Can't unify, to get overall impression of complex shapes and spaces. Can't recall complex spatial patterns. Katz noted - palpation is distal. A moving fingertip gives more spatial information than an immobile one feeling twists and turns of a raised line. Passively guided contacts are better than actively moving contacts.
Touch uses joints, tendons and muscles.
Basically - All perception depends on proximal input. This is a set of variations at the receptor, providing information about the world i.e. the distal objects. The medium for transmitting light or allowing observer movement. The receptor which transduces energy. The nerves which transmit impulses.