詳しいガイド（英語）
Meaning and tradition
Vitarka is Sanskrit for reasoning or discussion. The gesture belongs to Buddhist iconography: statues and paintings show the Buddha with the right hand raised and the thumb and index finger joined, representing the act of teaching and debate. It is a gesture seen in depictions of the Buddha, not a health mudra from the classical hatha yoga texts. It appears in several variations in Buddhist art, and the version described here is the common one.
The thumb and index circle is also found in Gyan and Chin Mudra, which is why the element association (fire and air) is borrowed from the finger map used in modern hasta mudra systems.
How to practice
Sit in Easy Pose or Lotus Pose. Rest the left hand in the lap. Raise the right hand to chest height, palm forward, and join the thumb and index fingertips into a circle with the other three fingers extended upward.
Breathe slowly through the nose. Dirga Breath gives a steady rhythm. Hold for a few breaths up to five minutes, then lower the hand and repeat on the other side if you like.
Tips and common mistakes
Keep the elbow close to the body and the shoulder down. Lifting the hand tends to hike the shoulder up.
Know the neighbors. Unlike Abhaya Mudra, where the raised palm is open with all fingers together, here the thumb and index fingertips touch. Unlike Gyan Mudra and Chin Mudra, where the hands rest on the knees, here the right hand is raised to chest height with the palm forward. Unlike Dharmachakra Mudra, which uses both hands at the chest with two circles touching, Vitarka uses one raised hand and the left hand rests in the lap.
Keep the circle soft and the other fingers relaxed rather than stiff.
Tradition vs. evidence
The meaning of this gesture is religious and symbolic. No research shows that it improves reasoning or communication. What is defensible is that a clear, effortless hand position gives attention something to settle on and pairs well with slow breathing.