All signals given by hand and arm shall be given from the left side of the vehicle in the following manner except as indicated for pedalcycles and motorcycles and the signals shall indicate as follows:
(1) For a left turn, the hand and arm shall be extended horizontally.
(2) For a right turn, the left hand and arm shall be extended upward, except that operators of motorcycles and pedalcycles may also be permitted to signal a right turn by extending the right hand and arm horizontally.
(3) To stop or decrease speed, the left hand and arm shall be extended downward.