The effect of auditory and visual distracters on the useful field of view: Implications for the driving task

PURPOSE. The driving environment is becoming increasingly complex, including both visual and auditory distractions within the in- vehicle and external driving environments. This study was designed to investigate the effect of visual and auditory distractions on a performance measure that has been shown to be related to driving safety, the useful field of view. METHODS. A laboratory study recorded the useful field of view in 28 young visually normal adults (mean 22.6 +/- 2.2 years). The useful field of view was measured in the presence and absence of visual distracters (of the same angular subtense as the target) and with three levels of auditory distraction (none, listening only, listening and responding). RESULTS. Central errors increased significantly (P < 0.05) in the presence of auditory but not visual distracters, while peripheral errors increased in the presence of both visual and auditory distracters. Peripheral errors increased with eccentricity and were greatest in the inferior region in the presence of distracters. CONCLUSIONS. Visual and auditory distracters reduce the extent of the useful field of view, and these effects are exacerbated in inferior and peripheral locations. This result has significant ramifications for road safety in an increasingly complex in-vehicle and driving environment.

An unexpected role for visual feedback in vehicle steering control

Some motor tasks can be completed, quite literally, with our eyes shut. Most people can touch their nose without looking or reach for an object after only a brief glance at its location. This distinction leads to one of the defining questions of movement control: is information gleaned prior to starting the movement sufficient to complete the task (open loop), or is feedback about the progress of the movement required (closed loop)? One task that has commanded considerable interest in the literature over the years is that of steering a vehicle, in particular lane-correction and lane-changing tasks. Recent work has suggested that this type of task can proceed in a fundamentally open loop manner [1 and 2], with feedback mainly serving to correct minor, accumulating errors. This paper reevaluates the conclusions of these studies by conducting a new set of experiments in a driving simulator. We demonstrate that, in fact, drivers rely on regular visual feedback, even during the well-practiced steering task of lane changing. Without feedback, drivers fail to initiate the return phase of the maneuver, resulting in systematic errors in final heading. The results provide new insight into the control of vehicle heading, suggesting that drivers employ a simple policy of “turn and see,” with only limited understanding of the relationship between steering angle and vehicle heading.

Initiation of evasive manoeuvres during self-motion: a test of three hypotheses

To understand performance of evasive and interceptive actions it is important to know how people decide when to initiate a movement - initiating at the 'right' moment is often essential for successful performance. It has been proposed that initiation is triggered when a perceptually derived quantity reaches an invariant criterion value. Candidate quantities include time-to-collision (TTC), distance, and rate of image expansion ( ROE), all of which have received empirical support. We studied initiation of an evasive manoeuvre in a computer-simulated steering task in which the observer was required to steer through a stationary visual environment and avoid colliding with an obstacle in their path. The results could not be explained by hypotheses which propose that evasive manoeuvre initiation is based on a fixed criterion value of TTC or distance. The overall pattern was, however, consistent with the use of a criterion ROE value. This was further tested by analyses designed to directly evaluate whether the ROE value used to initiate the response was the same across experimental conditions. Only two of the six participants showed evidence for using the ROE strategy.

Drivers' ratings of different components of their own driving skill: A greater illusion of superiority for skills that relate to accident involvement

Different components of driving skill relate to accident involvement in different ways. For instance, while hazard-perception skill has been found to predict accident involvement, vehicle-control skill has not. We found that drivers rated themselves superior to both their peers and the average driver on 18 components of driving skill (N = 181 respondents). These biases were greater for hazard-perception skills than for either vehicle-control skills or driving skill in general. Also, ratings of hazard-perception skill related to self-perceived safety after overall skill was controlled for. We suggest that although drivers appear to appreciate the role of hazard perception in safe driving, any safety benefit to be derived from this appreciation may be undermined by drivers' inflated opinions of their own hazard-perception skill. We also tested the relationship between illusory beliefs about driving skill and risk taking and looked at ways of manipulating drivers' illusory beliefs.

Risk taking from the participant's perspective: The case of driving and accident risk

Although perceived health risk plays a prominent role in theories of health behavior. its empirical role in risk taking is less clear. In Study 1 (N = 129), 2 measures of drivers' risk-taking behavior were found to be unrelated to self-estimates of accident concern but to be related to self-ratings of driving skill and the perceived thrill of driving. In Study 2 (N = 405), out of a wide range of potential influences, accident concern had the weakest relationship with risk taking. The authors concluded that although health risk is a key feature in many theories of health behavior and a central focus for researchers and policy makers, it may not be such a prominent factor for those actually taking the risk.

Signal detection theory in applied tasks: The case of hazard perception in driving

Fuzzy signal detection analysis can be a useful complementary technique to traditional signal detection theory analysis methods, particularly in applied settings. For example, traffic situations are better conceived as being on a continuum from no potential for hazard to high potential, rather than either having potential or not having potential. This study examined the relative contribution of sensitivity and response bias to explaining differences in the hazard perception performance of novices and experienced drivers, and the effect of a training manipulation. Novice drivers and experienced drivers were compared (N = 64). Half the novices received training, while the experienced drivers and half the novices remained untrained. Participants completed a hazard perception test and rated potential for hazard in occluded scenes. The response latency of participants to the hazard perception test replicated previous findings of experienced/novice differences and trained/untrained differences. Fuzzy signal detection analysis of both the hazard perception task and the occluded rating task suggested that response bias may be more central to hazard perception test performance than sensitivity, with trained and experienced drivers responding faster and with a more liberal bias than untrained novices. Implications for driver training and the hazard perception test are discussed.

Time-reversal test for stochastic quantum dynamics

The calculation of quantum dynamics is currently a central issue in theoretical physics, with diverse applications ranging from ultracold atomic Bose-Einstein condensates to condensed matter, biology, and even astrophysics. Here we demonstrate a conceptually simple method of determining the regime of validity of stochastic simulations of unitary quantum dynamics by employing a time-reversal test. We apply this test to a simulation of the evolution of a quantum anharmonic oscillator with up to 6.022×1023 (Avogadro's number) of particles. This system is realizable as a Bose-Einstein condensate in an optical lattice, for which the time-reversal procedure could be implemented experimentally.

Apparent insensitivity of the hotplate latency test for detection of antinociception following intraperitoneal, intravenous or intracerebroventricular M6G administration to rats

Although morphine-6-glucuronide (M6G) has been shown to be analgesically active, the relative involvement of spinal and supraspinal structures in mediating M6G's pain-relieving effects following central and systemic administration to rats is unclear. As the tail flick and hotplate latency tests are reported to quantify antinociception mediated primarily by spinal and supraspinal mechanisms respectively, these methods were used to determine the comparative apparent levels of antinociception (expressed as percentage maximum possible effect, % MPE) achieved after M6G or morphine administration. Following i.v. or i.p. M6G (1.9-5.4 mu mol) dosing or i.p. morphine (10 mu mol) dosing, high levels of antinociception (>50% MPE) were achieved using the tail flick test whereas base-line levels of antinociception were observed 30 sec later in the same rats using the hotplate test. By contrast, antinociception evoked by i.v. morphine (10 mu mol) exceeded 50% MPE using both the hotplate and tail flick tests although the apparent potency was approximately 2.5 times greater using the tail flick test. After i.c.v. dosing, M6G (0.22-3.3 nmol) was significantly (P < .05) more potent when assessed using the tail flick compared with the hotplate test. Taken together, these data strongly indicate that following central and systemic administration, M6G's antinociceptive effects are mediated primarily by spinal structures whereas both spinal and supraspinal mechanisms contribute to systemic morphine's antinociceptive effects.

The Modified Card Sorting Test: Test-retest stability and relationships with demographic variables in a healthy older adult sample

Objectives. To investigate the test-retest stability of a standardized version of Nelson's (1976) Modified Card Sorting Test (MCST) and its relationships with demographic variables in a sample of healthy older adults. Design. A standard card order and administration were devised for the MCST and administered to participants at an initial assessment, and again at a second session conducted a minimum of six months later in order to examine its test-retest stability. Participants were also administered the WAIS-R at initial assessment in order to provide a measure of psychometric intelligence. Methods. Thirty-six (24 female, 12 male) healthy older adults aged 52 to 77 years with mean education 12.42 years (SD = 3.53) completed the MCST on two occasions approximately 7.5 months (SD = 1.61) apart. Stability coefficients and test-retest differences were calculated for the range of scores. The effect of gender on MCST performance was examined. Correlations between MCST scores and age, education and WAIS-R IQs were also determined. Results. Stability coefficients ranged from .26 for the percent perseverative errors measure to .49 for the failure to maintain set measure. Several measures were significantly correlated with age, education and WAIS-R IQs, although no effect of gender on MCST performance was found. Conclusions. None of the stability coefficients reached the level required for clinical decision making. The results indicate that participants' age, education, and intelligence need to be considered when interpreting MCST performance. Normative studies of MCST performance as well as further studies with patients with executive dysfunction are needed.

Critical values for unit root and cointegration test statistics - the use of response surface equations

This note considers the value of surface response equations which can be used to calculate critical values for a range of unit root and cointegration tests popular in applied economic research.

International tourists and road safety in Australia: developing a national research and management programme

Motor vehicle crashes are the leading cause of injury death for international tourists. This makes road safety an important issue for tourism authorities. Unfortunately, as it is in other areas of tourist health, the common response from the travel and tourism industry is to remain silent about this problem and to leave any mishaps in the hands of insurers. At the same time, but for different reasons, international tourists are not usually targeted for road safety initiatives by transport authorities. Given that there are considerable 'hidden' costs associated with international tourists and motor vehicle crashes, the topic should be of concern to both tourism and transport groups. This paper examines issues concerned with driving in unfamiliar surroundings for international visitors in Australia, and proposes a national research and management programme to guide policy and planning in the area. (C) 1999 Elsevier Science Ltd. All rights reserved.

Dendritic cells: the driving force behind autoimmunity in rheumatoid arthritis?

Dendritic cells (DC) are likely to play a significant role in immune-mediated diseases such as autoimmunity and allergy. To date there are few treatments capable of inducing permanent remission in rheumatoid arthritis (RA) and elucidation of the role of DC may provide specific strategies for disease intervention. Dendritic cells have proven to be powerful tools for immunotherapy and investigations are under way to determine their clinical efficacy in transplantation and viral and tumour immunotherapy. The present review will focus on the current view of DC and their role in autoimmunity, in particular RA. Two possible roles for DC in the pathogenesis of RA will be proposed, based on recent advances in the field.

A test of competing explanations of compensation demanded

We find that prospect theory behavior is significantly more prevalent than utility theory behavior in experiments involving multiple, real items. In the experiments, subjects were endowed with three items and asked the minimum payments they required to be willing to return one, two, or three of them. Our key observation is that prospect theory implies concavity of compensation demanded, whereas utility theory implies convexity. We examine whether the compensation demanded is convex or concave in the number of items returned. (JEL C91).

Evolution of the genetic covariance between male and female components of mate recognition: An experimental test

The evolution of a positive genetic correlation between male and female components of mate recognition systems will result as a consequence of assortative mating and, in particular, is central to a number of theories of sexual selection. Although the existence of such genetic correlations has been investigated in a number of taxa, it has yet to be shown that such correlations evolve and whether they may evolve as rapidly as suggested by sexual selection models. In this study, I used a hybridization experiment to disrupt natural mate recognition systems and then observed the subsequent evolutionary dynamics of the genetic correlation between male and female components for 56 generations in hybrids between Drosophila serrata and Drosophila birchii. The genetic correlation between male and female components evolved from 0.388 at generation 5 to 1.017 at generation 37 and then declined to -0.040 after a further 19 generations. These results indicated that the genetic basis of the mate recognition system in the hybrid populations evolved rapidly. The initial rapid increase in the genetic correlation was consistent with the classic assumption that male and female components will coevolve under sexual selection. The subsequent decline in genetic correlation may be attributable to the fixation of major genes or, alternatively, may be a result of a cyclic evolutionary change in mate recognition.