What makes the synthesis of the two tactile perceptions in one single object impossible, is not so much that the position of the fingers is unaccustomed or statistically rare, it is that the right face of the middle finger and the left face of the index cannot combine in a joint exploration of the object, that the crossing of the fingers, being a movement which has to be imposed on them, lies outside the motor possibilities of the fingers themselves and cannot be aimed at in a project towards movement.