It's always tough to determine the appropriate amount of time to hold someone's gaze. Too short, and you risk seeming bored or distractible; too long, and you look like you might be a robot, or flirting.
The conventional wisdom is that people who make unflinching eye contact are more trustworthy, but a new study (noticed by Katy Waldman at Slate) suggests that if you’re arguing with someone who disagrees with you, you’ll be more likely to persuade them if you don’t look directly into their eyes. Researchers at the University of British Columbia had twenty participants watch a video of pundits that they disagreed with, and instructed some to focus their gaze on the speaker’s eyes and others to focus on the speaker’s mouth. They discovered that participants who watched the pundits’ eyes found their arguments less convincing than those who looked at the speaker’s mouth instead.
Researchers speculated that this is probably because making long, extended eye contact is often uncomfortable — and even intimidating and scary. A dissenting listener may already feel defensive and is likely to sense sustained eye contact as a threat.
But shifty eyes aren't always less creepy than intense eye contact. The study also found that people who watched pundits they agreed with tended to look at the speaker’s eyes, which, in such circumstances, can facilitate deep connection and bonding. So, as always: Know your audience.