ACTAR Human Factors 5 — Questions and Answers
Question 1: What is 'change blindness' and why is it relevant in traffic accident reconstruction?
- A driver's failure to adjust speed for changing road conditions
- The failure to detect visual changes when there is a brief interruption in the visual scene (Correct answer)
- A legal term for failing to signal a lane change
- Color blindness affecting traffic signal recognition
Correct answer: The failure to detect visual changes when there is a brief interruption in the visual scene
Change blindness—failure to notice changes during a visual interruption—explains why drivers may not perceive sudden changes in a scene even while actively looking.
Question 2: How does sleep deprivation of 17–19 hours compare to alcohol impairment in terms of cognitive performance?
- It is equivalent to a BAC of approximately 0.05%
- It is equivalent to a BAC of approximately 0.10% (Correct answer)
- It produces impairment below the threshold of measurable effect
- It is comparable to a BAC of 0.02%
Correct answer: It is equivalent to a BAC of approximately 0.10%
Research by Williamson & Feyer (2000) found 17–19 hours of wakefulness produces performance impairment equivalent to approximately BAC 0.05%–0.10%.
Question 3: In reconstruction of a pedestrian-vehicle crash, what is meant by the 'available sight distance' for the driver?
- The posted visibility distance on road signs
- The distance from which the driver could first have seen the pedestrian given sight obstructions and lighting (Correct answer)
- The maximum range of the vehicle's headlights
- The legal minimum sight distance required at crosswalks
Correct answer: The distance from which the driver could first have seen the pedestrian given sight obstructions and lighting
Available sight distance is the actual detection range accounting for environmental obstructions, lighting, and the pedestrian's visual characteristics at the specific scene.
Question 4: Which of the following describes the 'expectancy violation' effect in the context of wrong-way driver crashes?
- Drivers expect roads to be two-way and do not anticipate oncoming traffic on a one-way road (Correct answer)
- Drivers have no expectation of meeting other vehicles on highways
- Wrong-way drivers are always impaired and not subject to expectancy
- Expectancy violation only applies to pedestrian scenarios
Correct answer: Drivers expect roads to be two-way and do not anticipate oncoming traffic on a one-way road
Drivers on limited-access highways have a strong expectancy of one-directional traffic; encountering a wrong-way vehicle violates this expectancy, delaying recognition and response.
Question 5: What role does 'selective attention' play in multi-task driving scenarios during accident reconstruction analysis?
- It allows drivers to safely monitor all hazards simultaneously
- It causes some stimuli to go unprocessed when attentional resources are committed elsewhere (Correct answer)
- It is irrelevant unless the driver was texting
- It only applies to novice drivers under 25
Correct answer: It causes some stimuli to go unprocessed when attentional resources are committed elsewhere
Selective attention means the brain prioritizes certain inputs; when resources are committed to one task, competing stimuli may not be processed, potentially causing a missed hazard.
Question 6: What is the significance of 'ecological optics' and the 'looming response' in traffic crash human factors?
- Looming describes a visual expansion of an approaching object that triggers braking responses (Correct answer)
- Ecological optics refers to environmental visibility at crash sites
- The looming response only applies to animal avoidance, not vehicle collisions
- Ecological optics is a photographic analysis technique
Correct answer: Looming describes a visual expansion of an approaching object that triggers braking responses
The looming response is triggered by rapid visual expansion (optical flow) of an approaching object, often initiating emergency braking in drivers before conscious threat assessment occurs.
Question 7: When reconstructing a crash involving driver distraction, which analytical method best quantifies the distraction's effect on pre-crash response?
- Comparing the driver's stated attention level to witness accounts
- Using time-line analysis to compare expected response timing to actual response initiation (Correct answer)
- Estimating distraction severity from the type of in-vehicle device used
- Measuring the driver's heart rate recorded by vehicle sensors
Correct answer: Using time-line analysis to compare expected response timing to actual response initiation
Time-line analysis compares when a response should have occurred (based on normal PRT and detection distance) to when it actually occurred, quantifying the delay attributable to distraction.
ACTAR Human Factors 5
What is 'change blindness' and why is it relevant in traffic accident reconstruction?