How driving duration influences drivers' visual behaviors and fatigue awareness: a naturalistic truck driving test study

AbstractBackground: Commercial truck drivers stay behind the wheel for long hours. Fatigue is thus a major safety concern among such long distance travelling drivers.Objectives: Primarily, the study explored the effects of driving duration on commercial truck drivers’ visual features and fatigue awareness. It also examined the association between visual variables and subjective level of fatigue.Methods: Participants of the study were 36 commercial truck drivers. During the study, the participants were grouped into nine on the basis of the differences in their age and were made to participate in the naturalistic driving test. In the driving test, the participants were asked to finish 2h, 3h, and 4h continuous driving tasks. Ten visual indicators and self awareness of fatigue level of the drivers were recorded during the driving hours. One-way ANOVA and Pearson product-moment correlation were used to analyze each visual indicator’s variation by age groups over time, and its association with subjective level of fatigue.Results: The statistical analysis revealed that continuous driving duration had a significant effect on changes of visual indicators and self-reported fatigue level. After 2h of driving, both the average closure duration value and average subjective fatigue level changed significantly. After 4h of driving, other than the average number of saccades and average pupil diameter, all of the driver’s visual indicators had a significant change. In addition, the change of fatigue level is positively associated with the variation of pupil diameter, fixation duration, blink frequency, blink duration, and closure duration. On the other hand, the change of fatigue level was negatively related to number of fixations, search angle, number of saccade, saccade speed, and saccade amplitude.Conclusion: Driving duration has a significant effect on driver’s visual variation and fatigue level. For commercial truck drivers, traffic laws and regulations should strictly control the amount of their continuous driving time. Moreover, driving fatigue can also be evaluated through the change rate of driver’s visual indicators. Awareness of the rate of change in their driving fatigue level alerts drivers to the risk of fatigue and rest moment. [Ethiop. J. Health Dev. 2018;32(1):36-45

Convergent Evolution of Brain Morphology and Communication Modalities in Lizards

Animals communicate information within their environments via visual, chemical, auditory, and/or tactile modalities. The use of each modality is generally linked to particular brain regions, but it is not yet known whether the cellular morphology of neurons in these regions has evolved in association with the relative use of a modality. We investigated relationships between the behavioral use of communication modalities and neural morphologies in six lizard species. Two of these species (Anolis carolinensis and Leiocephalus carinatus) primarily use visual signals to communicate with conspecifics and detect potential prey, and two (Aspidoscelis gularis and Scincella lateralis) communicate and forage primarily using chemical signals. Two other species (Hemidactylus turcicus and Sceloporus olivaceus) use both visual and chemical signals. For each species, we performed behavioral observations and quantified rates of visual and chemical behaviors. We then cryosectioned brain tissues from 9-10 males of each species and measured the soma size and density of neurons in two brain regions associated with visual behaviors (the lateral geniculate nucleus and the nucleus rotundus) and one region associated with chemical behaviors (the nucleus sphericus). With analyses conducted in a phylogenetic context, we found that species that performed higher rates of visual displays had a denser lateral geniculate nucleus, and species that used a higher proportion of chemical displays had larger somas in the nucleus sphericus. These relationships suggest that neural morphologies in the brain have evolved convergently in species with similar communication behaviors

Subjective Sleepiness Dynamics Dataset (SSDD) Presentation: the Study of Two Scales Consistency

While the first references to the system of sleepiness assessment are associated with medical re-search and the study of the effects of drugs on sleep, currently subjective sleepiness assessment is widely used across fundamental and practically oriented studies. The Stanford Sleepiness Scale (SSS) and the Karolinska Sleepiness Scale (KSS) are often used as ground truth in sleepiness re-search. Only a few studies applied both scales and practically none aimed at studying their con-sistency and specific features. The present study is devoted to analyzing the dynamics and con-sistency of subjective sleepiness as measured by the KSS and the SSS in the adult population. A particular task of the paper is to present the Subjective Sleepiness Dynamics Dataset (SSDD) with the evening and morning dynamics of situational subjective sleepiness. A total of 208 adults took part in the experiment. The results of the study revealed that sleepiness generally increased from evening till night and was maximal at early morning. The SSS score appeared to be more sensitive to some factors (e.g., the presence of sleep problems). The SSS and KSS scores were strongly consistent with each other. The KSS showed a generally more even distribution than the SSS. SSDD continues to be collected, we are going to equalize the sample by sex, we are actively adding older people. We plan to collect a sample of 1,000 people. Currently SSDD contains a lot of in-formation that can be used for scientific research.Comment: 18 pages, 6 figures, 3 table

The effect of experience on the use of multimodal displays in a multitasking interaction

Theories and previous work suggest that performance while multitasking can benefit from the use of displays that employ multiple modalities. Studies often show benefits of these multimodal displays but not to the extent that theories of multimodal task-sharing might suggest. However, it is often the case that the studies investigating this effect give users at least one type of display that they are not accustomed to, often an auditory display, and compare their performance on these novel displays to a visual display, with which most people are familiar. This leaves a question open regarding the effects of longer-term experience with these multimodal displays. The current study investigated the effect of practice with multimodal displays, comparing two multimodal displays to a standard visuals-only display. Over the course of four sessions, participants practiced a list-searching secondary task on one of three display types (two auditory plus visual displays, and one visual-only display) while performing a visual-manual task. Measures of search-task and primary task performance along with workload, visual behaviors, and perceived performance were collected. Results of the study support previous work with regard to more visual time on the primary task for those using multimodal displays, and show that perceived helpfulness increased over time for those using the multimodal displays. However, the results also point to practice effects taking place almost equally across the conditions, which suggest that initial task-sharing behaviors seen with well-designed multimodal displays may not benefit as much from practice as hypothesized, or may require additional time to take hold. The results of the research are discussed regarding their use in research and applying multimodal displays in the real world as well as in how these results fit with theories of multimodal task-sharing.Ph.D

Can variations in visual behavior measures be good predictors of driver sleepiness? A real driving test study

<p><b>Objective</b>: The primary purpose of this study was to examine the association between variations in visual behavior measures and subjective sleepiness levels across age groups over time to determine a quantitative method of measuring drivers' sleepiness levels.</p> <p><b>Method</b>: A total of 128 volunteer drivers in 4 age groups were asked to finish 2-, 3-, and 4-h continuous driving tasks on expressways, during which the driver's fixation, saccade, and blink measures were recorded by an eye-tracking system and the subjective sleepiness level was measured through the Stanford Sleepiness Scale. Two-way repeated measures analysis of variance was then used to examine the change in visual behavior measures across age groups over time and compare the interactive effects of these 2 factors on the dependent visual measures.</p> <p><b>Results</b>: Drivers' visual behavior measures and subjective sleepiness levels vary significantly over time but not across age groups. A statistically significant interaction between age group and driving duration was found in drivers' pupil diameter, deviation of search angle, saccade amplitude, blink frequency, blink duration, and closure duration. Additionally, change in a driver's subjective sleepiness level is positively or negatively associated with variation in visual behavior measures, and such relationships can be expressed in regression models for different period of driving duration.</p> <p><b>Conclusions</b>: Driving duration affects drivers' sleepiness significantly, so the amount of continuous driving time should be strictly controlled. Moreover, driving sleepiness can be quantified through the change rate of drivers' visual behavior measures to alert drivers of sleepiness risk and to encourage rest periods. These results provide insight into potential strategies for reducing and preventing traffic accidents and injuries.</p