No abstract

Early research on gaze patterns during human locomotion indicated that pedestrians tend to focus their gaze on the path 2 – 3 m ahead. More recent research in this area has utilized eye tracking technology to empirically assess eye movements during navigation in naturalistic environments. A similar approach to understanding personal injuries resulting in civil lawsuits has potential utility in the field of forensic human factors. The present study was conducted in the context of gathering empirical data to support expert opinions in a premises liability civil suit. Using a mobile head-mounted eye tracker, the gaze patterns of five individuals was assessed as they walked two paths covering the area where the plaintiff in the subject suit was injured. The results of this analysis indicated that, consistent with previous research, participants fixated the path ahead. Additionally, the duration of fixations on their final destination tended to be longer than fixations on other objects or areas in the forward view. The present study demonstrates the utility of empirical analysis of conditions surrounding a personal injury using eye tracking technology.

The large majority of traffic crashes involving vulnerable road users such as pedestrians and bicyclists occur when ambient illumination levels are reduced. The difficulty drivers face in recognizing the presence of these road users in the darkness can be attributed to the selective degradation of foveal visual functions, which support a driver’s ability to detect and identify the presence of potential hazards and other objects in the environment. Clothing worn by pedestrians and bicyclists can contribute to their conspicuity to oncoming drivers; extensive research has demonstrated that dark-clothing-clad pedestrians are often recognized at dangerously short distances. Vehicle headlamps serve to illuminate the path ahead for drivers, particularly in the absence of artificial illumination along the roadway, in order to improve driver visibility in the dark. The twilight envelope is a means of determining the visibility distance afforded by headlamps. This approach to describing illumination was applied to the analysis of a traffic crash involving a vulnerable road user, providing insight into the driver’s visibility. Future research should address the relationship between the twilight envelope of vehicle headlamps and the distance at which drivers are able to recognize potential hazards such as pedestrians and bicyclists using those headlamps.

As the use of surveillance video at commercial properties becomes more prevalent, it is more likely an incident involving a personal injury will be captured on film. This provides a unique opportunity for Human Factors practitioners involved in forensic investigations to analyze the behavior of the individual prior to, during, and after the event in question. It also provides an opportunity to gather unique and objective data. The present work describes a case study of a slip and fall where surveillance video and onsite measurements were combined and analyzed to quantify a plaintiff’s gait pattern. Using this type of analysis, we were able to determine that the plaintiff was likely aware that the floor was slippery and adjusted her gait and behavior prior to the slip and fall incident.

Previous research suggests that while humans may be able to accurately assess whether or not slopes are traversable by foot, they are not as skilled at estimating the grade of slopes in degrees or percentages. This finding has practical implications for users of heavy power equipment who may operate such equipment on sloped terrain. Specifically, users who are unable to accurately estimate the grade of a slope where they plan to operate power equipment may put themselves in a dangerous position if the grade of such a slope exceeds the maximum permissible grade for safe equipment operation. In the present case a worker operated a power buggy on a slope that exceeded what was recommended by the manufacturer for operation. The operator was subsequently thrown from the equipment and was ultimate rendered a quadriplegic. We describe the method and results of a study conducted by our human factors personnel to determine the accuracy with which the "average" person is able to estimate and measure the grade of a slope. The implications of these findings for the present case are discussed. Additionally, the importance of adequate instructions, warnings, and feedback in the context of this unfortunate incident are discussed.