An operator who is permitted to give a hand and arm signal shall give the signal from the left side of the vehicle as follows:
(1) to make a left turn signal, extend hand and arm horizontally;
(2) to make a right turn signal, extend hand and arm upward, except that a bicycle operator may signal from the right side of the vehicle with the hand and arm extended horizontally; and
(3) to stop or decrease speed, extend hand and arm downward.
Official text of the Texas Transportation Code as published by the Texas Legislative Council.