Blinkers are also known as blinders. They are the piece of horse tack that prevent the horse seeing to the rear and, in some cases, to the side. Trainers believe these keep the horses focused on what is in front, encouraging them to pay attention to the race rather than other distractions, such as crowds.
To keep moving forward at times you will need to put your blinkers on to stay in your lane.
Sources: Wikipedia / Photo credit: click here.