625 ILCS 5/11-806

All signals herein required given by hand and arm shall be given from the left side of the vehicle in the following manner and such signals shall indicate as follows: 1. Left turn - Hand and arm extended horizontally. 2. Right turn - Hand and arm extended upward, except that a person operating a bicycle may extend the right hand and arm horizontally and to the right side of the bicycle. 3. Stop or decrease of speed - Hand and arm extended downward.