A Crowd is a large group of persons who are usually strangers, that can facilitate or inhibit certain behaviors.
Social facilitation is the increase in performance of an individual in the presence of a crowd.
Social inhibition is the decrease in performance of an individual in the presence of a crowd.
Deindividuation in crowds refers to the increased tendency for subjects to behave irrationally or perform antisocial behaviors when there is less chance of being personally identified,
The bystander effect: an individual may feel inhibited from taking some action because of the presence of others.
The Informational influence theory states that we use the reactions of others to judge the seriousness of the situation.
The Diffusion of responsibility theory says that, in the presence of others, individuals feel less personal responsibility & are less likely to take action in a situation where help is required.
Group polarization is the phenomenon in which group discussion reinforces the majority’s point of view & shifts that view to a more extreme position. a.k.a. the risky shift phenomenon.
Groupthink refers to a group making bad decisions because the group is more concerned about reaching agreement & sticking together, than gathering the relevant information & considering all the alternatives
Robert C. Gates