An intriguing and ubiquitous phenomenon in vision is the perception of spatial property information (e.g. separation, size, shape etc.) that departs from the raw physical inputs yet conforms to the visual context. While it has been postulated that visual system employs an internal adaptable metric by which the signals conveying the spatial property information are scaled, it remains unknown whether and how such putative visual metric is represented in the brain. Here, we hypothesized the putative visual metric is mediated by the joint responses of differently-tuned spatial frequency (SF) channels, and investigated this idea by combining the use of psychophysics, fMRI-based population receptive field (pRF) mapping and computation modeling. We found that reweighting of spatial frequency (SF) channels, either by adaption or presentation of the corresponding SF background, led to systematic distortions of the perceived spatial property information. Moreover, the pRFs in V1 were more concentrated towards the fovea under the high SF stimulation regardless of their positions in the visual field. Importantly, both the perceptual distortions and the global-scale pRF displacement were functionally coupled with the changes in the population SF response induced by SF channel reweighting. Our findings revealed, for the first time, the neural apparatus signaling the putative visual metric that constrains spatial vision by establishing the comprehensive three-way connection between SF channel reweighting, pRF position displacement and perceptual distortions of spatial property information.
