功能磁共振成像对解剖的道德判断

Personal moral dilemmas involve directly harming one person to achieve a goal, like harvesting organs to save others. Impersonal moral dilemmas involve indirectly harming someone, such as stealing a boat to rescue people during a hurricane. Personal dilemmas typically trigger stronger emotional responses, while impersonal ones rely more on reasoning processes.

In the trolley dilemma, most people pull a switch to divert a train, killing one to save five. In the footbridge dilemma, most refuse to push a man off a bridge to achieve the same outcome. Although reason would dictate both save five lives, pushing the man triggers stronger negative emotions, causing emotion to override logical reasoning in ways that thinking too much impairs decision making.

The medial frontal gyrus, posterior cingulate gyrus, and angular gyrus—areas linked with emotion processing—show significantly greater activity during personal moral dilemmas. In contrast, the middle frontal gyrus and parietal lobe, associated with reasoning, are more active during impersonal dilemmas requiring logical analysis.

Participants view 30 scenarios across three screens per dilemma. The first two screens display text describing the scenario, while the third screen poses a question asking whether the action is appropriate or inappropriate. Participants respond using a button box, allowing researchers to segment neural responses relative to decision-making processes.

Images are co-registered across all participants using a 12-parameter automatic algorithm to align them to a standard template. They are then smoothed with an 8-millimeter Gaussian filter to reduce noise and improve statistical power for detecting brain activity differences across conditions.

Psychopaths often retain intact reasoning but commit immoral acts, suggesting they lack emotional responses signaling wrongdoing. Research on emotion and reason in moral judgment indicates psychopaths may benefit from therapy fostering specific emotions toward immoral actions, addressing the emotional deficit underlying their behavior.

Political divides often stem from personal moral differences driven by emotional responses rather than pure reasoning. Because emotions strongly influence moral judgments, individuals become less responsive to reasonable arguments from opposing parties. This demonstrates that emotions are fundamental forces shaping how people evaluate moral and political issues.