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Biomedical subjects

D W Kline

Publications and source records attributed to D W Kline.

15 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↗
PubMed1990

Self-reported visual problems of older drivers.

We conducted a survey in order to gain insights into the reasons older persons decide to give up driving. Our survey focused on vision. We probed the relationship between visual deficiencies and driving status by asking older people about the problems they encountered while performing routine visual tasks. The results showed that older persons who had recently given up driving reported more visual problems than did their driving counterparts. These problems related to difficulties in dynamic vision, visual processing speed, visual search, light sensitivity, and near vision. The results suggested that older persons are sensitive to their own visual deficits and that this awareness influences decisions about driving.

Activities of Daily Living↗
PubMed1990

Visibility distance of highway signs among young, middle-aged, and older observers: icons are better than text.

The visibility distances for young, middle-aged, and elderly observers of text and icon versions of four different highway signs were compared under day and dusk lighting conditions. No age differences were observed. Icon signs, however, were visible at much greater distances than were text signs for all three age groups, a difference that was more pronounced under dusk conditions. There were no age differences in the comprehension of icon signs, but there was considerable variability from one icon sign to another in the degree to which they were comprehended. Acuity was found to be a better predictor of the visibility distance of text signs in both day and dusk conditions than it was of icon signs. To the degree that they are comprehended, icon signs appear to offer drivers of all ages almost twice as much time in which to respond to them.

Adult↗
PubMed1988

Effects of noise type and retinal eccentricity on age differences in identification and localization.

Twenty young (M = 24 yrs), and 20 older adults (M = 62 yrs) identified and localized two target letters presented nonfoveally in each of three noise conditions. Targets were presented in isolation, embedded in featurally similar distractors, or embedded in distractors that were featurally similar to the alternate response. Older adults were generally slower to identify targets, particularly in multi-element arrays. Age differences favoring the elderly were found in target-similar identification accuracy, but the young identified targets more accurately in alternate-similar noise. Localization errors were greater among the elderly, who exhibited a bias to localize targets to central array positions. Age differences in noise effects are explained as resulting from ontogenic change in the duration of temporal integration required to encode arrays to the level of a primary detection response (Estes, 1982). The model's predictions were given small-scale validation when visibility was decreased in young adults who then produced performance profiles similar to the elderly.

Adult↗
PubMed1987

Age differences in target identification as a function of retinal location and noise level: examination of the useful field of view.

Foveal and peripheral target detection were compared in young adults (M age = 22 years) and older adults (M age = 66 years) who were optically corrected for the viewing distance. In a two-alternative, forced-choice task, target letters were presented at 0 degree to 10.5 degrees from fixation. Targets were presented alone, flanked on each side by one noise element (i.e., nontarget letter), or embedded in a horizontal row of 19 noise elements. An Age X Noise Level X Location interaction was obtained, wherein age differences were largest for peripheral targets presented in noise. Slope analyses of latency data showed that the performance of young adults in the high-noise condition was most similar to that of older adults in the low-noise condition. At the functional level, results indicated that aging is associated with a restricted useful field of view. In addition, the data suggest that age differences in search can be described by a model in which older adults take smaller perceptual samples from the visual scene and scan these samples more slowly than do the young adults.

Adult↗
PubMed1987

Ageing and the spatiotemporal discrimination performance of the visual system.

Visual ageing is generally associated with a decline in spatial vision for stationary stimuli, especially those which are of high spatial frequency. Some, but probably not all of this loss can be attributed to apparently normal age-related changes in the ocular media that attenuate and scatter incident light. The loss in the temporal resolving capacity of the senescent visual system is even more prominent and appears to be due almost completely to neural mechanisms, including alterations in the functioning of both the 'transient' and 'sustained' types of visual channel. The losses with age in both spatial and temporal vision are highly consistent with the type and degree of visual problems elderly persons report that they experience in carrying out daily tasks. Further research will be needed to determine the mechanisms which underlie these changes as well as to determine the degree to which they can be remedied.

Activities of Daily Living↗
PubMed1978

Stimulus persistence in CFF: overarousal or underactivation?

The physiological basis of hypothesized adult age increases in the persistence of stimuli was studied in 16 young (X age 19.1 years) and 16 old (X age 70.1 years) male and female subjects. Changes in CFF threshold and skin conductance were measured as a function of loud white noise activation and artificial pupil. CFF was significantly lower in the old group and with artificial pupil in both age groups. Significant effects were also found for activation x sex and activation x age x sex. Skin conductance change was significant for activation, activation x sex, artificial pupil x age, artificial pupil x order and artificial pupil x order x activation. The results were interpreted as supporting an overarousal basis of an age increase in stimulus persistence.

Adolescent↗
PubMed1978

Examination of stimulus persistence as the basis for superior visual identification performance among older adults.

Visual identification performance of sequentially presented corresponding word-halves was studied in 12 young (mean 18.9 years, range 18-21) and 12 old (mean 68.0 years, range 59-78) male and female subjects. Corresponding word-halves were composed of straight horizontal and vertical line segments and when superimposed tachistoscopically formed clear, fully closed 3-letter words. Stimulus duration and interstimulus interval (ISI) were systematically varied. Correct word recognition was found to be an inverse function of ISI and stimulus duration for both young and old subjects. An interaction was found between age, sex, and stimulus duration. Recognition scores were significantly higher among older subjects, an effect which was particularly prominent at greater ISIs. The data offer strong support for the stimulus-persistence model as applied to age differences in the sequential integration of form.

Adolescent↗
PubMed1977

Persistence of complementary afterimages as a function of adult age and exposure duration.

The persistence of complementary afterimages was studied in 36 young (X age 18.8 years) and old (X age 62.1 years) male and female subjects. Afterimage persistence was found to be a direct function of exposure duration and to be greater for the older subjects as compared with the younger ones. The interactions between age and duration and between presentation order and duration were also significant. The data extend support for the "stimulus persistence" model to age differences in retinal function.

Adolescent↗
PubMed1977

Differences in unconspicuous word identification as a function of age and reversible-figure training.

Inconspicuous word identification was studied in 48 young (X age 19.3 years), middle-aged (X age 44.5 years) and old (X age 69.5 years) male and female subjects. Although this task appeared to be an easy one for the young subjects, it was strikingly difficult for the middle-aged and elderly subjects. Reversible-figure training apparently led to a small but significant overall improvement in inconspicuous word identification but did not at all diminish the age differences in such performance. The interactions of sex by reversible-figure training and age by first set-second set of words were also significant. Further research will be needed to fully examine the remediability of age-related perceptual skill deficits.

Adult↗
PubMed1976

Differences in the sequential integration of form as a function of age and interstimulus interval.

The sequential integration of visual stimuli was studied in 12 young (18-28 years) and 12 old (51-62 years) men and women. Stimuli were constructed as corresponding word halves and inter-stimulus intervals (ISI's) of varied duration (0-150 msec.) were introduced between the presentation of the two halves. Correct word identification was found to be an inverse function of ISI for both young and old subjects. The number of stimuli correctly identified was significantly lower for the older subjects at all levels of ISI. None of the interactions of age, sex, and ISI was significant. The data appear to question the "stimulus persistence" model as applied to age differences in the temporal organization of form.

Adult↗
PubMed1975

Age differences in backward dichoptic masking.

An investigation of age differences in backward dichoptic visual noise masking was carried out with young, middle-aged and old subjects. Older subjects were found to be significantly more susceptible to the backward masking effect over longer delays between the target and masking stimuli. These results indicate a decrease with age in the rate at which stimuli can be cleared through the central mechanisms concerned with perceptual processing. These data appear to support the "stimulus persistence" and "arousal" models of aging.

Adult↗
PubMed1975

Age differences in backward monoptic visual noise masking.

An investigation of age differences in backward monoptic visual noise masking was carried out with young and old adult subjects. It was found that the older subjects were susceptible to the backward masking effect over significantly longer delays between the target and masking stimulus. The masking effect seems to be, at least in part, attributable to age changes in the central mechanisms concerned with perceptual processing which limit the rate at which stimuli can be "cleared" through the nervous system. Backward masking studies of different types seem to hold considerable promise for assessment of the peripheral and central components of age change in visual perceptual processing.

Adult↗
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↗