Fig 8. Symmetric variant of discrimination task engages two elementary operations with orthogonal preference.
The central probe was flanked by additional non-target templates (indicated by green in A). B-C plot overall (labelled ‘Human’) as well as target-present/absent PF’s for 2D and Θ conditions (similar plotting conventions to Fig 3B and 3D). F plots the overall 2D PF from the opponent variant of the LN model (left) and target-present/absent PF’s from the opponent variant of the gain congrol model (right; see Methods for detailed description of these variants). G plots overall Θ PF’s from these two models (magenta and yellow respectively) together with the human PF replotted from C (black). D plots target/non-target match values (similar to Fig 2F) from overall (black), target-present (red) and target-absent (blue) 2D PF’s; light colouring refers to the observer who had also participated in the original discrimination experiment without non-target templates. E plots peak/trough amplitudes of Θ PF’s (similar to Fig 2H) using similar colour-coding conventions. H plots normalized root-mean-square distance between simulated and human PF’s using the conventions adopted in Figs 5H and 5J and 6G and 6H. I plots outcome of 1st- and 2nd-order nonlinear tests using the conventions of Fig 3G and 3I across observers and noise masks from the original discrimination experiment (black) and its symmetric variant (green).