You've sat through a speech or TED Talk that leaves you inspired and energized. And you've surely also experienced presentations that are downright coma-inducing. Obviously, when you're the one on stage you want to be in the former camp. 

The question is, how? Behavioral researcher Vanessa Van Edwards has studied hundreds of TED talks in search of answers. While factors such as intelligence, credibility, and charisma are important, her research returned a few surprises too--namely, what you don't say may be just as important as the contents of your speech.

"We had different trials. Some participants got to watch the participants with sound and others without, and we asked them to rate charisma, intelligence, and credibility, and it was incredible that the ratings were the same," says Van Edwards. "There was sort of this unspoken quality."

So how do you say it without saying it? Here are four behavioral patterns pulled from the most popular TED Talks

1. Bring Out the Jazz Hands.

A speaker's body language is extremely important for determining a talk's success. By analyzing specific patterns, the study, which was conducted by Van Edwards's company Science of People, found that the more hand gestures a speaker used, the more successful the talk. Van Edwards says prior research has shown that we have an easier time trusting people when we can see their hands. In addition, when speakers use their hands to explain concepts, people have an easier time understanding them.

2. Don't Be Tone Deaf.

Study participants also rated TED speakers on vocal variety: for instance, fluctuation in voice tone, volume, and pitch. The more vocal variety speakers had, the more views their talks received online. Vocal variety increased both the speaker's charisma and credibility rating. Jamie Oliver, who even yelled at the audience during his talk, was one of the highest rated speakers, and his speech has nearly 6 million views. 

Think about what this could mean for your elevator pitch.

"It's more important to speak your pitch in a new way, not with the perfect words--it can get boring if you are memorizing. It's more important to add vocal variety. People are more interested in the tonality and emotionality," says Van Edwards.

3. Smile, You're Looking Smarter.

According to Van Edwards's report, this finding is the only pattern that goes against current research, as other studies have found that leaders typically smile less. Nonetheless, her study reveals that the longer a TED speaker smiled, the higher his or her perceived intelligence ratings were. Even when speaking about serious topics--like Sheryl Sandberg's talk on the scarcity of women in leadership positions--those who smiled for at least 14 seconds were perceived as having a higher intelligence than those who smiled for less time.

4. You Have Seven Seconds.

When you do smile, make sure you do it in the first seven seconds of your talk, says Van Edwards. The ratings revealed that people had already made their first impression of, and decision on, the talk within the first seven seconds of the video. According to the report, "researcher Nalini Ambady calls this 'thin-slicing.' She says that for efficiency purposes, the brain makes very quick judgments of people within the first few seconds of meeting them."

Check out the following Ted Talks to see these nonverbal cues in action: