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Biomedical subjects

F Schieber

Publications and source records attributed to F Schieber.

8 recordsLinked to original sources
PubMed1992

Vision, aging, and driving: the problems of older drivers.

Although there are well-recognized declines in visual functioning with age, their contribution to the problems of older persons on tasks in the natural environment, including driving, are largely unknown. Adults ranging in age from 22-92 years were surveyed in regard to their visual difficulties when driving and performing everyday tasks. The visual problems of drivers increased with age along five different visual dimensions: unexpected vehicles, vehicle speed, dim displays, windshield problems, and sign reading. Several of the age-related visual problems that were reported appear to be related to the types of automobile accidents more common among older drivers. The study also replicated the findings from an earlier investigation of non-driving tasks that showed visual declines with age on five dimensions: visual processing speed, light sensitivity, dynamic vision, near vision and visual search. These findings indicate promising areas of research regarding the effects of visual aging on tasks in the natural environment.

Adult↗
PubMed1991

Visual requirements for safety and mobility of older drivers.

Efforts to assess visual deterioration with increasing age, coupled with new mechanisms proposed to limit the exposure of visually impaired drivers to driving risks, have emerged in response to the increase in older drivers. Visual functions discussed in this context include static acuity (photopic, mesopic, and in the presence of glare), dynamic visual acuity, visual field, contrast sensitivity, and motion perception. Exposure control mechanisms discussed include alternative periodic vision testing strategies, visual training, and environmental and vehicular modifications to accommodate the older driver. Finally, relevant research needs are addressed.

Aging↗
PubMed1983

Age, the eye, and the visual channels: contrast sensitivity and response speed.

Age differences in spatial vision were examined by establishing contrast sensitivity functions for young and old adults. In addition, differences in the speed of operation of the different visual channels and their contribution to age differences in reaction time were assessed in a comparison of response speed to sinusoidal gratings of varied spatial frequency. An age-related loss in contrast sensitivity was observed primarily for stimuli of intermediate and high spatial frequency, an effect apparently due mostly to age-related optical differences. Reaction time varied markedly as a function of spatial frequency for the older participants, an outcome only partly attributable to age differences in target visibility. These data indicate a slowing in the speed of operations of individual visual channels and/or a change in the relationship between visual channel classes. These findings also raise a question in regard to the meaning and comparability of any studies that have used measures of response latency to the figural aspects of stimuli.

Adolescent↗
PubMed1981

What are the age differences in visual sensory memory?

The present investigation examined age differences in visual persistence using a direct measurement technique of Haber and Standing (1969). Young and old adult subjects were compared as to the apparent continuity of a circle when it was alternated cyclically with a second blank interstimulus field of variable duration. Contrary to a previous study, old subjects demonstrated significantly greater levels of persistence. Contrast relationship of the target stimulus and its background did not interact with age. Although the data were consistent with a hypothesis of increased persistence of stimuli in the senescent nervous system, alternatively they suggest problems in the direct measurement technique.

Adolescent↗
PubMedDate not supplied

Age and the discrimination of visual successiveness.

Using a visual successiveness paradigm, young and old adult subjects were compared as to their ability to judge the order of offset of briefly-presented visual stimuli. Consistent with the stimulus-persistence hypothesis and a possible age-related increase in the period of a central perceptual scanning mechanism, old subjects required significantly greater levels of stimulus asynchrony to discriminate order of offset. More generally, these data indicate an age-related loss in the mechanisms which process visual "transients".

Adolescent↗
PubMedDate not supplied

High-priority research and development needs for maintaining the safety and mobility of older drivers.

The increase in the number of older drivers has resulted, in the last two decades, in a series of conferences and workshops that have outlined the magnitude of the "older driver problem." More than 150 research and development recommendations generated by these conferences were rated by a task force of the Transportation Research Board in terms of their relative importance. On the basis of this rating, six major categories of high-priority research and development needs were identified: highway design, vehicle design, licensing and rehabilitation, vision and visual assessment, biomedical issues, and general issues. The current status of research in each of the categories is reviewed, and the most important avenues for future inquiry are outlined.

Aged↗
PubMedDate not supplied

Age differences in the temporal continuity of gratings as a function of their spatial frequency.

This study compared young and elderly observers on the continuity of sinusoidal grating-pairs as a function of interstimulus interval (ISI) and spatial frequency (.5, 1.0, 2.0, 4.0, 8.0, and 12.0 c/deg). Consistent with prior research, the maximum ISI over which pattern continuity was maintained increased with spatial frequency. In addition, among older observers, grating continuity occurred at significantly longer ISI's at the two lowest spatial frequencies; no age difference was observed at the higher spatial frequencies. These results could not be attributed to an age difference in retinal illumination associated with pupillary miosis. However, they do indicate an age-related decline in detecting visual offset and are consistent with the hypothesis of a decline in the effectiveness of the transient visual channels.

Adolescent↗