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Conversation Effects on Driving: Neural Mechanisms Underlying Reaction Times to Visual Events
Get PDFOBJECTIVES The purpose of this study was to determine the behavioral and neural correlates of conversation effects on driving using the same visual event detection paradigm in brain imaging, behavioral testing, and closed-road driving experiments. METHODS The “load” paradigm (Young et al., 2005b) assessed the effects of conversation on visual event detection during simulated driving in behavioral labs, fMRI and MEG imaging centers, and actual driving on a closed road. Behavioral and imaging data were collected. The primary task was to depress a foot pedal in response to a small red light presented to the left or below the driving scene at unpredictable times. The secondary task was to engage in a conversation. The participant pressed a button to answer a ring tone, and then answered simple auditory questions such as “What is your birthdate?” fMRI and MEG data were analyzed to examine the neural substrates of driving with and without conversation. The correlation, reliability and repeatability across experimental settings were analyzed using statistical procedures such as random effect ANOVA and multivariate regression models with repeated measure adjustment. RESULTS The behavioral results from all sites demonstrated that conversation had a small but consistent increase in reaction time (about 70-200 ms) with no effect on miss rates compared to the “no conversation” baseline. The random effect ANOVA and adjusted regression models confirmed the conversation effect in all settings, with good reliability and repeatability. The fMRI results showed that conversation activated not only language-specific areas as expected, but also increased activation in fronto-parietal pathways engaged in sensory-motor integration, attention modulation, and decision execution (Young et al., 2005a). Results of MEG imaging showed that in the “no conversation” baseline, behavioral RT was inversely related to changes in MEG brain activity in the right superior parietal lobe: more modulation in brain activity in the 200-300 ms range after light onset resulted in shorter RTs, and less modulation in longer RTs. A similar relation to RT was also seen in brain activity in the visual cortex in the 85-90 ms interval after red light onset. Conversation again activated language-specific areas in the MEG study, and resulted in less modulation in the right parietal and visual regions (Bowyer et al., 2006). Accordingly, conversation tended to increase mean behavioral RT slightly (no conversation 926 ms; conversation 993 ms). Further experiments are required to determine if the reduction in modulation due to conversation arises from inhibition, interference, or a removal of facilitation from top-down attentional processes. CONCLUSIONS Conversation slightly increases visual event reaction times in laboratory and closed-road driving experiments compared to a no-conversation baseline, with little or no effect on miss rates. Common fMRI and MEG imaging findings revealed fronto-parietal and visual-auditory-motor networks associated with sensory-motor integration, decision-making, and attention modulation during a driving-like scenario. Conversation appears to contribute to increased reaction times by reducing brain modulation to visual events in the right superior parietal region and visual cortices. These experimental findings should not be interpreted as if conversation increases the rate of crashes in real-world driving when compared to baseline driving without real-world validation and comparison of reaction time effects from other in-vehicle tasks. REFERENCES Bowyer, S., Moran, J., Hsieh, L., Manoharan, A., Young R.A., Malladi, K., Yu, Y-J., Chiang, YR., Hersberger, R., Genik, R., & Tepley, N. (2006). MEG localization of neural mechanisms underlying reaction time to visual events while watching a driving video: Effects of conversation. International Congress Series: New Frontiers in Biomagnetism. Proceedings of the 15th International Conference on Biomagnetism. Vancouver, BC Canada, August 21-25. D. Cheyne, B. Ross, G. Stroink and H. Weinberg (Editors). Young, R.A., Hsieh, L., Graydon, F.X., Genik II, R., Benton, M.D., Green, C.C., Bowyer, S.M., Moran, J.E., & Tepley, N. (2005a). Mind-on-the-Drive: Real-time functional neuroimaging of cognitive brain mechanisms underlying driver performance and distraction. Human Factors in Driving, Telematics and Seating Comfort 2005, SP-1934. Society of Automotive Engineering, Warrendale, PA, April. Young, R.A., Aryal, B., Muresan, M., Ding, X., Oja, S., & Simpson, S. (2005b). Road-to-lab: Validation of the static load test for predicting on-road driving performance while using advanced in-vehicle information and communication devices. Proceedings of the Third International Driving Symposium on Human Factors in Driver Assessment, Training and Vehicle Design, Rockport, Maine, July
A Simple and Effective Display for Night Vision Systems
Get PDFThe next generation of automotive night vision systems will likely continue to display to the driver enhanced images of the forward driving scene. In some displays there may also be highlighting of pedestrians and animals, which has been argued to be the primary safety goal of night vision systems. We present here the method that was used to design a conceptual display for night vision systems. Although the primary focus of the method is on safety analysis, consideration is given to driver performance with the system, and exposure to alerts. It also addresses user acceptance and annoyance, distraction, and expected behavior adaptation. The resulting driver interface is a simple and potentially effective display for night vision systems. It consists of a pedestrian icon that indicates when there are pedestrians near the future path of the vehicle. An initial prototype of this night-vision DVI was tested on the road and showed promising results despite its simplicity. It improved pedestrian detection distance from 34 to 44 m and decreased the overall ratio of missed pedestrians from 13% to 5%, correspondingly. The improvement may be attributable to the icon alerting the driver to the presence of a pedestrian. In this experiment, the drivers were probably more alert to the possible presence of pedestrians than drivers in the real world, suggesting that the effect of the icon might be even larger in actual use
Multisensory Signal Detection: How Does Driving and IVIS Management Affect Performance?
No full textSignal detection was used as a ‘tertiary’ task to assess drivers’ ‘spare processing capacity’ during the performance of two in-vehicle information systems (IVIS). The main aims of the study were: a) to establish if performance on signal detection can be used to assess IVIS safety during driving and b) to determine whether signal modality is important for this assessment. Participants performed each IVIS (Phone or Count) during a driving simulation experiment. In addition to performing the driving and IVIS, participants were required to complete three detection tasks (DT): (i) a visual DT (ii) an auditory DT, and (iii) a tactile DT. Average reaction time to the DTs was found to increase by around 200ms when performed with the IVIS tasks. It can be argued that any significant increase in reaction time to the DTs is a good indicator of drivers’ reduced hazard perception/situation awareness, which might occur as a result of using in-car systems. No significant difference in performance was found between the various DTs, suggesting that performance relies on central attentional resources, and is not modality-specific. This affords some flexibility for assessing the safety of IVIS in different driving environments. For instance, an auditory DT might be used in field studies on a sunny day when bright light hinders detection of LEDs used in a visual version of the task. Similarly, the tactile version of the task might be useful for testing IVIS in a noisy driving environment
Just Noticeable Differences for Vehicle Rates of Closure
Get PDFThe goal for this research was to identify the just noticeable difference (JND) for vehicle rates of closure. In our attempt to identify the JND we used two traditional psychophysical methods. However, these procedures resulted aberrant relationships between rate of closure and percent correct. Both of the traditional procedures used a sequential presentation of a standard animation and a comparison animation. The final method used a change in the rate of closure within the animation. This method provided us with a JND of between 12.9 to 16.1 km/h (8 to 10 mph). Reasons for the aberrant findings using the traditional methods are discussed
Toward a Driving Competency Assessment Encouraging Elderly's Automobility: A French Point of View
Get PDFThe purpose of this paper is to suggest a methodology for approaching French elderly driver assessments. More precisely, the objective is to evaluate the impact of visual and cognitive declines in older drivers on real road driving performances. A case control study was conducted with 40 senior drivers (aged between 61 to 80 years old) recruited via their insurance company: 20 case volunteers who had caused 3 or more accidents during a three-year period and 20 control volunteers who had caused no accidents during the same period. The experiment consisted of non-driving laboratory tests, including visual and cognitive tests, and a driving assessment in a real traffic situation. Results showed that, compared to the control group, elderly drivers with a history of accidents, have poorer performance on the cognitive tests. Moreover, data from the multiple regression analysis showed that the two measures entering the model were Zazzo time and movement perception (age and group being controlled). Some considerations that shape construction of a driving assessment are discussed. We discuss the fact that such an approach can be used to estimate the driving skills of drivers, not to deliver an aptitude or inaptitude certificate, but to adapt the advice given to drivers
Age Related Decrements in Steering Control: The Effects of Landmark and Optical Flow Information
Get PDFThis study examined age related decrements in the use of optical flow and landmark information for the control of steering. Older and younger drivers viewed computer generated displays simulating vehicle motion through a random dot ground plane scene. The horizontal position of the driver was perturbed according a sum of sines function and the driver had to keep steering straight (resembling the task of steering a car on a gusty day). On half the trials, landmark information was presented by color coding one of the dots on the ground plane. Overall, older drivers showed greater steering error magnitude (RMS error) than younger drivers. Unlike the younger drivers, the older drivers showed no reduction in steering errors when landmark information was present. These results suggest that older drivers are more reliant on optical flow information for controlling a vehicle and have a reduced ability to use alternative sources of information, such as landmarks, for steering control
Assessing Driving Performance with Moderate Visual Field Loss
Get PDFThe minimum binocular horizontal field extent for driver licensingvaries widely between states in the USA. We examined the relationship betweenvisual field extent and open-road driving performance using a scoring method thatmeasured the quality of specific skills for a range of general driving maneuvers,as well as maneuvers that we expected to be difficult for people with restrictedfields. Twenty-eight current drivers with mild to moderate peripheral visual fieldrestrictions (123 ± 20°, V4e target) drove the 14-mile route. While most subjectswere scored as safe drivers, those with more restricted horizontal and verticalbinocular field extents showed significantly poorer skills in maneuvers for whicha wide field of vision is likely to be important (p ≤ 0.05): speed matching whenchanging lanes, and maintaining lane position and keeping to the path of the curvewhen driving around curves. Further studies using similar assessment methodswith drivers with more restricted fields are necessary to determine the minimumfield extent for safe driving
Simulator Performance vs. Neurophysiologic Monitoring: Which is More Relevant to Assess Driving Impairment?
Get PDFPreviously, we reported on circadian variation in driving simulator performance and neurophysiologic evidence of sleep intrusion into consciousness in a pilot study of healthy individuals. We have since expanded this “normative” sample and run a prospective comparison study with a sample of clinical patients reporting excessive daytime sleepiness (EDS) as a chief complaint. Thirty healthy adults (mean age of 31.3 ± 11.5) and 27 EDS patients (47.0 ± 13.7) with valid driver’s licenses were included. Subjects performed four intentionally soporific 30-minute driving simulations at two-hour intervals while undergoing continuous EEG monitoring for microsleep (MS) episodes. Measured variables included: subjective ratings of sleepiness and alertness prior to each drive, lane position accuracy, mean speed, speed deviation, mean reaction time (RT) to “virtual” wind gusts as well as off-road events, i.e., “crashes.” In comparing normative individuals and EDS patients, significant between-group differences were found between subjective ratings, RT, crashes and MS. Both groups showed a significant a tendency towards RT slowing during afternoon drives, with this circadian effect appearing most pronounced for EDS patients. Significant between-group differences were also found on subjective ratings of sleepiness and alertness, although diurnal fluctuation of subjective sleepiness ratings was significant only for the EDS group. Objective EEG MS monitoring demonstrated escalating sleep intrusion with repeated drives in both groups, but particularly for the EDS group. Total crash rates were three times higher in EDS patients, with an increasing trend towards crash-proneness in the late afternoon. In summary, we found significantly impaired performance on some, though not all, driving parameters for EDS patients. While increased crash rate may be the most dramatic of these, slowing of RT was the most statistically robust. EEG monitoring was able to document increased propensity towards MS episodes in patients with EDS, which we suggest is causative in creating this impairment. It remains unclear whether a neurophysiologic or simulator approach captures impairment due to sleepiness with greater sensitivity and specificity. A hybrid approach combining data from both sources may be optimal, and also could be integrated in commercial vehicle use. We suggest that the need for a more accurate hospitalbased screening tool for assessment of driving impairment due to sleep disorders remains an important issue for physicians and legislators dealing with driving competency
Steering Entropy Revisited
Get PDFDrivers aim to maintain their vehicle within a number of individualsituated safety margins. Safety margin violations are characterized by rapid strongcorrective steering. Steering entropy was introduced to quantify drivers’ efforts tomaintain their lateral safety margins. In the original steering entropy, severalcomputational assumptions were made. The objective is to scrutinize andmotivate these choices and exemplify the effects of deviations from these choiceswith data from a driver distraction study. The new optimized algorithm is shownto yield significances where a number of classical metrics fail to find anysignificance. Its sensitivity is attributed to the fact that a number of observedchanges in steering behavior all manifest in a widened steering prediction errordistribution which the algorithm picks up sensitively with its log-based weightingof prediction error outliers and its use of a prediction filter that is maximallysensitive to the spectral characteristics of the baseline data
Workload Changes in Teenaged Drivers Driving with Distractions
Get PDFWorkload refers to the amount of cognitive resources necessary toperform a task, and it can be manipulated by incorporating secondary tasks into aprimary task such as driving. The present study incorporated answering a phoneand removing a plastic bottle top into a driving task for teen drivers. Resultsshowed few performance differences between driving with and withoutdistractions, although subjective workload did increase for the drive that includeddistractions compared to the non-distraction drive. This indicates that teens maybe able to maintain driving performance while performing secondary tasks,although their workload appears to increase