To shed some light on why this is happening in the first place, it may be helpful to understand the innervation of the muscles on these fingers.
There are two nerves that innervate the little finger, both branches of the superficial ulnar nerve. One of them is exclusive to the little finger, but the other (the common palmar digital nerve) actually branches again and innervates both sides of the gap between your little finger and ring finger. This explains why contracting your little finger muscles causes some (but not complete) contraction of your ring finger.
These connections can be modified and trained with practice, like many other movements we can improve with practice.
Iannotti, Joseph P, and Parker, Richard. Netter Green Book Collection : The Netter Collection of Medical Illustrations: Musculoskeletal System, Volume 6, Part I - Upper Limb, Volume Vol. 6 : Musculoskeletal System, Volume 6, Part I - Upper Limb (2). Saint Louis, US: Saunders, 2012. ProQuest ebrary. Web. 29 November 2016.