Why do narcissists, sociopaths, and psychopaths have dead eyes?

This dead-eyed thing is a pile of horse shit.

This is photojournalism. The images circulated with "dead" eyes are what people want you to believe. You want to believe it, so you believe it. Capturing a snapshot of a person's face, and more specifically their eyes, doesn't really tell you what that person actually looks like.

You can't tell a person's personality when you just look (strictly) into their two eyes. Once you zoom out from those two eyes, your brain starts looking at everything around those eyes. Your brain—your preconceived notions, your past experiences, your emotionally driven thoughts—begins to shape what you “see.”

Some examples,

"He looks evil. Look at that glare!"

That's simple positioning. The chin/head is tilted downward and the eyes are peering upward, making the person look a bit mean. The more the head is tilted downward and the eyes gaze upward, the edgier the image becomes.

"Look at his eyebrows. He looks evil and mean. He looks angry." Therefore, they must be mean.

That is your perception. Not necessarily true.

"Did you see how he looked at me. It gave me the creeps."

I don't discount the feeling you get from an individual. Some people have naturally strong eyes. The darker the iris, the "darker" it usually looks. This is still a subjective opinion placed on a person based on your emotions and past experiences.

Interestingly, the same people who post questions like this also post the question "How do I know when I'm talking to a psychopath?" Or "I'm considering dating this girl, how do I know if she's a narcissist?"

In fact, psychopaths, sociopaths, and narcissists can be charismatic despite their Ability to harm others. Basing your opinion on someone's eyes (and facial expressions) is tantamount to prejudice.

Behavior is key. Look at people.

Perception can lead us to self-deception.