Visual-Manual Driver Distraction Guidelines Test Procedures – Task Acceptance Testing Occlusion and Eye Glance Measurement Using Driving Simulator Testing

NHTSA · 2019 · ROSA P / United States. Department of Transportation. National Highway Traffic Safety Administration

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Summary

This document outlines the standardized test procedures for "Occlusion Testing," a method developed by the National Highway Traffic Safety Administration (NHTSA) to assess visual-manual driver distraction. The procedure is designed to determine whether specific in-vehicle electronic tasks comply with NHTSA’s Guidelines for Reducing Visual-Manual Driver Distraction. The primary motivation is to establish a rigorous, repeatable protocol for evaluating the safety of secondary tasks performed while driving, ensuring that interactions with integrated electronic devices do not excessively divert driver attention from the roadway. The methodology utilizes electronic shuttered glasses that alternate between transparent (viewing) and opaque (occlusion) intervals to simulate the visual demands of driving. The apparatus switches states in less than 20 milliseconds, with a fixed cycle of 1.5 seconds of viewing followed by 1.5 seconds of occlusion. Testing involves 24 participants recruited to ensure a balanced demographic mix across four age groups (18–24, 25–39, 40–54, and 55+) and gender. Participants must be active drivers with valid licenses, good health, and no prior familiarity with the tested devices. Each participant performs five trials of a defined "testable task" after undergoing standardized training and practice. Trials are conducted in a stationary setting using a vehicle mock-up or simulator. Data collection focuses on the Total Shutter Open Time (TSOT), calculated as the sum of viewing intervals required to complete the task. The acceptance criterion for task conformance is strict: a task is deemed acceptable for use while driving only if the mean TSOT is 12.0 seconds or less for at least 21 of the 24 participants. Trials containing performance errors are excluded from the TSOT calculation for acceptability but are retained to assess if a task is "unreasonably difficult." A task is classified as unreasonably difficult and recommended for lockout if errors occur in more than 50% of all trials. If a participant makes errors in three or more of their five trials, their data is excluded from acceptability determinations, and a replacement participant is recruited. The protocol also specifies that testing sessions should not exceed four hours to prevent fatigue-induced performance degradation. The significance of this document lies in its provision of a concrete, regulatory-aligned framework for evaluating in-vehicle technology safety. By standardizing the occlusion method and defining precise statistical thresholds for acceptance, NHTSA provides manufacturers and researchers with a clear benchmark for designing user interfaces that minimize distraction. This ensures that secondary tasks are evaluated based on objective visual demand metrics rather than subjective assessments, ultimately supporting the development of safer in-vehicle electronic systems.

Key finding

A task is accepted for performance by drivers while driving if the mean Total Shutter Open Time is 12.0 seconds or less for at least 21 of the 24 test participants.

Methodology

simulator

Sample size: 24

Provenance

The full processing record for this entry. Every stage of this paper's journey through the pipeline is logged — what ran, with which tool and model, how many attempts it took, and when it last completed. Discovered via bulk_ingest_rosap on 2026-05-23 (6 acquisition events logged).

Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

Topics

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• visual occlusion
• temporal
• visual
• visual manual
• manual
• distraction detection algorithms

Information type

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• Empirical Findings: behavioral performance data
• Methodological Resource: measurement protocol, tool software