Basically, the tendency of a group to make decisions that are riskier than most of the individuals would make on their own. When people interact with each other to make a decision, there is a certain level of trust in other members of the group. Because there are others to share the risk and consequences of a decision, members of the group tend to feel more secure and are willing to accept more risk than they normally would on their own. Also, because of the effects of groupthink, some individuals who might not be so willing to accept the risk are motivated to agree with the majority of the group.