“…After training, we observed a significant contraction in the perceived distance between the training locations, with the degree of contraction dependent on the training separation (repeated-measures ANOVA; effect of training on perceived distance: F (1,29) = 41.473, p < 10 −6 ; quadratic trend in interaction between training effect and training separation: F (1,29) = 7.632, p = 0.010. The contraction was maximal at a training separation of 4.4 degrees, which corresponds to a cortical separation of 12 mm in human V1 ( Schira et al, 2007 ) and falls within the extent of V1 lateral connections ( Ringo, 1991 ; Burkhalter et al, 1993 ; Kaas, 2000 ; Levitt and Lund, 2002 ; Voges, et al, 2010 ; Ahmed et al, 2012 ; Lyon et al, 2014 ). Because of the mirror-symmetry of human retinotopic organization, V1 is the only early visual cortical region whose ventral part (representation of upper visual field) and dorsal part (representation of lower visual field) are contiguous, whereas the ventral and dorsal parts of other early visual cortical regions (e.g., V2, V3) are segregated by V1 ( Sereno et al, 1995 ; Brewer and Barton, 2012 ; Wang et al, 2014 ).…”