Figure 1. Procedure of a trial in the A-DecNef training stage.
An achromatic (gray-black) vertical grating was presented during the induction period (6 sec), during which participants were trained to induce BOLD-signal multi-voxel patterns in V1/V2 corresponding to the color red, unbeknownst to participants. Immediately after the fixation period (7 sec), a feedback disk was presented for 1 sec. The disk size roughly represented how similar the BOLD-signal patterns in V1/V2 induced during the induction period were to the patterns evoked by the target color stimuli (red-black gratings) presented in the color classifier construction stage. See also Figure S1.