Driving: Vision and Perception - Chapter 7

• Chapter 7 focuses on vision and perception in driving, aiming to reduce driving risks by developing effective visual habits
• Drivers need to manage vision, time, and space to minimize risk

The Importance of Vision

• Effective vision is critical for safe driving
• Vision is the most important sense for driving
• A clear field of vision is necessary to gather, assess, and use information to guide your vehicle
• Adequate visibility includes seeing ahead and to the sides
• Line of sight the imaginary line from your eyes to a focus point
• Field of view is the entire visible area of the road and surroundings at any moment

Types of Vision

• Central, fringe, and peripheral vision each provide different information types
• Central vision gives the most detail and is used for targeting a specific object or area
  • Central vision occupies only 3% of the driver's total field of view, roughly equivalent to a dime held at arm's length (5 degrees)
• Fringe vision is used to judge depth and position and provides information about lane position and nearby objects
• Peripheral vision (side vision) encompasses central and fringe vision, is the broadest vision type
  • Peripheral vision detects presence, color and motion, and provides information about potential threats
  • Affected by alcohol, drugs, fatigue, and speed

Color Blindness

• Color blindness is when drivers have difficulty distinguishing colors
• The most common form of color blindness is the inability to distinguish red and green
  • People with color blindness can use cues other than color, like sign shapes and the sequence of lights

Effective Visual Habits

• Several learnable visual habits help manage vision and perception skills, including:
  • Looking versus seeing, organizing the driving brain, searching the total traffic scene
  • Searching selectively and other effective habits
• When driving, it is important to be constantly active by eyes and brain must be fully engaged
  • Effectively “read” and interpret the complete traffic picture by not only looking, but seeing

Organizing Your Driving Brain

• The PDA system which stands for Perceive, Decide, Act. This is useful for gathering, filtering, and acting on driving information
• Step 1: Perceive, or identify events in the traffic scene
• Step 2: Decide, make decisions based on perceived information
• Step 3: Act, take action based on your decision
• Other systems that drivers can use to gather, filter, and act on driving information:
  • Identify, Predict, Decide, Execute (IPDE)
  • Search, Identify, Predict, Decide, Execute (SIPDE)
  • Search, Evaluate, Execute (SEE)

Searching The Total Traffic Scene

• Searching involves moving eyes constantly from near to far and side to side
• The intended path of travel should be the main focus, but searching the total traffic scene gives more additional clues
• When driving, search for vehicles, animals, objects, warning signs, and traffic signs
• The center of your path of travel is the main point of reference

###Visual Search Patterns for Searching Well Ahead

• As a driver you may need to respond quickly to changing traffic events
• To control risk, it's important to develop efficient and orderly visual search patterns to gather information
• Goal is to identify anything that might require adjusting speed or changing position/direction or communicate with other road users
• The distance you look ahead is your identified visual lead
• The 20-to 30-Second Visual Lead gives you the most time to analyze conditions and adjust
• The 12-to 15-Second Visual Control Zone is when adjust your vehicle speed and/or direction before it becomes too late

Searching to the Sides

• Searching to the sides is needed for potential conflicts and hazards
• This can be difficult with objects along the roadside blocking your view
• Peripheral vision can detect hazards approaching from the side
• Concentrating on one object can impair the ability to detect other dangerous conditions

Looking Behind

• Skills to check traffic behind reduces crash risks, like in sudden changes
• Quickly search mirrors for anyone following too closely or preparing to pass
• Check mirror blind areas, they are zones you cannot see from the driver's seat
• Braking Clearance: it is necessary to know what is following you to judge the necessary amount of space for braking
• Mirror Blind Zones: It is important to turn your head slightly to detect vehicles you may not be able to see in your mirrors

Searching Selectively

• Driving decisions that reduce risk start with searching for the right information which is selective searching
• There are two components of a selective search pattern:
  • Directing your search-know where to look, when, and for what
  • Classifying information-Organize the information in your brain and filter it when necessary

Directing your search should include the following:

• Searching for important factors, gathering information, line-of-sight changes, ground viewing
• Off-road obstacles, traffic conditions, and adjusting to visibility changes
• Searching for Important Factors:
  • Look for road hazards, scan for changes in the road ahead, search all intersections, identify conditions that influence traction or any potentially hidden hazards
  • Observe the behavior of other road users, and quickly direct your attention away from the irrelevant

Visibility

• Your LoS continually changes as you drive
• Stay alert to the potential for a limited LoS well ahead
• Ground viewing can help judge another vehicle's speed and any changes in speed
• Off-road obstacles can reduce LoS and cause hidden dangers
• Traffic conditions can reduce sight, speed reduction can help respond if needed
• Adjusting to Visibility Changes: It is important to note the weather, time of day, and season

Adjusting To Visibility Changes

• Daylight Hours and snow/sand glare sharply decrease your ability to see, wear sunglasses
• Sunglasses are effective at reducing glare, avoid thick frame ones
• Night Driving makes it harder to see the same details as daylight
• Driving at Dusk have poor contrast, look for drivers without headlights or using them
• Inclement Weather like snowstorms and rain, wait for the weather to improve if possible

Lights On Laws

• Headlights increase visibility of your car in day light. Use in low visibility.
• Keep your headlights clean.
• Classifying Information: know and understand your surroundings

Classifying Information

• Direct your search, searching selectively involves accurately classifying the information you gather
• It Helps understand your surroundings by noticing significant events and clues
• Signs, Signals, and Road Markings, Road Features, Motorized Vehicles, and Non-motorized Road Users

Non-motorized Road Users

• Pedestrians, bicyclists, animals, and other non-motorized road users are the least protected and predictable road users, know the clues to understanding their actions
• Drivers with poor visual habits:
  • Do not prepare for stops or turns far enough in advance, don't see traffic jams in advance
  • Become trapped behind large trucks, surprised often, unaware of vehicles passing
  • Unaware of their own speed. Don't respond to changes in the traffic environment
  • Drive with dirty or improperly adjusted mirrors/windows, drive with turn signals flashing