A new category of "Aha!" driven by touch: A grip sensation into the directional seam on a baseball.

We report an "Aha!" experience which differs from conventional Aha's studied over a century in psychological science. The Aha we introduce is driven by touch instead of the visual and verbal modalities widely studied to date. It can occur when gripping a baseball, with a simple input that the red seam on the ball has a direction. Aided by a symmetry analysis and subsequent survey over literature, we show how our mental and physical representation of a baseball can change suddenly by the seam direction and unravel the factors that make the tactile sense into a joyful-and-insightful sensation. Our study sets a new category of Aha driven by touch, opens a new path to investigate the role of touch in our cognition process, reveals the seam direction as a new degree of freedom in baseball aerodynamics and pitching mechanics, and deepens the insights into throwing a baseball from our fingertips.