Two experiments are reported in which younger and older adults practiced rapid aimed limb movements toward a visible target region. Ss were instructed to make the movements as rapidly and as accurately as possible. Kinematic details of the movements were examined to assess the differences in component submovements between the 2 groups and to identify changes in the movements due to practice. The results revealed that older Ss produced initial ballistic submovements that had the same duration but traveled less far than those of younger Ss. Additionally, older Ss produced corrective secondary submovements that were longer in both duration and distance than those of the younger subjects. With practice, younger Ss modified their submovements, but older Ss did not modify theirs even after extensive practice on the task. The results show that the mechanisms underlying movements of older adults are qualitatively different from those in younger adults.
The attitudes toward National Health Insurance held by 126 second year dental students and 108 second year dental hygiene students enrolled in the state of Wisconsin, U.S.A., were measured and compared with the attitudes held by practicing dentists in the U.S.A. Although some similarities were noted, marked differences were revealed, with students, generally, preferring broader coverage and more government involvement than practicing dentists. There is virtually no published data in this area, and more research is needed, as the success or failure of any National Health Insurance plan depends critically on the attitudes of both health care providers and those studying to become health care providers.
This project was undertaken from July 1999 to August 2000 to identify the status of extramural programming (that is, a program that has undergraduate dental students providing any aspect of dental care to individuals in settings outside the main clinical facility of the school) in North American dental schools. A survey instrument was mailed to all United States and Canadian dental schools concerning student involvement in extramural programming. The response rate was 79.7 percent. Of the schools responding, 3.9 percent did not offer extramural programming. The type of extramural sites, the percentage of schools offering each type of site, and the mean number of weeks students are at each site were as follows: hospital clinics—71 percent, 2.5 weeks; public health clinics—65 percent, 6 weeks; schools and day care centers—49, 1.7 weeks; private dental offices—37 percent, 2 weeks; and “other” —29 percent, 2.5 weeks. The average number of weeks spent at extramural site(s) per class was: freshman 1.9 weeks (SD=4.3); sophomores 2.3 weeks (SD=4.2); juniors 2.6 weeks (SD=1.9); and seniors 5.3 weeks (SD=6.7). Of total student time in extramural programming, 43.3 percent was spent delivering basic clinical services, 24.4 percent comprehensive clinical services, 11.8 percent health education, 11.8 percent preventive dentistry, and 8.7 percent community activities. From the data collected, it is apparent that the majority of North American dental schools are providing a variety of extramural experiences for their dental students. It was found that student involvement in extramural programming increases gradually from the freshman to the senior year.
A professionally managed telephone survey was undertaken to assess community-perceived need and demand for orthodontic treatment, and to determine the proportion of the community with a history of having some form of orthodontic treatment. The sample included 505 respondents, aged eighteen and over, from metropolitan and non-metropolitan households across the state of Victoria in Australia. The sample distribution had a ninety-five per cent confidence limit with a five per cent margin of error, and closely matched the known population distributions for age, sex and geographical location. From the survey it can be concluded that apparently forty-four per cent of Victorian families include someone who has already received some form of orthodontic treatment. Twenty-five per cent of the survey respondents perceived some need for the treatment of a family member; only fifteen per cent of respondents, however, reported that someone in their family actually wanted treatment. This survey has established baseline values for community perceived need and demand for orthodontic treatment. Use of these values should assist in future resource management within both the public and private sectors.
Salient, task-irrelevant stimuli that consistently appear with the same defining feature (e.g., a specific color) can be actively downweighted by the visual system. This attentional suppression mechanism has been shown to benefit visual search: Search targets are more efficiently located in displays with a salient color singleton distractor than in displays without a distractor. The singleton presence benefit has been commonly attributed to reduced allocation of attention to the location of the distractor. We question here whether suppression merely excludes locations for attentional selection, or whether the suppressive mechanism fundamentally alters the representation of other elements in the scene. To examine this question, we assessed the effects of suppression on nearby elements by perceptually grouping sets of elements together in the search array. On different trials, the search target either appeared in the same perceptual group as a to-be-suppressed color singleton distractor, at an equidistant location but in a different group, or at a more distant location in a different group. Experiment 1 showed that selection of the target was enhanced when it was grouped with a suppressed distractor. Experiment 2 varied the locations grouped together from trial to trial, and also demonstrated a same-group benefit. To test whether participants strategically prioritized the group containing the salient distractor (because it had fewer potential target elements), Experiment 3 changed the number of elements in each group. Target selection was enhanced when grouped with the distractor even when the distractor-containing group had more items to search. Consistent with the effects of grouping, a benefit of closer target-distractor distance was also observed in the experiments. Together the results reveal the novel finding that attentional suppression facilitates selection of stimuli near the distractor, implying that distractor downweighting may be achieved by biasing the competition for representation in favor of surrounding locations.
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