Which person needs a bigger hat to fit his head? Of course, the fat person appears to have a bigger head than the thin person. This impression is especially pronounced if you look at the face rather than the head. Actually, both persons can wear a hat of exactly the same size because they are identical except the width of cheeks, jaws and necks. Importantly, this illusion is occurring in our daily life! Perception of a body part is influenced by other parts. Makeup, hairstyling, and clothing can take advantage of this kind of illusion to make you look better.