In the UX world they are usually called urgency or scarcity triggers [1][2]. They also play in to the social default bias [3] people tend to have, where when al

In the UX world they are usually called urgency or scarcity triggers [1][2]. They also play in to the social default bias [3] people tend to have, where when alone you tend to do things that you know others have done. 1: https://www.researchgate.net/publication/259906084_Scarcity_messages_A_consumer_competition_perspective https://www.researchgate.net/publication/259906084_Scarcity_... 2 (PDF): https://www.uvic.ca/socialsciences/economics/assets/docs/seminars/Online%20Scarcity%20Informational%20Value1015.pdf https://www.uvic.ca/socialsciences/economics/assets/docs/sem... 3: https://www.coglode.com/gem/social-default-bias https://www.coglode.com/gem/social-default-bias