https://phys.org/news/2018-11-subtle-visual-cues-nudge-users.html

The subtle power of these cues could both help people build stronger online communities, as well as possibly lure them into revealing personal information, according to the researchers.

"This shows that little changes can mean a lot and it could help sites, such as online health forums, stay alive and help support their users," said Sundar. "If people don't reveal information in an online forum, the vitality of that forum decreases because not enough people are sharing details that make the forum worthwhile. On the other hand, if spam sites use these cues, they may be able to get more people to reveal sensitive information about their personal life, and that would be a bad thing."