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Maria Lev, Uri Polat; Filling-in in the periphery indicates that the collinear facilitation is similar to the fovea. Journal of Vision 2008;8(6):277. doi: 10.1167/8.6.277.
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© ARVO (1962-2015); The Authors (2016-present)
Collinear facilitation is a common phenomenon in the fovea, but it has been recently challenged in the human periphery. Using a new paradigm, Polat and Sagi (2007) have suggested that the feeling-in effect is induced by collinear facilitation in the fovea. Here, we used the same paradigm in the periphery to probe the facilitation using a Yes/No detection task by measuring the false-positive reports (false-alarm, Pfa) and hit-rate (Phit) for a low-contrast Gabor target (between two flankers) that appeared randomly in the fovea or at the periphery (2 deg) to the right or left side. We measured the facilitation effect in 3 experiments: 1) using different target-flanker separations, 2) comparing the collinear and orthogonal configurations and the target alone at 5λ, and 3) using different flanker orientations (0, 11, 22.5, 45, 90 deg.) at 5λ. The report for the target present was high (Phit, Pfa) for the collinear configuration and decreased with increasing target-flanker separation. The feeling-in effect for 5λ was similar to the results for 3λ in the fovea (Polat & Sagi, 2007). The sensitivity for the collinear configuration was significantly higher than the target and the orthogonal configurations for 5λ. The report for the target present was orientation specific; it was highest for the collinear configuration, but decreased with increasing differences in orientations between the target and flanker. However, the sensitivity of the collinear and the other configurations was similar, consistent with Polat & Sagi's results for mix-by-trial testing. The overall increase in the target-present responses only for the collinear configuration is consistent with excitatory interactions that induce filling-in in the periphery. The existence of a similar pattern of higher Phit and Pfa for the collinear configuration at the fovea and periphery suggests that collinear facilitation is a common phenomenon that exists in both the periphery and fovea.
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