1. conforming one's behaviour or beliefs to that of the majority
Professional
Social
a display of herd mentality
To have a 'herd mentality' means to be influenced in decision making by the people around you and your peers as opposed to making rational decisions. A 'herd' is a collective noun for a group of animals such as cows or sheep and this idiomatic phrase means to behave like an animal - following the others instead of making independent choices and decisions.