Although we may think we come to our opinions independently, research shows that people are profoundly influenced by group norms at all levels of thought and behavior. People feel tremendous pressure to conform to group norms and feel anxiety when they go against the group. An fMRI study by Gregory Burns showed increased activation in the amygdala when people made non-conforming decisions. The amygdala is a brain region associated with the fear response. Moreover, a large body of social psychology research illustrates how the pressure to conform can influence even our perceptions of physical reality. The presence of four peers stating a consistently wrong opinion can cause subjects to deny even obvious physical facts, for example, to call a color green when it is clearly blue.