Assessing the Visual-Spatial Workload Demands of Simulated Automobile Driving

1. Garett Howardson, Ashley Arens, Amanda Kjelden & Jessica Johnson (Faculty Sponsor: Frank Schieber) Abstract Method Results Rapid advances in the complexity of automobile instrument panel interfaces (e.g., route guidance systems, internet-in-the-car) compete for the driver’s cognitive resources often at the expense of driving safety. Techniques are needed to better understand the mental workload demands of multitasking while driving. A novel subsidiary-task (the “clock task”) was developed to assess driver mental workload requirements while negotiating different segments of a curve. Consistent with expectations, results revealed that reaction time performance on the subsidiary-task increased while driving in curves and decreased in straight road segments. Although statistically significant, the effects observed may be too small for practical on-the-road assessment applications. Mean reaction times for each segment were as follows: M1 = 1.29, M2 = 1.47, M3 = 1.44, M4 =1.50, M5 = 1.41 Clock Task Latency ANOVA: (N=17) F (4, 64) = 5.08, p<.004 (Greenhouse-Geisser corrected) Pairwise comparisons: Segment 1 < Segments 2, 3, 4, 5 Segment 5 < Segment 4 Participants: Twenty unpaid volunteers were recruited from an undergraduate psychology class with normal hearing and visual acuity. Apparatus and Materials: A driving simulator was set up using a computer equipped with Daimler-Chrysler simulation software, monitor, USB steering wheel, and USB gas and brake pedals. SoundGen software administered the clock-task and responses were recorded using a head set microphone. Goldwave software was used to digitize the voice recordings. Procedure: After completing the informed consent, subjects’ hearing and eyesight were tested. They were informed that the hands of a clock always form two angles. Their task was to listen to a time-of-day stimulus, imagine that time, and answer “yes” if the hands of the clock formed one angle less than 90 or “no” if neither angle was 90 degrees or less. After the participants practiced answering several clock-task cues, they practiced using the Daimler Driving Simulator. Positioned at the start of the second curve, participants were instructed to accelerate to full speed by the first sign post where the clock task begins. The subjects did this for curves two through seven. Next, they were instructed to drive through curves five through seven without listening to the clock-task stimuli. Lastly, they were told to drive through curves four through nine while once again answering the clock-task questions. The actions on the driving simulator, the clock-task cues given by SoundGen, and the participants’ responses were recorded on a blank video tape Assessing the Visual-Spatial Workload Demandsof Simulated Automobile Driving Introduction The Multiple Resource Theory states that the presence of multiple pools of attention are each specific to different types of resources (Wickens, 1984). One example of the different types of resources is the visual-spatial domain. The visual-spatial domain is the primary domain of mental resources used during driving. Currently, lawmakers are debating whether legislation should ban people from engaging in secondary tasks while driving, such as using hand-held cell phones or GPS navigation systems. Studies are being conducted to determine just how dangerous these tasks are. A recent study by Schlorholtz (2006) investigated possible relationships between secondary visual-spatial tasks and elevated mental workload. Historically, driving simulators have been used in place of real vehicles when there was a concern for the safety and well-being of the participants involved with the study. Because our study pushed the mental capabilities of our participants, we used a driving simulator. Discussion Although a statistically significant difference was found between segment 1 and all other segments, the fact that segment 5 is statistically slower than 1 may be due to a lack of concentration from the participant. Subjects may think that once they have exited the curve, their responses to the clock task are not as important as during the curve and devote less processing capabilities to the task. Future studies should utilize a subjective mental workload measure, such as the NASA-TLX, to asses the subject’s perceived mental workload. The development of techniques used in our study that quantitatively assess the relative demands of driving may contribute toward efforts to screen drivers suffering from cognitive impairment. However, since the effect we found was so small, we do not believe the clock-task would be an effective measure of mental demands in real world driving situations.