Final answer:
Finger waves are used to accentuate the face and help narrow a round head shape by creating horizontal lines that elongate the appearance of the face.
Step-by-step explanation:
The type of wave pattern used to accentuate the face and narrow a round head shape is finger waves. Finger waves are a method of setting hair into waves (curls) that was popular in the 1920s and 1930s and again in the late 1990s in North America and Europe. When styling, the wave pattern creates horizontal lines, which can make the face appear more elongated and thus help to give the illusion of a narrower head shape.
To create finger waves, you generally begin by applying styling product to damp hair, and then mold the hair into 'S' shaped waves with your fingers and a comb. The waves are typically formed close to the scalp, and in the direction that best frames the face. This method of styling can help to emphasize cheekbones and can visually elongate the face when done correctly.