This document provides a detection-response task mainly intended for assessing the attentional effects of cognitive load on attention for secondary tasks involving interaction with visual-manual, voice-based or haptic interfaces. Although this document focuses on the assessment of attentional effects of cognitive load (see Annex A), other effects of secondary task load may be captured by specific versions of the DRT, as further outlined in Annex B. Secondary tasks are those that may be performed while driving but are not concerned with the momentary real-time control of the vehicle (such as operating the media player, conversing on the phone, reading road-side commercial signs and entering a destination on the navigation system).NOTE According to this definition, secondary tasks can still be driving-related (such as in the case of destination entry).This document does not apply to the measurement of primary (driving) task demands related to the momentary real-time control of the vehicle, such as maintaining lane position and headway or responding to forward collision warnings. However, this does not preclude that the DRT method, as specified in this document, may be adapted to measure such effects.This document applies to both original equipment manufacturer (OEM) and after-market in-vehicle systems and to permanently installed, as well as portable, systems.It is emphasized that, while the DRT methodology defined in this document is intended to measure the attentional effects of cognitive load, it does not imply a direct relationship between such effects and crash risk. For example, taking the eyes off the road for several seconds in order to watch a pedestrian may not be very cognitively loading but could still be expected to strongly increase crash risk.