Jakke Mäkelä

The Attentional Demand of Automobile Driving Revisited: Occlusion Distance as a Function of Task- Relevant Event Density in Realistic Driving Scenarios

Objective: We studied the utility of occlusion distance as a function of task-relevant event density in realistic traffic scenarios with self-controlled speed. Background: The visual occlusion technique is an established method for assessing visual demands of driving. However, occlusion time is not a highly informative measure of environmental task-relevant event density in self-paced driving scenarios because it partials out the effects of changes in driving speed. Method: Self-determined occlusion times and distances of 97 drivers with varying backgrounds were analyzed in driving scenarios simulating real Finnish suburban and highway traffic environments with self-determined vehicle speed. Results: Occlusion distances varied systematically with the expected environmental demands of the manipulated driving scenarios whereas the distributions of occlusion times remained more static across the scenarios. Systematic individual differences in the preferred occlusion distances were observed. More experienced drivers achieved better lane-keeping accuracy than inexperienced drivers with similar occlusion distances; however, driving experience was unexpectedly not a major factor for the preferred occlusion distances. Conclusion: Occlusion distance seems to be an informative measure for assessing task-relevant event density in realistic traffic scenarios with self-controlled speed. Occlusion time measures the visual demand of driving as the task-relevant event rate in time intervals, whereas occlusion distance measures the experienced task-relevant event density in distance intervals. Application: The findings can be utilized in context-aware distraction mitigation systems, human–automated vehicle interaction, road speed prediction and design, as well as in the testing of visual in-vehicle tasks for inappropriate in-vehicle glancing behaviors in any dynamic traffic scenario for which appropriate individual occlusion distances can be defined.

Critical Analysis on the NHTSA Acceptance Criteria for In-Vehicle Electronic Devices

We tested a commercial in-car navigation system prototype against the NHTSA criteria for acceptance testing of in-vehicle electronic devices, in order to see what types of in-car tasks fail the acceptance test and why. In addition, we studied the visual demands of the driving scenario recommended by NHTSA for task acceptance testing. In the light of the results, NHTSA guidelines and acceptance criteria need to be further developed. In particular visual demands of the driving scenario and for different simulators need to be standardized in order to enable fair testing and comparable test results. We suggest the visual occlusion method for finding a driving scenario that corresponds better with real-life driving in visual demands as well as for standardizing the visual demands of the scenario when applied to different driving simulators. Furthermore, the acceptance criteria need to be re-evaluated. Especially the TEORT limits applicability to a variety of test tasks needs to be validated and exceptions for certain task types considered. The utility of the average glance duration criterion should be reconsidered.

On the Visual Distraction Effects of Audio-Visual Route Guidance

This is the first controlled quantitative analysis on the visual distraction effects of audio-visual route guidance in simulated, but ecologically realistic driving scenarios with dynamic maneuvers and self-controlled speed (N = 24). The audio-visual route guidance system under testing passed the set verification criteria, which was based on drivers preferred occlusion distances on the test routes. There were no significant effects of an upcoming maneuver instruction location (up, down) on the in-car display on any metric or on the experienced workload. The drivers median occlusion distances correlated significantly with median in-car glance distances. There was no correlation between drivers median occlusion distance and intolerance of uncertainty but significant inverse correlations between occlusion distances and age as well as driving experience were found. The findings suggest that the visual distraction effects of audio-visual route guidance are low and provide general support for the proposed testing method.

Context-sensitive distraction warnings - Effects on drivers' visual behavior and acceptance

In this study, we investigated the effects of context-sensitive distraction warnings on drivers in-car glance behaviors and acceptance. The studied prototype warning application functions on a smart phone. The novelty of the application is its proactive and context-sensitive approach to the adjustment of warning thresholds according to the estimated visual demands of the driving situation ahead. In our study, novice and experienced drivers conducted in-car tasks with a smart phone on a test track with and without the warnings. The application gave a warning if the drivers gaze was recognized to remain on the smart phone over a situation-specific threshold time, or if the driver was approaching a high-demand part of the track (an intersection or a tight curve). Glance metrics indicated a significant increasing effect of the warnings on glance time on road while multitasking. The effect varied between 5% and 30% increase depending on the in-car task. A text message reading task was the most visually demanding activity and indicated the greatest effect of the warnings on glance time on road. Driving experience did not have an effect on the efficiency of the warnings. The proposed gaze tracking with current smart phone technology proved to be highly unreliable in varying lighting conditions. However, the findings suggest that location-based proactive distraction warnings of high-demanding driving situations ahead could help all drivers in overcoming the inability to evaluate situational demands while interacting with complex in-car tasks and to place more attention on the road. Furthermore, survey results indicate that it is possible to achieve high levels of trust, perceived usefulness, and acceptance with these kinds of context-sensitive distraction warnings for drivers. Context-sensitive distraction warnings had a positive effect on drivers behaviors.The warnings significantly increased glance time on road, especially while reading a text message.The level of driving experience did not seem to affect the efficiency of the warnings.Location-based warnings worked more reliably than glance duration based warnings.The context-sensitive warning application was well accepted by the drivers.

Naturalistic study on the usage of smartphone applications among Finnish drivers

We present results from a naturalistic study that tracked how Finnish drivers use their smartphones while on the move. We monitored 30 heavy in-car smartphone users in Finland during June-September 2016, recording the times that they used their phones, the application used at the time of touch (calls excluded), the location and driving speed. Touches per time unit were used as a proxy for estimating visual-manual distraction due to visual-manual tasks. Our data set allows the determining of whether drivers use their phones differently on varying road types (highway, main road, local rural road, urban road). We found that the road type has an effect on phone use but the effect is contrary to what we expected. Drivers produced more touches per hour on urban roads, yet the use instances tend to be shorter than on the highway or main roads. We also collected statistics on the applications that were used. By far the highest overall rankings in the number of drivers using, number of uses, and duration per use instance was associated with the WhatsApp messaging service. One instance of WhatsApp use had a median of 8 touches, and had a median duration of 35u202fs. In contrast, navigation application use included a median of 3 touches and lasted for 11u202fs. The findings suggest that the Finnish smartphone heavy-users do not decrease their phone use when the demands of the traffic conditions increase and that the greatest risk from smartphone use may be currently caused by messaging applications.

Feasibility study for a nanosatellite-based instrument for in-situ measurements of radio noise

The radio environment on the earth is heavily affected by manmade sources such as radio transmissions, radars, and the like. The effect is particularly strong at MF frequencies and below, since the signals can propagate large distances via ionospheric bounce. Terrestrial magnetometer measurements have long been used to predict the Kp index, which is related to radio transmission at these ranges. Space weather measurements and models can also predict propagation of MF signals on the ground.