%0 Journal Article %A Christina Moutsiana %A Benjamin de Haas %A Andriani Papageorgiou %A Jelle A. van Dijk %A Annika Balraj %A John A. Greenwood %A D. Samuel Schwarzkopf %T Cortical idiosyncrasies predict the subjective experience of object size %D 2015 %R 10.1101/026989 %J bioRxiv %P 026989 %X Perception is subjective. Even basic judgments, like those of visual object size, vary substantially between observers and also across the visual field within the same observer. How the visual system determines the size of objects remains unclear. We hypothesize that size is inferred directly from stimulus representations in V1 and predict that idiosyncrasies in cortical architecture should explain individual differences in size judgments. Indeed, using novel behavioral methods we demonstrate that biases in size perception are related to both the spatial tuning of neuronal populations and local cortical magnification in V1, as measured with functional magnetic resonance imaging in healthy volunteers. Our results indicate that the visual system infers size from V1 representations and that individual perception of even simple stimuli is warped by idiosyncrasies in brain organization. %U https://www.biorxiv.org/content/biorxiv/early/2015/09/16/026989.full.pdf