Forensic Human Factors Research Articles

Case Study: An Analysis of a Sidewalk Trip and Fall after Repair Utilizing Photograph Scaling

Often, forensic human factors consultants are hired to work on a case after the incident area is altered, repaired, or destroyed. Photographs documenting the original incident area are critical in determining the causes of the injured parties’ fall. The case presented in this paper involves a trip and fall that occurred on the sidewalk of a large apartment complex. A human factors consultant analyzed the incident sidewalk post repair and was able to estimate the original condition of the sidewalk through the use of photograph scaling. In addition to an analysis of the human factors surrounding an incident, photograph scaling can be a useful tool in estimating elevation changes and determining the causes in a post repair trip and fall incident.

Human Factors Investigation of Ejection from a Roller Coaster

The Human Factors Analysis and Classification System (HFACS) was used to evaluate a complex forensic case. The use of HFACS in forensic human factors is demonstrated via a case study of the death of a roller coaster rider ejected from his seat. The analysis revealed systemic factors for the fatality throughout the amusement park and ride manufacturer organizations. Such system analyses are needed to move park management and state investigators away from their narrow focus on rider behavior as causes of injury incidents, and address systemic factors to make amusement parks safer for guests.

Research-Based Forensic Analysis of a Vehicle Crash When Limited Information is Available: A Case Study

Forensic human factors analyses of personal injuries, including collisions, can be challenging when there is either limited evidence available and/or conflicting accounts of the events leading up to an incident. Gathering objective data under conditions representative of the incident in question can assist human factors practitioners in assessing the plausibility of certain facts and events, particularly in the aforementioned scenarios. The present work is part of the preliminary investigation of a collision in which little information was available about the incident. Data were gathered from nine participants to assist in determining a reasonable timeline of events leading up to impact between a disabled vehicle and a tractor trailer. The importance of reliance on such objective data as part of forensic analyses is discussed.

Human Factors Analysis of a Waiver: A Case Study

Case law has questioned the enforceability of waivers due to deficiencies in two categories: whether the defendant took reasonable steps to bring notice of the waiver and its contents to the attention of the plaintiff, and whether the waiver contained key design flaws. This report presents a case study on an accident at a recreational sports facility. An analysis was conducted on two versions of the facility’s waiver from a human factors perspective. The analysis reveals the application of forensic human factors concepts to waiver design and the influence that improperly designed waivers can have on sports and recreational injury lawsuits.

Forensic human factors and ergonomics: theory in practice

ABSTRACTThis lead article of the special issue on Forensic Human Factors and Ergonomics (guest edited by Michael S. Wogalter and Christopher B Mayhorn) introduces the readership to the topic then describes the five articles included.

Forensic human factors and ergonomics analysis of a trip and fall event in a parking lot

ABSTRACTBuilt (constructed) environments should have level surfaces to promote mobility and avoid injuries from trips and falls. Wheel stops (usually long concrete slabs with metal bolts to hold them in place) are sometimes placed in parking lots to limit and control how drivers position their vehicle in designated spaces. However, they present potential problems for pedestrians traversing through the area as they can cause trips and falls. A forensic human factors and ergonomics (HFE) analysis of a trip and fall event involving a wheel stop and its bolts in a parking lot is presented. The factors of visual obstruction, salience, attention, expectancy, and relevance issues are discussed. Additionally, an alternative analysis involving hazard control is presented. Potential solutions to limit risk to pedestrians and property owners are described.

Application of Affordance Theory to the Forensic Investigation of a Personal Injury

Early research on human perception of their environment by Gibson and colleagues revealed that observers are able to directly perceive objects in the context of their functional utility. As observers move about their environment, they are able to perceive visual, acoustic, and haptic changes that allow them to gather information about possible actions in their environment. This direct perception affordance theory has crucial relevance to the forensic analysis of personal injuries, including falls from heights. In the present case, a worker stepped through a suspended ceiling and suffered significant injuries as a result. We describe our application of the affordance theory to the analysis of this incident. Our analysis included determining the features of the environment that were perceivable to the plaintiff and how the presence of these features could have affected his ability to detect the undesirable fall-through affordance. The usefulness of the affordance theory in the context of forensic human factors is discussed.

Forensic Human Factors 101: Interactive Transportation and Product Liability Case Studies

This special joint session with shared interest from multiple technical groups (Forensics Professional Group, Product Design Technical Group, Safety Technical Group, and Surface Transportation Technical Group) provides audience members with an opportunity to conduct a forensic analysis of two cases involving human factors issues. The audience will form four groups in order to conduct their analysis of the behavior and actions of either the plaintiff or the defendant(s) involved in their assigned case. Participants in this session will be provided with information about the case they are analyzing, including descriptions of the circumstances surrounding the case and other factual information required to conduct a forensic analysis. One case will involve a collision between a commercial vehicle and a pedestrian, while the other will relate to the alleged failure of an air regulator utilized in diving. The teams will be asked to develop outlines of expert opinions relying on their knowledge, experience, and familiarity with applicable research. At the conclusion of the teams’ discussions, each team will briefly present the opinions reached by the team. To conclude the session, the audience will have the opportunity to discuss both cases and the value of human factors professionals in litigation. This session will emphasize the broad application of human factors and that forensic human factors work is accessible to a variety of practitioners.

Why We Withdrew from Our First Forensics Case

Work in the field of forensic human factors and biomechanics can be extremely difficult, especially for new professionals working on their first case. As such, it is not uncommon for new experts to take any case that they are retained on, regardless of the feasibility of the requests made of them. It is important, however, to maintain scientific and intellectual integrity on such cases, not only to establish a positive professional reputation but to ensure that future work in the field remains feasible. This paper addresses three central factors for withdrawal considerations (case facts, attorney-expert communications, and inter-professional interactions) that are illustrated using an example case in which a bridge collapse resulted in personal injury. The experts chose to withdraw from the case when the client attorney was unable to provide crucial data and materials that were promised at time of retention.

Amusement Park Guest Injured on a Water Ride: A human factors and biomechanics evaluation

When human factors and biomechanics professionals are retained to evaluate injury accidents, environmental design, hazard management and other relevant issues must be considered to develop opinions. This case study evaluates a forensic human factors and biomechanics case where a woman alleged that a water ride at an amusement park shot pressurized water into her ear, resulting in injuries. When evaluating the case, water droplet data was collected and relevant communication and system design factors were considered, along with the plaintiff’s personal knowledge and habits. This case illustrates when interactive environmental features result in a failure to warn and injuries.

The Utility of Mobile Eye Tracking Technology in the Forensic Analysis of Personal Injury

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.

A Forensic Human Factors Analysis of a Playground Designated for Special Needs Children

Human factors research has long addressed the issue of hazard management and the adequacy and effectiveness of product design and labeling. One issue that most professionals in the field would likely agree on is that manufacturers typically have the most information about hazards associated with their products and that they are in the best position to pass that information along to consumers. This case study regards a manufacturer who chose to provide multiple and conflicting labels when supplying product information to customers. The manufacturer failed to apply the appropriate label to its product and left that task to the consumer. A human factors analysis evaluated the design, labeling and relevant standards of care for playgrounds.

Falling from Airstairs while Disembarking from a Commuter Plane

When performing forensic human factors analyses it is imperative to carefully evaluate plaintiff and defense claims to determine if they are consistent with theoretical research and science. This case study concerns a fall from airstairs by a woman who was disembarking an airplane. At face value, the circumstances seemed valid enough that the airline chose to settle with the plaintiff before any kind of expert evaluation was performed. However, when the plane manufacturer was countersued, it chose to hire a human factors expert. A human factors expert analysis revealed that the plaintiff’s description of the incident was inconsistent with the evidence. Also considered were safety factors of airstair and airplane design. This case highlights the importance of evaluating witness descriptions of an incident as part of a forensic human factors analysis.

Examples of How to Present Human Factors Testimony to the Trier of Fact

The forensic human factors specialist is an advocate, an advocate of our discipline’s value in determining the cause of accidents, errors, and system failure. It follows that when we appear before the trier of fact – be it judge, jury, or attorney – we want to effectively convey our opinions and their foundation. The purpose of this session is for four practitioners of forensic human factors to share methods of providing testimony that are readily understandable and helpful to the trier of fact. In addition, a practicing attorney will give her take on criteria and concerns in retaining a forensic human factors specialist.

Panel Discussion – Factors related to perceiving the relative speed of leading vehicles in high-speed rear-end crashes

Forensic human factors practitioners are often engaged to offer expert opinions in cases involving rear-end collisions. Such collisions represent approximately 25% of all automobile crashes and have done so for many years. The sad fact is that people run into the backs of slow moving or stopped vehicles with a low, but persistent probability. According to the 100-car study, the probability is 1 in 1.84 million miles traveled (Americans drive a total of about 3 trillion miles per year). A number of researchers have examined the circumstantial and perceptual issues related to rear-end crashes in an effort to understand why drivers have such a difficult time perceiving the relative speed of leading vehicles. Results from these studies are often cited in expert reports and testimony. In particular, the “looming threshold” established in these studies is sometimes used to establish the expectation of braking or steering responses. However, when reconstruction data are used to calculate looming thresholds, the values are usually much higher than those obtained in controlled studies. It is unclear whether these data represent the same phenomenon. The purpose of this panel discussion is to examine the breadth of data related to rear-end crashes and offer insight into the discrepancy between reconstruction and experimental results.

Looming Threshold Limits and Their Use in Forensic Practice

Rear-end collisions account for about one-third of all traffic crashes on a yearly basis. It has been apparent for some time that the key to perceiving a slower vehicle ahead of us as an imminent hazard, i.e., one requiring immediate action, is a sufficient rate of change of the visual angle of the lead vehicle. This is known as the “looming threshold”, among other things. A number of laboratory researchers have reported values of the looming threshold to be in the range of 0.003 radian/sec. Forensic practitioners routinely use elevated values of the looming threshold, e.g., 0.005-0.008, to account for the complexity of real-world driving tasks. However, only one source has used data from actual vehicle accidents to arrive at a looming threshold – and that value, 0.0275 rad/sec, is an order of magnitude larger than that derived from laboratory studies. In this study, we examine a much broader range of real-world accident data to obtain an estimate of the reasonable upper end of the looming threshold. The results show a range of 0.0397 to 0.0117 rad/sec, for presumed perception-reaction times (PRTs) of 0.75 and 2.0 seconds, respectively. We discuss the implications for forensic human factors analysis of rear-end crashes.

Ratings checklist for warnings: a prototype tool to aid experts in the adequacy evaluation of proposed or existing warnings

In the field of forensic human factors, experts are often called upon to assess and evaluate the adequacy of new or existing products' warnings or warnings systems. The usual goal of this evaluation is to arrive at a simple binary decision regarding the warning in question (i.e., does it "pass/fail", or is it "adequate/inadequate"). However, such a warning assessment process may in fact be quite complex and multidimensional in its execution. The existing warnings research literature has identified a fairly large number of warnings features or factors likely to have an impact on a given warning's effectiveness or adequacy. The tool addressed in this article is intended for use by a warnings expert (as opposed to one less knowledgeable and informed about complex warnings issues), and can serve as a reminder checklist to help ensure that the expert has taken into consideration the most relevant features or factors during such a warnings adequacy assessment.

Participation on Voluntary Committees for Standards and Codes by Forensic Practitioners - A Win-Win Combination

This alternative format session synthesizes the experiences of five, diverse, forensic human factors practitioners who have actively participated in widely varying voluntary committees for standards and codes and found similar benefits of performing this work. Although such work is typically non-compensated, actively participating on voluntary standards committees can benefit society by improving safety standards and codes and simultaneously benefit the forensic human factors professional through contacts and networking, increased knowledge, technical expertise, and professional credibility. A strong need exists for more human factors input on voluntary committees. It is the authors’ hope that sharing their individual experiences will persuade other forensic human factors practitioners to similarly join in this mutually beneficial volunteer work.

Cognitive Human Factors in Litigation

Seemingly simple acts can go terribly wrong. Sometimes they result in litigation. Forensic human factors based in cognitive science can reveal some limitations in human perception, decision making, and action and how the design of things can fail to accommodate our limitations. The case studies indicate how design or maintenance could have prevented the injury incidents.

Avoiding Misrepresentation in Forensic Human Factors

Every aspect of human factors consulting in litigation presents opportunities and challenges for acting in an ethical manner. This article discusses three types of misrepresentation that pose ethical problems: (1) disregarding information, (2) misrepresenting existing research, and (3) misrepresenting facts in a case. These examples are demonstrated in the context of three different lawsuits involving forensic human factors experts. The article concludes with a discussion of the role of the forensic expert to help reveal the truth, and a suggestion to revise the Human Factors and Ergonomics Society Code of Ethics.