1) Deciding 2) Decision making 3) Decision making by a group 1) Hive mentality 
Groupthink is a psychological phenomenon that occurs within a group of people, in which the desire for harmony or conformity in the group results in an irrational or dysfunctional decision-making outcome. Group members try to minimize conflict and reach a consensus decision without critical evaluation of alternative viewpoints, by actively suppres...
the tendency of group members to conform by adopting a narrow view of some issue
A deterioration of mental efficiency, reality testing, and moral judgment in a group that results from an excessive desire to reach consensus.
Groupthink is when people discourage a person from thinking a certain way or making decisions using individual creativity.
noun decision making by a group (especially in a manner that discourages creativity or individual responsibility)
The tendency of a decision-making group to filter out undesirable input so that a consensus may be reached, especially if it is in line with the leader's viewpoint.
The tendency of a close-knit group to emphasize consensus at the expense of critical thinking and rational decision making. 
A term coined by Irving Janis that refers to the tendency of people in positions of power to follow the opinions of the group, to the point that there is a narrow view of the issue at hand.
decision making by a group