Thomas:

Mark is right.

Using the examples linked to as a reference, you no doubt understand that when the photographer took the photos, he/she had to stand at different distances from the subject in order to fill the frame with the head. As an example, he/she may have needed to stand 1 foot away when using the 24mm lens, 1.4 feet away with a 35mm lens, 2 feet away with a 50mm lens, etc. (example distances may be incorrect .

If the photographer then printed each example to lifesize, and put them side by side on a board, for you to look at, the perspective would look natural to you if you viewed each print from the same distance as the original shot was taken from.

You would need to view each one with one eye closed, and the relative size of the subject would decrease as you stepped farther and farther away, but the relationship of the size of the different parts of the subject's face to each other would appear natural in each case.

Binocular vision and the brain's ability to interpret differences without prompting tend to make the perspective distortions less obvious than they might be, but this approach does work.