Biomedical subjects

David Shinar

Publications and source records attributed to David Shinar.

12 recordsLinked to original sources

PubMed2006

Ergonomic guidelines for traffic sign design increase sign comprehension.

OBJECTIVE: This research directly tests the relationship between comprehension probability of highway signs and the extent to which they comply with three ergonomic principles of design: sign-content compatibility, familiarity, and standardization. BACKGROUND: A recent study that evaluated comprehension of traffic signs in four different countries showed that comprehension level varies widely and is apparently related to the extent that the sign's design incorporates ergonomic guidelines for good design (D. Shinar, R. E. Dewar, H. Summala, and L. Zakowska 2003). METHOD: Participants were presented with 30 signs and asked to describe each sign's meaning. They then evaluated each sign in terms of each of three ergonomic principles. In addition, a group of human factors/ergonomics experts evaluated each sign on its standardization and compatibility. RESULTS: There were high correlations between the ratings of the students and the ratings of the experts on compatibility (rho = .94) and on standardization (rho = .84), validating the use of the students' evaluations of the signs on these variables. There was a great variability in signs' comprehension and high and statistically significant correlations between the comprehension level of each sign and the extent to which it complied with compatibility (R = .76), familiarity (R = .89), and standardization (R = .88) principles. CONCLUSIONS: The more signs conform to universal ergonomic principles of good design, the more likely they are to be comprehended by drivers of different cultural backgrounds. APPLICATION: Sign design should be guided by established ergonomics principles to enhance comprehension, especially for drivers who have not had any prior encounters with specific signs.

Adult↗

PubMed2005

Effects of practice, age, and task demands, on interference from a phone task while driving.

Experimental research on the effects of cellular phone conversations on driving indicates that the phone task interferes with many driving-related functions, especially with older drivers. Unfortunately in past research (1) the dual task conditions were not repeated in order to test for learning, (2) the 'phone tasks' were not representative of real conversations, and (3) most often both the driving and the phone tasks were experimenter-paced. In real driving drivers learn to time-share various tasks, they can pace their driving to accommodate the demands of a phone conversation, and they can even partially pace the phone conversation to accommodate the driving demands. The present study was designed to better simulate real driving conditions by providing a simulated driving environment with repeated experiences of driving while carrying two different hands-free 'phone' tasks with different proximities to real conversations. In the course of five sessions of driving and using the phone, there was a learning effect on most of the driving measures. In addition, the interference from the phone task on many of the driving tasks diminished over time as expected. Finally, the interference effects were greater when the phone task was the often-used artificial math operations task than when it was an emotionally involving conversation, when the driving demands were greater, and when the drivers were older. Thus, the deleterious effects of conversing on the phone are very real initially, but may not be as severe with continued practice at the dual task, especially for drivers who are not old.

Adolescent↗

PubMed2005

Drug identification performance on the basis of observable signs and symptoms.

A double blind study was performed to evaluate the ability of trained police officers to detect drug impairments and to identify the type of drug responsible for the impairment, on the basis of observed symptoms and psychophysical measurements of performance alone. The officers were not allowed to interview the subjects, and their conclusions were based solely on observable signs and symptoms on systematically measured vital signs, and on standardized sobriety tests of motor coordination. Results showed that with this partial information, the officers are able to detect drug impairment at better-than-chance levels with a sensitivity (correct detection of impairments) of 72%, but with a specificity of 43% (false alarm rate of 57%). Furthermore, the association between drug ingestion and identification of the specific impairing drug category was not very high, with sensitivities ranging from a low of 10% for amphetamine to a high of 49% for cannabis. Based on both sensitivity and specificity, drug identification was best for alprazolam impairment, noticeably poorer for cannabis and codeine impairment, and no better than chance for amphetamine impairment. Performance could have been improved if the officers were to list the two most probable impairing drugs (rather than limit their decision to only one), and if they were more consistent in their interpretation of observable signs and symptoms.

Accidents, Traffic↗

PubMed2005

Modeling drug detection and diagnosis with the 'drug evaluation and classification program'.

In this study, we propose formal models and algorithms to detect drug impairment and identify the impairing drug type, on the basis of data obtained by a Drug Evaluation and Classification (DEC) investigation. The DEC program relies on measurements of vital signs and observable signs and symptoms. A formal model, based on data collected by police officers trained to detect and identify drug impairments, yielded sensitivity levels greater than 60% and specificity levels greater than 90% for impairments caused by cannabis, alprazolam, and amphetamine. For codeine, with a specificity of nearly 90% the sensitivity was only 20%. Using logistic regression, the formal model was much more accurate than the trained officers in identifying impairments from cannabis, alprazolam, and amphetamine. Both the formal model and the officers were quite poor in identifying codeine impairment. In conclusion, the joint application of the DECP procedures with the formal model is useful for drug detection and identification.

Accidents, Traffic↗

PubMed2004

Aggressive driving: an observational study of driver, vehicle, and situational variables.

Over 2000 aggressive driving behaviors were observed over a total of 72 h at six different sites. The behaviors selected for observation were those that are commonly included in "aggressive driving" lists, and they consisted of honking, cutting across one or more lanes in front of other vehicles, and passing on the shoulders. In addition, an exposure sample of 7200 drivers were also observed at the same times and places. Relative risks (RRs) and odds ratios (ODs) were calculated to show the relative likelihood that different drivers under different conditions will commit aggressive behaviors. The rate of aggressive actions observed in this study decreased from the most frequent behavior of cutting across a single lane, through honking, and to the least frequent behaviors of cutting across multiple lanes and passing on the shoulders. Relative to their proportion in the driving population, men were more likely than women to commit aggressive actions, and the differences increased as the severity of the action increased. Drivers who were 45 years old or older were less likely to drive aggressively than younger ones. The presence of passengers was associated with a slight but consistent reduction in aggressive driving of all types; especially honking at other drivers. There was a strong linear association between congestion and the frequency of aggressive behaviors, but it was due to the number of drivers on the road. However, when the value of time was high (as in rush hours), the likelihood of aggressive driving--after adjusting for the number of drivers on the road--was higher than when the value of time was low (during the non-rush weekday or weekend hours). The results have implications for driver behavior modifications and for environmental design.

Adult↗

PubMed2004

Imperfect in-vehicle collision avoidance warning systems can aid drivers.

An experiment was conducted to determine the effects of an in-vehicle collision avoidance warning system (IVCAWS) on driver performance. A driving simulator was driven by 135 licensed drivers. Of these, 120 received alerts from the IVCAWS when their headway to a lead car was less than 2 s, and the other 15 (the control group) received no alerts. Drivers received varied alert interfaces: auditory, visual, and multimodal. The system had varied levels of reliability, determined by both false alarm rate and failure of the IVCAWS to alert to short headway. Results indicated that the IVCAWS led to safer (longer) headway maintenance. High false alarm rates induced drivers to slow down unnecessarily; large numbers of missed alerts did not have any significant impact on drivers. Driver acceptance of the system was mixed. Interface played a role in driver reliance on the system, with the multimodal interfaces generating least reliance. Actual or potential applications of this research include IVCAWS interface selection for greater system efficacy and user acceptance and the advisability of implementation, even of imperfect systems, for drivers who seek to maintain a safer headway.

Accidents, Traffic↗

PubMed2004

Synchronization of traffic signals as a means of reducing red-light running.

The goal of this study was to determine if traffic signals that are synchronized along a route are associated with fewer red-light violations than traffic signals that are not synchronized. A total 3600 cycles of traffic signals at 12 intersections along 2 major urban arteries were observed. Synchronized intersections were effective in reducing the likelihood of red-light running (RLR) by (a) providing fewer opportunities than nonsynchronized intersections for RLR and (b) having a lower rate of RLR relative to the number of opportunities. After adjustment for the number of opportunities, the odds of entering the intersections in red in synchronized intersections were nearly 1/7 the odds of RLR in nonsynchronized intersections. Congestion reduced the effectiveness of synchronized intersections relative to nonsynchronized intersections. Male drivers were slightly more likely to run red lights than female drivers, and the effects of synchronization were fairly constant across age, gender, and the presence or absence of passengers. Actual or potential applications of this research involve signal synchronization to reduce aggressive driving in general and RLR in particular.

Accidents, Traffic↗

PubMed2003

Traffic sign symbol comprehension: a cross-cultural study.

The objective of this study was to evaluate the comprehension levels of highway traffic sign symbols used in different countries, to identify underlying rules that affect comprehension levels, and recommend approaches to deal with the problem. The need for such an evaluation was based on today's travel culture where people are often licensed in one country and then drive--without any further training--in another country. We compared the comprehension levels of different traffic sign symbols in four countries with moderate to high levels of motorization: Canada, Finland, Israel, and Poland. Five different driver populations were sampled in each country: novice drivers, college students, tourists, problem drivers, and older drivers. There were large differences in comprehension among specific sign messages, different countries, and different driver populations. Signs were comprehended best when they were consistent with general ergonomic guidelines for display design as they relate to spatial compatibility, conceptual compatibility, physical representation, familiarity, and standardization. Illustrations of compliance with these principles and violations of these principles are presented, and their implication for traffic safety are discussed. Specific recommendations for sign design that is compliant with ergonomic principles, and for greater international cooperation in sign symbol design are made.

Accidents, Traffic↗

PubMed2003

New alternative methods of analyzing human behavior in cued target acquisition.

Target acquisition tasks in natural environments are often augmented by cuing systems that advise human observers during the decision process. With present technological limitations, cuing systems are imperfect, so the question arises whether cuing aids should be implemented under all conditions. We examined target acquisition performance under different levels of task complexity and cuing system reliability. We introduce here two new methods to help define observer behavior trends in cued target acquisition: a quantitative measure of observer search behavior in a temporal sense and a measure of the extent of observer reliance on the cue. We found that observer reliance on the cue correlated with task difficulty and the perceived reliability of the cue. Cuing was generally helpful in complex tasks, whereas cuing reduced performance in easy tasks. Consequently, cuing systems should be implemented only when the task is difficult enough to warrant the intrusion of a cue into the task. Actual or potential applications of this research include the design and implementation of imperfect automated aids dealing with augmented reality.

Adult↗

PubMed2002

Effects of uncertainty, transmission type, driver age and gender on brake reaction and movement time.

PROBLEM: Braking time (BT) is a critical component in safe driving, and various approaches have been applied to minimize it. This study analyzed the components of BT in order to assess the effects of age, gender, vehicle transmission type, and event uncertainty, on its two primary components, perception-reaction time and brake-movement time. METHOD: Perception-reaction time and brake-movement time were measured at the onset of lights for 72 subjects in a simulator. The six experimental conditions were three levels of uncertainty conditions (none, some, and some + false alarms) and two types of transmission (manual and automatic). The 72 subjects, half male and half female, were further divided into three age groups (mean of 23, 30, and 62 years). Each subject had 10 trials in each of the three levels of uncertainty conditions. RESULTS: Transmission type did not significantly affect either perception-reaction time or brake-movement time. Perception-reaction time increased significantly from 0.32 to 0.42 s (P < .05) as uncertainty increased but brake-movement time did not change. Perception-reaction time increased (from 0.35 to 0.43 s) with age but brake-movement time did not change with age. Gender did not affect perception-reaction time but did affect brake-movement time (males 0.19 s vs. females 0.16 s). IMPACT ON INDUSTRY: At 90 km/h, a car travels 0.25 m in 0.01 s. Consequently, even such small effects multiplied by millions of vehicle-kilometers can contribute to significant savings in lives and damages.

Adolescent↗

PubMed2002

Headway feedback improves intervehicular distance: a field study.

The effectiveness of a headway measuring and recording device was evaluated in terms of its ability to increase drivers' car-following distance. Forty-three drivers first drove for approximately 3 weeks without headway feedback and then for approximately 3 more weeks with immediate time headway (THW) feedback. Whenever the THW decreased to 1.2 s or less a red warning light came on, and whenever the THW decreased further to 0.8 s or less a buzzer was also sounded. The results showed that prior to receiving THW information,drivers drove at shorter headways than after they received that information. The effect of the feedback was to reduce the time spent in short headways (< or = 0.8 s) by approximately 25% (from 20% to 15% of the time) and to increase the time spent in safer longer headways (>1.2 s) by approximately 20% (from 57% to 65% of the time). The effect was similar for younger and older drivers, for male and female drivers, for urban and highway speeds, and for daytime and nighttime driving. An immediate application of these findings is to install headway feedback displays to drivers so that they may maintain safer headway distances than they do currently.

Acceleration↗

PubMed2002

Effects of an in-vehicle collision avoidance warning system on short- and long-term driving performance.

Many new in-vehicle systems focus on accident prevention by facilitating the driving task. One such driving aid is an in-vehicle collision avoidance warning system (IVCAWS), used to alert the driver to an impending collision. Our study evaluated the effects of an imperfect IVCAWS both on driver headway maintenance and on driver behavior in response to warning system errors. Our results showed that drivers tend to overestimate their headway and consequently drive with short and potentially dangerous headways, and that IVCAWSs are a useful tool for educating drivers to estimate headway more accurately. Moreover, our study showed that after a relatively short exposure to the system, drivers were able to maintain longer and safer headways for at least six months. The practical implications of these results are that the use of an IVCAWS should be considered for inclusion in driver education and training programs.

Accidents, Traffic↗