Figure 4

(a) The stimulus figure prototype of Shepard and Metzler’s mental-rotation task and the schematic depiction of the AOIs. The two orthogonal arms (blue) are labelled Upper Arm, while the two parallel arms (orange) are labelled Lower Arm. The Upper Arm and Lower Arm of the left figure are defined as AOI-L1 and AOI-L2, respectively, while the Upper Arm and Lower Arm of the right figure as AOI-R1 and AOI-R2, respectively. (b) Schematic diagram of the experimental procedure. The key in the gray panel indicates the correct response, with ‘1’ indicating a matched stimuli pair and ‘2’ indicating a mirrored stimulus pair.