Scanning, blind spots and signaling

Key points

1. 90% of driving decisions are based on what you see.

   Source: Handbook p. 49

   “Driving requires decision making and critical thinking, and 90% of driving decisions are based on what we see.”
   Montana Driver Manual, Handbook p. 49

2. Sending or reading a text takes your eyes off the road for 5 seconds; at 55 mph that is a football field driven blind.

   Source: Handbook p. 49

   “Sending or reading a text takes your eyes off the road for 5 seconds. At 55 mph, that’s like driving the length of an entire football field while blindfolded.”
   Montana Driver Manual, Handbook p. 49

3. In the city, 10 seconds is about one block, so look at least one block ahead. On the highway, 10 seconds is about a quarter of a mile.

   Source: Handbook p. 52

   “In the city, 10 seconds is about one block. When you drive in city traffic, try to look at least one block ahead. On the highway, 10 seconds is about four city blocks or a quarter of a mile.”
   Montana Driver Manual, Handbook p. 52

4. Watch for red light runners, especially just after your light turns green.

   Source: Handbook p. 53

   “Always be watchful for red-light runners. This is especially important just after your light has turned green.”
   Montana Driver Manual, Handbook p. 53

5. Look over your shoulder in the direction you plan to move. The blind spots near your rear corners cannot be seen in your mirrors.

   Source: Handbook p. 54

   “Look over your shoulder in the direction you plan to move. Be sure no one is near the rear corners of your vehicle. These areas are called “blind spots” because you cannot see them through your mirrors.”
   Montana Driver Manual, Handbook p. 54

6. When backing, turn and look directly through the rear window instead of relying on mirrors.

   Source: Handbook p. 55

   “Place your right arm on the back of the seat and turn around so that you can look directly through the rear window. Do not depend on your rearview or side mirrors as you cannot see directly behind your vehicle.”
   Montana Driver Manual, Handbook p. 55

7. Tinted and some photo gray lenses can cut up to 30% of your night vision.

   Source: Handbook p. 55

   “Even tinted and some “photo gray” lenses can detract up to 30% of your night vision.”
   Montana Driver Manual, Handbook p. 55

8. When you are tired, stop at least every two hours for a short break.

   Source: Handbook p. 55

   “When you are fatigued, stop at least every two hours for a short break”
   Montana Driver Manual, Handbook p. 55

9. If you will stop or slow down where other drivers do not expect it, tap the brake pedal three or four times quickly.

   Source: Handbook p. 58

   “If you are going to stop or slow down at a place where another driver does not expect it, tap your brake pedal three or four times quickly to let those behind you know you are about to slow down.”
   Montana Driver Manual, Handbook p. 58

10. Montana requires at least 20/40 vision in at least one eye, with or without corrective lenses.

    Source: Handbook p. 70

    “This test measures that you have at least 20/40 vision in at least one eye, with or without corrective lenses.”
    Montana Driver Manual, Handbook p. 70

Numbers to know

3 questions from the Montana practice test

1. 1. What share of driving decisions are based on what we see, according to the Montana manual?

   1. 50 percent
   2. 25 percent
   3. 10 percent
   4. 90 percent
   Show answer

   90 percent. Driving requires decision making and critical thinking, and 90 percent of driving decisions are based on what we see. That is why Montana requires a vision test before issuing a license, measuring at least 20/40 vision in at least one eye, with or without corrective lenses. The manual also recommends having your eyes checked regularly. Keep windows and lights clean so you can see and be seen, because 50, 25 and 10 percent understate the figure.

2. 2. Which check is required immediately before changing lanes?

   1. Look over your shoulder for traffic in the blind spot
   2. Rely on the rearview mirror without turning your head
   3. Check only the lane ahead and ignore traffic behind
   4. Turn on hazard flashers and move without signaling
   Show answer

   Look over your shoulder for traffic in the blind spot. Mirrors cannot show every area beside and behind a vehicle. Montana tells drivers to look over the shoulder in the direction of movement because the rear corners are blind spots. Mirror-only scanning can miss a motorcycle or car positioned outside the reflected view. Ignoring traffic behind removes a crucial safety check, and hazard flashers do not communicate which lane you intend to enter. Signal, inspect the mirrors, then make a quick shoulder check immediately before moving so the decision reflects current traffic.

3. 3. About how long does sending or reading a text take a driver's eyes off the road, and what does that equal at 55 mph?

   1. About 5 seconds, like driving the length of a football field blindfolded
   2. About 1 second, like driving one car length
   3. About 10 seconds, like driving one mile
   4. About 2 seconds, like crossing one intersection
   Show answer

   About 5 seconds, like driving the length of a football field blindfolded. Texting combines manual, visual, and cognitive distraction, which is why the manual calls it the most alarming distraction. Sending or reading a text takes your eyes off the road for 5 seconds, and at 55 mph that is like driving the length of an entire football field blindfolded. One or two seconds understates the time, and 10 seconds and a mile overstate it. Pull over and stop before handling a phone.

Source: the Montana Driver Manual, Chapter 5: How to Drive Safely. This lesson is a plain English summary, not the law itself; where it differs, the manual and the statute govern. Last checked 2026-09-27.