Mechanisms underlying global stereopsis in fovea and periphery

Abstract

To better understand the pooling properties underlying global stereopsis we examined the relationship between carrier luminance spatial frequency and modulator disparity spatial frequency. Thresholds for detecting global sinusoidal disparity corrugations of spatially band-pass noise were measured as a function of modulator disparity spatial frequency for both centrally and peripherally located stimuli using a standard 2-IFC task. We found a characteristic relationship that depended on modulator disparity spatial frequency. At high modulator disparity spatial frequencies (>1c/d), there is an optimal ratio of around 2.6, whereas at low modulator disparity spatial frequencies, there is an optimal absolute carrier luminance spatial frequency (i.e., 3c/d). In the periphery, vision is restricted to modulator disparity spatial frequencies below 1c/d and, as a consequence, following the above rule, there is an optimum absolute carrier luminance spatial frequency that reduces in spatial frequency with increasing eccentricity. This finding is consistent with there being more than one channel processing global stereo that is subsequently confirmed using a 2×2 AFC detection/discrimination paradigm. Furthermore, because of the different carrier/modulator relationships in central and peripheral vision, peripheral global stereo cannot be simply related to central global stereo by a scaling factor and thus cannot be simply due to cortical magnification, as originally thought.

Representation of central and peripheral vision in the primate cerebral cortex: Insights from studies of the marmoset brain

“…The scope of this paper has been limited to spatiotemporal aspects of vision for which relevant data have been obtained in the marmoset, and therefore it does not cover important issues such as colour perception (Martin et al, 2001), stereopsis (Witz and Hess, 2013), attention (Roberts et al, 2007), object recognition (Strasburger et al, 1994), and shape analysis (Whitaker et al, 1993). The following are some directions that we think might be fruitful for future research.…”

Characterization of Spatial Frequency Channels Underlying Disparity Sensitivity by Factor Analysis of Population Data

“…For instance, it could be used to tune the different layers of multi-scale algorithms (Rohaly and Wilson, 1993) or provide fine and coarse scales for algorithms processing in center and periphery, respectively, as stereopsis could be mediated by different mechanisms in central and peripheral vision (Wardle et al, 2012; Witz and Hess, 2013). …”

Similar Mechanisms Underlie the Detection of Horizontal and Vertical Disparity Corrugations

“…Indeed it has been suggested that the underlying mechanisms subserving the detection of horizontal and vertical disparity corrugations might be different; there being multiple channels for horizontal disparity corrugations but only a single channel for vertical corrugations [7]. Having previously established the optimal conditions for measuring sensitivity for vertical corrugations [1], we are in a good position to compare it to the sensitivity for detecting horizontal corrugations. We first set out to see if the same rules applied to the detection of horizontal corrugations as we had previously found for the detection of vertical corrugations; namely the carrier/modulator dependence.…”

“…Recently, we showed that there is a relationship between carrier spatial frequency and disparity corrugation spatial frequency [1]. Optimum disparity sensitivity occurs at low disparity corrugation spatial frequencies (<1 c/d) when the carrier spatial frequency is fixed at around 3 c/d.…”

“…When both of these requirements are met, the shape of the sensitivity function does not radically change, retaining its characteristic band-pass shape. [1].…”