Back to Articles

Truth vs. Lies: Which Requires More Self-Control?

Harvard study reveals whether lying or truth-telling demands more self-control. Discover what your answer says about your trustworthiness.

KELLY MCGONIGAL
Jul 21, 2025
2 min read(262 words)
Truth vs. Lies: Which Requires More Self-Control?

The Psychology of Honesty and Deception

A groundbreaking Harvard study reveals surprising insights about truth-telling versus lying. Researchers discovered that:

  • For honest people: Truth-telling is automatic (no extra brain effort)
  • For flexible moralists: Honesty requires conscious self-control
  • Key brain areas: Anterior cingulate cortex and dorsolateral prefrontal cortex activate when resisting temptation

How the Study Worked

Participants played a game where they could:

  1. Guess answers to questions
  2. See the correct answer before reporting
  3. Earn money for correct guesses (with opportunity to lie)

Researchers tracked brain activity during decision-making.

Key Findings About Self-Control

  • Natural truth-tellers: Showed no increased brain activation when being honest
  • Occasional liars: Required significant self-control to tell the truth
  • Moral flexibility: Participants who considered lying as an option struggled with honesty

What This Reveals About Trustworthiness

Two Approaches to Morality:

  1. Principled honesty: Automatic truth-telling without temptation
  2. Situational honesty: Requires active resistance to cheating urges

Practical Applications for Better Decision-Making

Strategies to Strengthen Self-Control:

  • Adopt absolute principles: Like religious/philosophical truth commandments
  • Reduce decision points: Avoid weighing pros/cons for each temptation
  • Reframe choices: See each decision as part of a lifelong pattern

Beyond Honesty: Universal Self-Control Lessons

This principle applies to:

  • Breaking bad habits (smoking, overspending)
  • Building good habits (exercise, productivity)
  • Maintaining relationships

Conclusion: The Power of Committed Choices

By taking firm stances rather than deliberating each temptation, we:

  • Reduce cognitive load
  • Increase consistency
  • Build stronger character

Your approach to truth-telling reveals much about your moral framework and self-control capacity.

KELLY MCGONIGAL