Micro expressions, as explained by Rana el Kaliouby, are real and represent subtle, fleeting facial expressions like an eye or lip twitch. These are often involuntary movements that occur when someone is lying, serving as a "leak" of their true emotions. With high-speed cameras, such expressions can be detected. Her company, Affectiva, developed technology capable of identifying these micro expressions, although they emphasize ethical use and have turned down offers for surveillance applications that didn't align with their values 1 .

For more, you can listen to the full discussion with Tim Ferriss and Rana el Kaliouby in the episode titled "AI, Emotional Intelligence, and The Journey of Finding Oneself" on the Tim Ferriss Show.