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. Humans are wired for collaboration when in groups and the protection of the group becomes a priority once in it. Group members try to minimize conflict and reach a consensus decision without critical evaluation of alternative viewpoints by actively suppressing dissenting viewpoints, and by isolating themselves from outside influences.
One useful counter-measure to ask yourself: How much of my decision-making is based on not wishing to cause conflict? Am I sure that the main opinion of the group is valid?
For a full list of the most common biases, click here.