Fig 3. Significance maps [top (at rest) and second from the bottom (at peak of smiling)] and difference maps [younger minus older; second from the top (at rest) and bottom (at peak of smiling)].

For the significance maps, blue designates P ≤ 0.05; pale pink, P ≤ 0.01; dark pink, P ≤ 0.001; and purple, P ≤ 0.0001. For the difference maps, red indicates that the younger group exhibited greater values than the older group, whereas blue indicates that the older group exhibited greater values than the younger group. Differences are represented in mm.