Concentric orientation summation in human form vision

Abstract

Psychophysical data demonstrate that orientation information in concentric, random-dot Glass patterns is summed linearly to extract a global form percept. Surprisingly, no such global pooling was found for Glass patterns with parallel structure. A simple neural model explains these results and agrees with recent V4 single unit physiology. As V4 provides the major input to IT, global concentric units may play an important role in analyzing complex images such as faces. In support of this possibility, deficits in the perception of concentric Glass patterns have recently been linked to prosopagnosia.

Sensibilidade ao contraste de freqüências radiais em crianças de 4 a 7 anos e adultos

“…H. Kelly & Magnuski, 1975). Além disto, estudos psicofísicos Santos et al, 2004;Wilson, Wilkinson & Asaad, 1997;Wilson & Wilkinson, 1998) e neurofisiológicos (Gallant, Connor, Rakshit, Lewis & van Essen, 1996;Heywood, Gadotti & Cowey, 1992;Merigan, 1996;Wilkinson et al, 2000) sugerem que estímulos visuais do tipo grade senoidal em coordenadas cartesianas são processados na área visual V1 (córtex visual primá-rio) e que padrões radiais em coordenadas polares são processados por áreas visuais extra-estriados V4 e córtex ínfero-temporal (IT).…”

Differential human brain activation by vertical and horizontal global visual textures

“…Neurons in V3A have relatively large receptive Welds and contain a complete, contiguous representation of the visual Weld, making them potentially well-suited for an involvement in form integration. Previous studies suggested that concentric structure is processed by diVerent mechanisms than is parallel structure (Wilson et al 1997;Wilson and Wilkinson 1998;Wilkinson et al 2000;Kurki and Saarinen 2004), in particular, for concentric stimuli, the local orientation information is combined over larger spatial extents (Wilson et al 1997;Aspell et al 2006). Given this, it is likely that concentric structure would be eYciently processed by neurons with large receptive Welds, such as those in V3A.…”

“…Many psychophysical studies (Maloney et al 1987;Dakin 1997aDakin , b, 1999Wilson et al 1997;Wilkinson 1998, 2003;Kurki and Saarinen 2004;Lewis et al 2004;Aspell et al 2006;Bell et al 2007) have investigated the mechanisms that mediate the integration of local features into global forms, and some have provided evidence for diVerent mechanisms underlying the detection of concentric and parallel structure. These studies have used stimuli-Glass patterns, Gabor or simple line element displays-that generate the perception of a global form when their constituent elements (oriented dot pairs or Gabor/line elements) are organized as global conWgurations.…”

“…Coherence thresholds for detecting concentric structure have been reported to be lower than those for detecting parallel structure (Dakin 1997a(Dakin , 1999Wilson et al 1997;Wilkinson 1998, 2003;Kurki and Saarinen 2004;Lewis et al 2004). There is also evidence that the processing of concentric and parallel structure requires diVerent degrees of spatial integration (Wilson et al 1997;Wilson and Wilkinson 1998;Braddick et al 1999).…”

“…There is also evidence that the processing of concentric and parallel structure requires diVerent degrees of spatial integration (Wilson et al 1997;Wilson and Wilkinson 1998;Braddick et al 1999). However, our research has recently shown a spatio-temporal interaction in the processing of these forms that leads to optimal sensitivity occurring for diVerent combinations of stimulus duration and spatial extent for these two types of global forms (Aspell et al 2006).…”