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Marcello Maniglia, Andrea Pavan, Yves Trotter; The spatial range of peripheral collinear facilitation. Journal of Vision 2015;15(12):327. doi: 10.1167/15.12.327.
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© ARVO (1962-2015); The Authors (2016-present)
In visual perception contextual influences on the detection of a target stimulus have been widely investigated. A striking number of studies have shown that detection thresholds for a central Gabor patch (target) can be modulated by the presence of co-oriented and collinear high contrast Gabor stimuli (flankers) with the same phase and spatial frequency. This phenomenon is thought to be mediated by lateral interactions between neurons’ receptive fields, and depending on the distance between the central target and flankers modulation can be facilitatory or suppressive. More specifically, collinear facilitation can be observed for target-to-flankers distances beyond two times the wavelength (λ) of the Gabor’s carrier, while for shorter distances (< 2λ) there is a suppressive effect. Collinear facilitation vanishes for target-to-flankers distances larger than 12λ. Recently, a series of studies showed the existence of such effects with stimuli presented at 4° of eccentricity, but only for larger target-to-flankers distances than in the fovea (>7λ). The aim of this study is to assess whether peripheral collinear facilitation extends beyond the limits of foveal presentation, shifting the peak of collinear facilitation towards higher target-to-flankers distances. We measured contrast detection thresholds for different spatial frequencies (1-6 cpd) and target-to-flankers distances (6-16λ), with configuration presented at 4° of eccentricity. Results showed that the range of collinear facilitation extends beyond 14λ for the higher spatial frequencies tested (4 and 6 cpd), while for the lowest spatial frequency (1cpd) it returns to baseline already at 10λ. One of the reasons for this reduced range of facilitation might be that for low spatial frequencies time integration window is a constrain for facilitation when flankers are too far away. Moreover, we found that the peak of collinear facilitation shifts towards larger target-to-flankers distances as the spatial frequency increases, a phenomenon never reported for peripheral or for foveal presentation.
Meeting abstract presented at VSS 2015
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