Urs Maag

Individual Differences in Trajectory of Intellectual Development Over 45 Years of Adulthood

The hypothesis that individual differences in adult intellectual development reflect variation in life context and personality was examined in 132 World War II (WWII) veterans. Intelligence data from the Canadian Army M Test were available for 3 occasions, WWII, 1984-1986 (Int85), and 1989-1991 (Int90). Performance declined over the 45 years on 5 subtests but improved on the 6th, Vocabulary. Correlations between WWII and Int90 scores showed considerable stability of individual differences in intelligence over 45 years. Younger age predicted less decline over 45 years on all subtests; a more engaged lifestyle predicted less decline on most subtests, and better health and greater introversion predicted less decline on some subtests. Predictors of change since Int85 were similar to those for the whole period. Implications for theories of adult intellectual development are discussed.

Everyday activity parameters and competence in older adults.

Parameters of everyday activities in relation to cognitive, social, and emotional competence were examined in 2 studies. The parameters included frequency, difficulty, importance, intentions for future activities, changes in past activities, and ability of performance. The challenge hypothesis, in which performance of optional activities experienced as moderately difficult is associated with greatest well-being, was also tested. Two samples of older adults completed a life history interview and measures of psychological functioning. Parameters of activities necessary for maintaining an independent engaged lifestyle were measured by the Everyday Activities Questionnaire. In both studies, competence variables helped explain activity parameters independently of age and demographic variables. There was no support for the challenge hypothesis in either study.

The Wechsler subtests in mild organic brain damage associated with folate deficiency.

Forty-nine patients with low serum and cerebrospinal fluid folate levels completed the Ottawa-Wechsler Scale after 7-11 months of folate supplementation (10 mg daily). Twelve patients exhibited major neurological symptoms, while 37 patients displayed depression and minor neurological signs. After folate therapy, Verbal, Performance and Full Wechsler scores were significantly improved (P less than 0.001). The order of improvement in scores on the Wechsler subtests (from the statistically most significant to the least as measured by the t-statistics) was: Block Design, Digit Symbol, Similarities, Picture Completion, Picture Arrangement, Arithmetic, Object Assembly, Digit Span, Information, and Comprehension.

Neck injuries among belted and unbelted occupants of the front seat of cars

This article, part of a recently completed research project on safety belts, presents results on neck injuries. A total of 3927 injured front-seat occupants (drivers and passengers) involved in two-car crashes were studied. Among them, 725 sustained neck sprains (ICD-9 code 847.0); some of them may have sustained other injuries as well. The more serious injuries to the cervical spine were more prevalent among the unbelted occupants. Neck sprains were relatively more numerous among belted occupants compared with unbelted ones, with a relative risk estimate of 1.68. Similar results hold also for subsets of the data on different types of collisions; the relative risks ranged from 1.39 to 2.42. A log linear model was constructed for the odds ratio (neck sprain vs. no neck sprain) taking into account the following factors: (1) seatbelt use, (2) direction of impact, (3) authorized speed limit, and (4) vehicle weight. The resulting relative risk estimate (belted vs. unbelted) became 1.58. The results raise questions about seatbelts and their protection against neck sprains.

The Role of Driver Education in the Licensing Process in Quebec

Problem. In many jurisdictions, driver education (DE) graduates, compared to non-graduates, are granted a time-discount that allows them to drive unsupervised several months earlier, despite little evidence of a safety benefit and consistent evidence of increased crash risk. Confounding factors may be threatening the validity of DE evaluations. A theoretical framework called the “licensing process” (LP) is proposed to identify and explore potential confounding factors in DE evaluations. Method. Prospective study data on a cohort of 1804 novice drivers 16 to 19 years of age of both sexes are analyzed in relation to the LP framework. These data derive from two sources that were linked together: an extensive questionnaire on learning methods, risk-taking, and lifestyles, and government records on exam performance, violations, and crashes. Results. Violation and crash records are not associated with DE attendance. DE attendance is associated with younger ages, greater financial support from family, and fewer hours of supervised driving practice with a learners permit. For both sexes, more hours of supervised driving practice with a learners permit is associated with increased crash risk. Most participants, particularly males under 19 years of age, attended DE partly or entirely to save time or money; these motivations are associated with higher violation and crash rates. Discussion. DE evaluations need to identify and control for potential confounding factors. Research is needed to understand the associations between increased crash risk and potential confounding factors like motivation to attend DE and hours of supervised driving practice.

Exposure for different license categories through a phone survey: Validity and feasibility studies☆

This paper presents: (i) an operational definition of risk exposure, (ii) a questionnaire developed to measure exposure, (iii) validity studies of estimates of the distance traveled and time spent driving for different permit holder categories, and (iv) a feasibility study for a telephone survey on exposure. Results show that long-distance truck drivers from one company studied estimated accurately their distance driven on the last worked day; Montreal Urban Community Transport Commission bus drivers estimated well their time behind the wheel; while a convenience sample of private car drivers (coworkers and friends) estimated well their previous week distance and time on the road. Phone surveys appear to be an efficient and cost-effective method for risk exposure data collection.

Analysis of the Economic Impact of Medical and Optometric Driving Standards on Costs Incured by Trucking Firms and on the Social Costs of Traffic Accidents

Recent studies do not agree on the possible relationship between medical conditions and traffic safety; most of them do not control for exposure factors. In this study, we estimate the effect of different medical conditions (namely diabetes, high blood pressure, coronary disease and monocular vision) on the distribution of accidents of truck drivers. Our data and our model permit the simultaneous control for age, medical conditions and other characteristics of the truck drivers; exposure factors measured by hours, kilometers, and qualitative factors; and of the circumstances surrounding accidents described in police reports.

Road crashes and injuries in Quebec (1974): patterns among many variables

Data on 1008 Quebec road victims obtained from linkage of governmental records have led to different types of analyses. This article presents an application of correspondence analysis to these data. We have chosen one example with its specific results showing expected associations between variables and new, unexpected associations which are plausible. The resulting patterns indicate a clear distinction between hospitalized and non-hospitalized victims and between a rural and an urban type of road crash. This multidimensional approach gives an overall picture of the patterns among the variables studied, indicating which subsets of variables might be investigated further.

An Evaluation of the Effects on Crashes of the 1991 Legislative Reform on New Licensees in Quebec

Any learning task, particularly a complex one such as driving an automobile, needs time and experience to arrive at a good performance.