Voters watching tonight’s highly anticipated debate between Kamala Harris and Donald Trump should watch for signs of emotional confusion on both faces, a leading expert on microexpressions tells the Daily Beast.

Microexpressions are “the universal facial expressions of our species,” expert Annie Särnblad explained, meaning they are universal across humans, despite cultural and regional differences. This is also what makes them difficult to hide, she said, adding that “they precede the thought process.”

“They are involuntary and last only a fraction of a second.”

Särnblad, who previously analyzed Harris’ CNN interview, has a master’s degree in cultural anthropology and is also certified in the Facial Action Coding System (FACS). Tonight, Särnblad will exclusively analyze for the Daily Beast what microexpressions she sees on the candidates’ faces.

A televised debate is a “high-stakes situation,” says Särnblad. “So we’re going to look at whether the facial expressions match the words, because the micro-expressions precede the thinking process.”

“Remember, (microexpressions) tell you what they’re feeling. Not what they’re thinking,” Särnblad said. “For example, if I say, ‘I hate broccoli,’ and I show the microexpression of disgust, that makes sense because I’m talking about something very negative.”

However, a noticeable discrepancy can often arise when someone tries to hide what he or she is feeling by using positive words, but shows negative microexpressions.

She added: “When I’ve worked with my clients myself to prepare them for high-stakes public debates or negotiations, I try to get them to focus on answering the questions they’re going to be asked. We all know that trick of deflecting and answering the question you wanted to be asked instead of answering honestly. But I think the public is smart enough to see through that.”

Särnblad said she will also continue to look at what candidates do to calm themselves down under pressure.

“One of the universal things about body language is that we humans touch our skin when we get nervous,” Särnblad said. “One of the really interesting things about politicians is that they use the self-calming technique of doing the steeple, which is basically a way of calming yourself down by touching your skin.”

She added: “It seems like a powerful position, but it’s actually used to calm your nervous system.”

In the run-up to the debate, the Harris camp reportedly requested that the microphones be left on while the opposing candidate answered a question.

The 6-foot-3 Trump, for his part, has requested that no boxes or elevators be allowed at the event. It would result in him towering over Harris (reportedly 5-foot-10) if they were allowed to walk across the stage, as Trump famously did during his debate against Hillary Clinton in 2016.

Annie Särnblad is the author of three books: “Diary of a Human Lie Detector: Facial Expressions in Love, Lust, and Lies”; “The Facial Expressions Glossary: ​​​​Business Version”; and the recently published “Annie and the Secret Language of Faces”.

The above videos were produced by Emma Särnblad.