Question

Difficulty: MediumPhysiological Effects of Alcohol on Driving Performance

While operating a motor vehicle at night, an impaired driver tends to fixate straight ahead on the road and fails to notice a pedestrian stepping onto the crosswalk from the side shoulder. Which physiological effect of alcohol directly accounts for this critical safety hazard?

  1. Narrowing of the driver's peripheral vision, leading to a restricted visual field often described as 'tunnel vision'Answer
  2. B
    Failing to conduct a shoulder check due to incorrect reliance on side mirrors alone
  3. C
    Assuming legal driving ability as long as blood alcohol concentration remains below statutory limits
  4. D
    Misjudging posted safe driving speeds under basic speed law regulations

Answer

Narrowing of the driver's peripheral vision, leading to a restricted visual field often described as 'tunnel vision'
Alcohol acts as a central nervous system depressant that degrades sensory processing. One of its primary physiological impacts on vision is the restriction of peripheral vision (side vision), causing 'tunnel vision.' As a result, impaired drivers lose the ability to detect hazards approaching from the sides without turning their head completely.

Step-by-Step Solution

1
Identify the scenario's key symptom
The driver fixates straight ahead and misses hazards appearing from the side of the vehicle.
Fixating centrally without noticing lateral hazards indicates a deficit in side vision and visual scanning.
2
Map the symptom to physiological alcohol effects
Alcohol consumption reduces peripheral visual acuity and impairs the eye muscles responsible for peripheral scanning.
This sensory narrowing restricts visual field width, making it difficult to detect objects outside the central line of sight.

Key Concept

Effect of alcohol on peripheral vision and visual field width
Estimated Time:1m 0s
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