
1981; van Lier,
2002; van Tuijl,
1975; Varin,
1971), the Craik–O'Brien–Cornsweet effect (Cornsweet,
1970; Craik,
1966; Grossberg & Todorovic,
1988), and the phantom illusion (Kitaoka, Gyoba, & Sakurai,
2006; Rosenbach,
1902; Tynan & Sekular,
1975). The third group essentially includes all the events that cannot be included in the first two groups. Recent studies show neural activity correlating with filling-in in V1 for neon color spreading and the phantom illusion (Meng, Remus, & Tong,
2005; Sasaki & Watanabe,
2004). For the Craik–O'Brien–Cornsweet effect, correlated responses have been found from LGN to higher level areas (Anderson, Dakin, & Rees,
2009; Boyaci, Fang, Murray, & Kersten,
2007; Cornelissen, Wade, Vladusich, Dougherty, & Wandell,
2006; De Weerd, Gattass, Desimone, & Ungerleider,
1995; Perna, Tosetti, Montanaro, & Morrone,
2005; Rossi & Paradiso,
1996; for review: Hsieh & Tse,
2010; Komatsu,
2006; Paradiso et al.,
2006; Pessoa et al.,
1998; Spillmann,
2009b).