Why most people can lift their left eyebrow but not their right?

Wisconsin psychologist Karl Smith found that people can be categorized based on which side of their face is dominant. Around 85% are right-faced while only about 15% are left-faced. This distribution is consistent to that of left-handedness.

In his research, he measured facial dominance by observing facial muscle responses. He found that the dominant side of the face is usually larger, more muscular, more flexible during speech, and may feature a deeper dimple when smiling. This dominant side often appears more expressive with a higher brow and a tendency to tilt toward the listener during conversation. The mouth also opens wider on the dominant side when speaking.

Smith noted that although most people are right-faced, musicians and performers in genetal are more often left-faced. This may reflect a more developed right hemisphere of the brain, which plays a major role in musical and emotional processing. By contrast, individuals such as mathematicians, scientists, athletes, politicians, newscasters, and actors are more likely to be right-faced. Smith suggests this is because they rely more on analytical thinking and speech, both of which are functions associated with the left side of the brain.

People Are Literally Two-Faced

If you take a photo of someone and draw a line down the center of their face, the two sides will often appear different. The left side of the face is naturally more expressive.

In fact, when actors portray emotions, viewers tend to identify those emotions more easily in the left half of the face. This is likely because the right hemisphere of the brain, which is responsible for emotional processing, controls the muscles on the left side of the face. Meanwhile, the left hemisphere, which controls the right side of the face is more analytical and less emotionally expressive.