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. (3) STOP OR DECREASE SPEED. Hand and arm extended downward. (Acts 1980, No. 80-434, p. 604, §6-106.)