People focus too much on mouth movement, but humans actually notice eye behavior first. I tested dozens of AI presenter videos and viewers tolerated imperfect lip sync if blinking and head motion looked natural. But perfectly synced lips with dead eyes still triggered the “uncanny valley” effect. Newer systems from HeyGen improved this a lot with gesture modeling and expression tracking.

100% true. I reduced eye contact intensity slightly and my audience retention improved. Constant staring into the camera looks creepy after 15 seconds. Background music helps hide tiny sync issues too. Dead silence makes viewers analyze every mouth movement subconsciously.One overlooked issue is frame rate mismatch. If your exported avatar is 24fps but your editor timeline is 60fps, motion interpolation can create weird mouth artifacts.

I think AI creators should study real interview footage more. Humans constantly move slightly while speaking. Tiny shoulder movement and breathing make digital avatars believable.