The impact of secondary task cognitive processing demand on driving performance Myra Blanco, Wayne J. Biever, John P. Gallagher, Thomas A. Dingus

Introduction Recently, concerns have been raised about the distraction potential of Intelligent Transportation Systems (ITS) technologies. Research on the visual demand of secondary tasks has been ongoing for many years. But much less is known about the impact of newer in- vehicle tasks and their potential for substantial cognitive demand.

Lee et al.(1997) characterized the information flow with 13 different decision-making elements. Only 4 of the 13 elements were selected (Search, Compute, Plan, and Interpret) for this research because of their occurrence in route selection tasks.

Objective The objective of this research is to make progress in determining which IVIS task characteristics will allow drivers to perform the required cognitive and visual time-sharing tasks effectively.

Experiment 1 :the effects of cognitive demand levels on driving performance when IVIS tasks are presented in a visual display to light- vehicle drivers. Experiment 2: Similar to Experiment 1, the participants were heavy-truck drivers. Experiment 3: The IVIS tasks as auditory displays to light-vehicle drivers.

Method 受測者 : Thirty-six drivers participated in Experiments 1 and 3, and experiment 2 was performed with 12 male truck drivers. 採用實車實驗，並有前車。

Experimental design The visual-display experiments used a Mixed Factorial Design with four independent variables. (IVIS type of task, presentation format, information density, and age) 實驗三並不包括 presentation format

Age The three age groups for Experiment 1 and 3 were young (18 – 25 years), middle-aged (35 – 45 years), and older participants (65 years and older) For Experiment 2, the two age groups were middle-aged (35 – 45 years) and older participants (55 years and older).

IVIS type of task (1) Search, (2) Search- Compute, (3) Search-Plan, (4) Search-Plan-Compute, (5)Search-Plan-Interpret, and (6) Search-Plan-Interpret-Compute. Four different route-selection task types were presented tothe participants in Experiment 3: (1) Listen, (2) Listen-Plan,(3) Listen-Compute, and (4) Listen-Plan-Compute.

Conventional tasks For Experiment 2, five in-vehicle conventional tasks were included as secondary tasks in additionto the IVIS tasks: (1) activate turn signal, (2) adjust vent, (3) adjust power mirror, (4) monitor fuel level, and (5) monitor vehicle speed

Presentation format (1) table, (2) paragraph, (3) graphic with text.

Information density Low: two categories for each of the three alternatives. Medium: three categories for each of the three alternatives. High: four categories for each of the five alternatives.

Dependent variables Driving performance eye glances to IVIS display subjective scales of the mental workload and situational awareness of the driver.

Procedure 30 min of training The study was performed on a 4-lane divided section of U.S. Route 460 between Blacksburg and Bluefield, Virginia. Experimental runs occurred during daylight The in-vehicle experimenter was able to skip or stop a task under two circumstances.

The participant performed the primary driving task for approximately 2 h. The IVIS tasks, baselines, and conventional tasks were presented in a counterbalanced order.

Experiment 1 results: light-vehicle drivers

Experiment 2 results: heavy-truck drivers

Experiment 3 results: auditory tasks

Discuss For complex in-vehicle tasks, the presence of decisionmaking elements has an adverse substantial impact on driving performance. The decision-making elements must also be considered in conjunction with information density and display format to adequately assess the potential for distraction-related performance degradation.

For visual information displayed for the purposes of decision making, the number of display glances increase greatly even if the driver may not be required to look at the display to complete all of the elements of the task. Complex auditory tasks result in critical degradations in driving performance.( 雖然主觀負荷不高 )