Finger paddles, sometimes also known as sculling paddles, are frequently touted as paddles that help swimmers increase their "feel for water." Evidence to support this claim, however, is never provided.
One way to think about the feel for water in this particular context is as a sense of the position and the movement of the swimmer's hand in the water. This sense is vital when swimmers want to improve technique. For instance, if a swimmer tries to improve her hand entry and catch, she needs to be aware of the precise position and movement of her hand first. Once she has that awareness, she can work on improving it. In other words, she cannot improve something that she is not aware of. Mindful swimmers work hard to increase their feel for water so they can then refine their technique.
Where does this sense of the position and movement, or the feel for water come from? What events trigger this awareness? What information does the brain receive that allows it to create an accurate map of the swimmer's hand position?
This information starts with the fingertips. Fingertips are one of the most sensitive regions of human body. In fact, "there is a hundred-to-one ratio of touch receptors in your fingers compared to your torso." The more sensory receptors, the more information reaches the brain. It is this information, originating from the fingertips and processed by the brain, that allows the swimmer to know her precise hand position and the movement in the water.
They key point to understand here is that when the swimmer presses the water, the fingertip receptors are activated. "These special receptors translate mechanical pressure into long-distance electrical signals" and send them to the brain. The brain then processes this information and provides the swimmer with a sense of the hand position and movement, or the feel for water. It is important to emphasize that the source information provided by the fingertip touch receptors determine the feel for water.
Now that we have this insight, it is easy to see that the feel for water with the finger paddle will be quite different from the feel for water with bare fingers. When you press water with bare fingers, the water flows around, over and between the fingers. The finger receptors, having direct and unobstructed contact with water, collect accurate and relevant information and send it to the brain, resulting in the accurate feel for water. Inserting a finger paddle between the fingers and the water dramatically changes the information collected by the fingertip touch receptors: the sensory input from water, a liquid, is fundamentally different from the input from a solid paddle.
By shifting the fingertip touch receptors from water and placing them onto a solid surface, finger paddles deprive the fingertip touch receptors from registering as much crucial information necessary to increase the feel for water. In essence, you create a barrier between the sensory collector and the environment. It's analogous to putting on opaque glasses to see more. Your eyes may register the inside of the glasses, but they won't register what is beyond them.
In conclusion, to increase the feel for water, it is crucial to have unobstructed contact between the fingers and the water. Only when the fingers have unobstructed contact with water, the fingertip receptors can provide the brain with accurate and relevant information that will result in a more accurate feel for water. Inserting a finger paddle between the fingers and the water will only increase the feel for solid surface. In this case, swimming with finger paddles is more likely to increase the feel for plastic than the feel for water.