Final answer:
In the brain, people follow the crowd primarily due to social influence, which manifests as normative and informational influence leading to conformity and groupthink. These influences cause individuals to align their thoughts and behaviors with those of the group, particularly when the group is perceived as more knowledgeable or the situation is ambiguous.
Step-by-step explanation:
What happens in the brain that causes people to follow the crowd? This question taps into the psychological concept of conformity, where social influence affects individuals' behaviors and decisions. Solomon Asch's studies suggest two main reasons for conformity: the desire to be accepted by the group (normative influence) and the belief that the group is more knowledgeable (informational social influence). When groupthink occurs, individuals may align their opinions with what they perceive to be the group consensus. This can often lead to suppressed diversity in opinions and can potentially result in faulty decisions. The phenomena of conformity, groupthink, and obedience to authority, as demonstrated in Stanley Milgram's experiments, highlight the impact that group dynamics and perceived authority have on our actions.
Considering the options and the reference material, the correct answer is likely C) Signals that control thinking make people rely on others for information, as people may conform when they believe the group is better informed, or the situation is ambiguous and they need guidance. Emergent-norm theory similarly states that crowds can develop their own definitions of the situation, indicating a reliance on group norms and knowledge over individual judgment.