Consider the point of words, not whether they are technically lies
Being "caught" on a lie because your emotions are known doesn't take out the effect of words.
You're angry at your wife because she embarrassed you at a party.
"That dress makes you look fat as a hog, but I guess you already knew that because your diet clearly isn't working."
You're lustful for your wife and you're trying to get the foreplay going.
"You look so sexy in that dress, and all the other men at the party were checking you out."
In either of those situations, from the point of view of the other person, would it matter if those statements were technically lies?
Consider that humans already give away their emotions, and tell lies
Humans already display their emotions through a number of tells, such as facial expressions and body language and vocal pitch. Most of the time, and for most people, people are not trained to exert great control over these tells, and so our emotions are not especially challenging to read if one cares enough.
And yet telling lies is still commonplace.
Can a person lie if his eyes tell his emotions?
Yes.
Consider that human behavior has several causes and motivations
For example, I'm angry at someone at work and want them to feel bad about something, so I tell a lie about some of the work they did.
"Your proposal was complete garbage. I know why you failed college."
"Why are you so angry?"
"Because my neighbor's teenage kid was speeding through the street and killed my dog this morning."
It's obvious that the original speaker is angry because of eye color, but it's not obvious which one of those statements are lies.
* Was the proposal actually garbage?
* Or was the presentation of the proposal garbage?
* Or is the underlying idea of the proposal garbage, but all other parts were pretty solid?
* Did the other person actually fail college?
* Did the other person actually go to college?
* Did the other person earn a bachelor's degree, but drop out of his master's program?
* Did the other person fail a class at college, but actually earn a PhD in some topic?
* Did that person's dog actually die that morning, or last week?
* Was it actually the neighbor's teenager, or their adult child?
* Was it actually speeding, or did the dog run in front of them while they were driving the speed limit and looking down to adjust their phone because they just got a text message about their grandma in the hospital?
Any combination of those options could be lies or not lies, and yet it wouldn't change the emotion or effect of the speaker's words. 620