Most states only require the use of a blinker if your lane changing or turn is gonna effect someone else's lane of travel. In other words, if you switch lanes and it causes someone to hit their brakes or swerve, you should've used a blinker. If you're at a 4 way stop with a vehicle on the opposite side and both of you wanna make a left turn, blinkers should be used. T-intersections where your facing no other roadway and you're in a turn lane, it's not required. If you're the only car on the road, no blinkers are required.