Positive and negative hysteresis effects for the perception of geometric and emotional ambiguities - Fig 4

Gray-scale version (S9) of Da Vinci’s original Mona Lisa painting (left) and a magnified excerpt of the mouth region (right). Left: The five orange circles indicate the locations at which luminance was measured. Right: The blue arrows indicate the trajectories of the mouth corner locations of the sadder stimulus variants used in the present experiment. The blue filled circles indicate the left and right mouth corners of the central Mona Lisa S5 variant in the middle of the stimulus range.