Search

To evaluate the ability to predict on-road driving in cognitively impaired older drivers.Cross-sectional observational study.Laboratory tests and on-road assessment.Drivers with cognitive impairment (Mini-Mental State Examination score26, N = 43, mean age 74).The Roadwise Review, a hazard perception test (HPT), several vision tests, and a standardized 18-km driving assessment.The best prediction of passing or failing the on-road test was a combination of the HPT, leg strength, visual acuity, visual search and working memory, and number of medications taken (Nagelkerke coefficient of determination = 0.40). The sensitivity of the model was 71%, and the specificity was 75%.Further research is required to determine how these tests may be used or combined with other data (e.g., medical history) to assess fitness to drive of cognitively impaired older drivers.

Background/Study Context: We are often required to carry out complex tasks in changing, context-dependent ways. This task switching requires the rapid realignment of attention to task constraints and may be age sensitive. Methods: Three experiments, two in which eye movements were recorded, were conducted to assess age-related differences in task switching and inhibitory control. Observers carried out a Same-Different task and Go-No Go task in single and mixed blocks of trials. Results: Other than Experiment 1, although switch costs were observed, they were not larger for older adults compared to younger adults. Furthermore, eye movement and false alarm data demonstrated little evidence of age-related decline in inhibitory and oculomotor control. Conclusions: A major implication is that, at least when two tasks involve different stimuli and unique responses, older adults are no more likely than younger adults to show task-switching costs or inhibition deficit.

The Roadwise Review has been reported to provide an effective means of self-assessing and predicting driving difficulties in older adults. We administered it to 73 community-dwelling older drivers (M = 73 years) and also gathered data on self-reported driving difficulties, 2-year retrospective collisions, and moving violations. The acuity tests and Useful Field of View exhibited substantial ceiling effects that limit predictive utility, and there was a high failure rate on the head and neck flexibility test. Additionally, the Roadwise Review did not predict self-reported driving problems or collision risk. Thus, in current form, it does not appear to be a useful tool for assessing older drivers. Future research efforts should assess predictive validity in a more heterogeneous sample of older adults and with a broader range of outcomes, including on-road driving performance. Copyright 2010, Oxford University Press.

One reason that older drivers may have elevated crash risk is because they anticipate hazardous situations less well than middle-aged drivers. Hazard perception ability has been found to be amenable to training in young drivers. This article reports an experiment in which video-based hazard perception training was given to drivers who were between the ages of 65 and 94 years. Trained participants were significantly faster at anticipating traffic hazards compared with an untrained control group, and this benefit was present even after the authors controlled for pretraining ability. If future research shows these effects to be robust, the implications for driver training and safety are significant.

INTRODUCTION: The current study builds on previous versions of the Driver Behaviour Questionnaire (DBQ) by incorporating a larger sample of driving behaviors targeting inattention, distraction, aggressive driving, and health related to aging. The goals of this study were to determine if the resulting factor structure was consistent with a more contemporary view of unsafe driving behaviors, and to determine whether scores on the factors could predict self-reported collisions and police citations. METHODS: The instrument was given to a sample of 3295 drivers ranging in age from 19 to 80+ years old. It was divided in two sections, the first to provide demographic information and driving history data and the second containing 105 driver behavior questions. RESULTS: An exploratory factor analysis resulted in a 65-item scale organized in four factors. The factors were labeled tentatively as Inattention Errors, Age-Related Problems, Distraction and Hurry, and Aggressive Violations. Regression analyses showed that the factors were predictors of self-reported, at-fault collisions and police citations. PRACTICAL IMPLICATIONS: The factor scores found in this research are consistent with a useful theoretical framework for understanding unsafe driver actions, and demonstrate some potential to identify several individual difference variables that predict self-reported collisions and citations. Keywords: Driver distraction; Language: en

Potential age-related differences in the memory processes that underlie visual search are examined in the present study. Using a dynamic, gaze-contingent search paradigm developed to assess memory for previously examined distractors, older adults demonstrated no memory deficit. Surprisingly, older adults made fewer refixations compared to their younger counterparts, indicating better memory for previously inspected objects. This improved memory was not the result of a speed-accuracy trade-off or larger Inhibition-of-Return effects for older than for younger adults. Additional analyses suggested that older adults may derive their benefit from finer spatial encoding of search items. These findings suggest that some of the memory processes that support visual search are relatively age invariant.

The purpose of this study was to examine whether executive dysfunction differentially impacts list-learning and story recall tasks in a sample of older adults referred for suspected cognitive impairment. Older adults (N = 61) with mild cognitive impairment (MCI) or probable mild dementia, and those who did not meet criteria for diagnosis of dementia, were assessed using measures of executive function and verbal memory. Two groups were established based on performance on measures of executive function: (a) the No Executive Dysfunction group (NoED; n = 33) consisted of persons without impairment on any obtained measures of executive function; and (b) the Executive Dysfunction group (ED; n = 28) contained persons with impairment on at least one of the measures of executive function. The two groups were compared on performance on two measures of verbal memory, the California Verbal Learning Test-II (CVLT-II) and the Logical Memory (LM) subtest from the Wechsler Memory Scale-Revised (WMS-R). The NoED group performed significantly better than the ED group on the total learning and short delay free recall trials of the CVLT-II. However, there were no significant differences between the groups on the other indices of the CVLT-II (i.e., long delay free recall, recognition, recall repetitions, recall intrusions, or recognition false-positives) or on the immediate and delayed recall trials of the LM measure. These results support previous research demonstrating the impact of executive dysfunction on the acquisition of and short-delay retrieval of verbal information in older adults with suspected cognitive impairment.

The effects of divided attention were examined in younger adults (M = 23 years) and older adults (M = 64 years) who searched for traffic signs in digitized images of traffic scenes. Sign search was executed under single-task and dual-task conditions in scenes containing either small or large amounts of visual clutter. For both age groups, clutter and the secondary task had additive effects on search accuracy, speed, and oculomotor involvement. Compared with the younger adults, older adults were less accurate, especially with high-clutter scenes, were slower to decide that a target sign was not present, and exhibited a marginally greater divided-attention effect on reaction times. They exhibited longer fixations in the divided-attention condition, in which they also showed a disproportionate reduction in recognition memory for the content of the secondary task. Actual or potential applications of this research include methods for evaluating the distraction of conversations and safety implications of conversation on visual search behavior.

Younger and older participants were trained in a triple conjunction visual search task to examine age differences in the development of proficient performance. For the first 8 days, participants searched for a target defined by its contrast polarity, shape, and orientation. On Days 9 through 16, the target identity was switched to one defined by opposing feature values. On Day 17, the target was returned to the original feature values. Results indicated that, after training, younger adults reduced their display size effects more than elderly adults. Disruption occurred after the first but not after the second transfer. However, each time the target was switched, there were no age differences in disruption. Eye movement data suggest that older adults use a similar feature selection strategy as younger adults but may be more susceptible to distraction. The results are discussed in terms of current models of attention and search.

Performance on complex, cognitive tasks often is sensitive to low-level sensory and perceptual factors. These relations are particularly important for cognitive aging researchers because aging is associated with a variety of changes in sensory and perceptual function. In the article that follows, I first selectively outline some relations between task performance and sensory function. Next, I summarize age-related changes in visual function and the implications of these changes for task performance, using the digit-symbol subtest of the WAIS as an example. I offer some reasons why age-related sensory decline may not be important to all cognitive tasks. Finally, I provide several recommendations for cognitive gerontologists who want to minimize the risk that the age differences they observe are sensory in nature. The past decade of cognitive aging research has produced a small, but provocative and influential number of studies that suggest a rather strong correlation between age-related differences in sensory measures like visual acuity and cognitive measures of attention, memory, and intelligence. Understandably, these data are generating an uncertain and mixed reaction within the gerontological community. On the one hand, the possibility of a common or general cause of cognitive aging has parsimonious and clear intellectual appeal. On the other hand, such findings complicate the work of researchers who wish to attribute age differences in task performance to cognitive mechanisms. To motivate the discussion by example, Lindenberger and Baltes (1994) assessed corrected visual acuity and audiometric thresholds, along with several measures of cognitive function (e.g., reasoning) in over 150 people older than 70 years of age. The interrelationships among some of the variables are shown in Figure 1. Aging is strongly correlated with both visual and auditory function, which in turn have a substantial impact on cognition. Such a pattern is consistent with the view that age changes in cognition reflect a common factor that is also indexed by sensory function. However, the data are also compatible with the assertion that age differences in cognition are caused by sensory deficits that make it more difficult for the elderly to process the test materials. In fact, this is the position implicit in the model shown in Figure 1, because age impacts cognition only indirectly through its influence on sensory function. The substantial relations between sensory and cognitive function are not, as might be hypothesized, a result of selecting only an older sample in which undetected disease causes correlated interindividual differences in sensory thresholds and cognitive behaviour. Moderate to large correlations between age, sensation, and cognition have been found in life-span samples (Baltes & Lindenberger, 1997; Salthouse, Hancock, Meinz, & Hambrick, 1996) and in longitudinal designs (Schaie, Maitland, & Willis, 2000). Neither do the correlations result spuriously from age-related changes in response criterion (Burton, Owsley, & Sloane, 1993; Higgins, Jaffe, Caruso, & de Monasterio, 1988). Stevens, Cruz, Marks, and Lakatos (1998) found correlations between forced-choice measures of sensory function and performance on the Boston Picture Naming Test and Logical Memory subtest of the Wechsler Memory Scale ranged from .35 to .78 in small, select groups of younger and older adults. The magnitude of the relationship appears to vary with sensory modality, but not always in ways that allow for easy causal models. For example, Glass (2000) reported that visual contrast sensitivity accounted for more age-related variance in spatial tasks than in verbal tasks. On the other hand, Stevens et al. found that it was touch and taste thresholds that had the highest correlations with the Logical Memory test. The sensory-cognitive link appears to be quite robust, crossing task domains as diverse as problem-solving and fluency (Lindenberger & Baltes, 1994), concept identification (Salthouse et al. …

Introduction : This study evaluated the ability to predict the on-road driving of older drivers using a battery of laboratory-based instruments. Methods : The Roadwise Review, a brief Hazard Perception Test and several tests of vision were given to 65 cognitively healthy, licensed older drivers ( M = 74 years, SD = 9 years). They also participated in a standardized driving assessment of approximately 18 km, along a mixed residential and commercial route. Results : Raw scores on the Roadwise Review did not predict accumulated points, or automatic disqualifications, but could predict who would pass or fail the on-road evaluation. The number of serious problems (excluding head and neck flexibility) that were identified by the Roadwise Review was a significant predictor of automatic disqualifications, and a significant predictor of passing or failing the on-road assessment. The Hazard Perception Test approached significance when predicting accumulated points and was a significant predictor of automatic disqualifications, as well as pass/fail outcomes. Conclusions : The best model for predicting passing or failing the on-road assessment included the Hazard Perception Test, color vision, and, a measure of walking speed from the Roadwise Review, which yielded a sensitivity of 82% and a specificity of 69% (AROC = .80). Future work will need to determine how these tests can be used with other information (e.g., medical history) to yield better diagnoses of fitness to drive, particularly among those who are medically at risk.

Three experiments investigated the generalisation of contextual cuing and whether the effect is incidental or intentional in nature. Experiment I assessed contextual cuing across variations in display contrast, homogeneity, and spatial separation. Cuing effects were found with all display types and reaction-time disruption was manifested for repeated displays when consistent configurations had their target locations altered. Recognition memory for repeated displays was at chance levels. Experiment 2 showed that contextual cuing was insensitive to instructions to search for and remember repeated displays. Experiment 2A found that there were no age differences in contextual cuing or effects of intentional instructions, and no memory for repeated displays. Future research questions concern the generalisation of contextual cuing to a wider variety of display conditions and naturalistic tasks.Keywords: contextual cuing, incidental versus intentional processing, cognitive agingVisual search, the process of detecting, localizing, and identifying task-relevant objects embedded within visual environments, is influenced by the physical properties of target items (e.g., Scialfa & Joffe, 1997; Wolfe, 1992), as well as the global configuration of elements within a display (Chun & Jiang, 1998; Chun & Phelps, 1999). Chun and Jiang reported that the spatial layout of a display could be learned unconsciously and facilitated performance when the locations of the target and distractors remained stable over repetitions. The magnitude of this effect, termed contextual culnfi, grew with experience.In the experiments reported in this article, we examined contextual cuing with four objectives. The first was to determine if the effect generalised across differences in low-level stimulus properties, such as contrast and object size, that vary in their demands for focused attention. Second, we examined the disruption in performance following changes to previously consistent display configurations. The third objective was to discern if instructions to intentionally monitor displays for spatial consistency had no effect on performance, as would be expected if contextual cuing is an incidental process. Finally, because older observers are expected to perform as well as their younger counterparts in incidental tasks, we compared younger and older adults' contextual cuing effects.In the first of several contextual cuing studies, Chun and Jiang (1998) had participants search displays that were composed of one target embedded among 11 distractor items. The target (the letter "T") was similar in size and form to the surrounding distractors (the letter ''L''). Trials were divided into blocks, each containing 24 visual search trials. Twelve of these trials were repeated in each block, whereas the remainder were generated randomly and were not repeated. Reaction times decreased as a function of task experience, but, of greater interest, reaction times (RTs) for repeated displays were faster than those for novel displays and the magnitude of this difference increased as participants progressed through the experiment.To determine whether this contextual cuing was caused by regular spatial relationships between the target and the distractors, the location of the target item was then varied within repeated displays. The contextual cuing effect was eradicated, suggesting consistency in relative location as a mechanism mediating faster responses in repeated displays. Subsequent studies (Chun & Phelps, 1999; Olson, Chun, & Allison, 2001) found the contextual cuing effect to be robust and reliable, its magnitude varying between 40 and 150 ms.Further research has established some of the factors influencing contextual cuing. It appears to operate in the absence of eye movements (van Asselen & Castelo-Branco, 2009) and. when arrays of simple objects (e.g., letters and numbers) are used, depends more heavily on local, rather than global, consistency of elements (Hoffmann & Sebald. …

Two experiments used the progressive demasking (PD) task to examine age differences in the ability to inhibit higher frequency competitors during the process of identifying a visually degraded word. In Experiment 1, older adults exhibited a larger inhibitory neighborhood frequency effect (i.e., slower identification of words with many higher frequency competitors) than younger adults, but additional analyses indicated that this difference could be explained by general slowing rather than a deficit in inhibitory abilities. In Experiment 2, a primed version of the PD task was used to promote hypothesis testing by semantically priming the target word (e.g., cry-weep) or a higher frequency competitor of the target (e.g, day-weep) prior to the onset of the demasking sequence. Although older adults were more likely to make identification errors consistent with an inhibitory deficit (e.g., identifying weep as week), these errors were infrequent overall and there was no corresponding evidence of a larger interference effect in the older adults' identification latencies. Taken together, performance in these two tasks provides little evidence of reduced inhibitory functioning in older adults. The implications for the inhibitory deficit hypothesis of cognitive aging and directions for future are discussed.

In two experiments, younger and older observers carried out feature searches for targets defined by their luminance contrast and orientation. Additionally, they received consistent-mapping (CM) training in luminance contrast by orientation conjunction search, followed by a brief exposure to conjunction search under reversal conditions. In Experiment 1, display size effects on reaction time suggested that both younger and older observers were conducting a parallel search in all conditions and showed equivalent disruption at reversal. Experiment 2 was a substantive replication of the first using more difficult conjunction search displays. In addition to latency, we measured the number, duration, and feature-based selectivity of fixations made during conjunction search. Display size effects were larger than in Experiment 2 and were of equivalent magnitude in younger and older people. There were no age differences in improvement in conjunction search and minimal age differences in disruption following reversal. Both age groups demonstrated early in training that they could select items possessing target features (i.e., the color white), and both age groups demonstrated that they could not completely reverse this selectivity when these features no longer defined the target. These experiments have several implications for models of visual attention and age differences therein.

Younger and older adults were asked to saccade to an orientation-defined target that was presented alone, with a more central distractor, or with a more peripheral distractor. Both age groups exhibited saccadic averaging that was more pronounced in the central distractor condition, wherein older adults had the larger effect. These results are relevant to questions of oculomotor control and also have implications for the study of age differences in other visually guided behaviors.

INTRODUCTION: The Driver Behaviour Questionnaire (DBQ), originally developed in Britain by Reason et al. [Reason, J., Manstead, A., Stradling, S., Baxter, J., & Campbell, K. (1990). Errors and violations on the road: A real distinction? Ergonomics, 33, 1315-1332] is one of the most widely used instruments for measuring driver behaviors linked to collision risk. METHOD: The goals of the study were to adapt the DBQ for a North American driving population, assess the component structure of the items, and to determine whether scores on the DBQ could predict self-reported traffic collisions. RESULTS: Of the original Reason et al. items, our data indicate a two-component solution involving errors and violations. Evidence for a Lapses component was not found. The 20 items most closely resembling those of Parker et al. [Parker, D., Reason, J. T., Manstead, A. S. R., & Stradling, S. G. (1995). Driving errors, driving violations and accident involvement. Ergonomics, 38, 1036-1048] yielded a solution with 3 orthogonal components that reflect errors, lapses, and violations. Although violations and Lapses were positively and significantly correlated with self-reported collision involvement, the classification accuracy of the resulting models was quite poor. PRACTICAL APPLICATIONS: A North American DBQ has the same component structure as reported previously, but has limited ability to predict self-reported collisions. Keywords: Driver distraction; Language: en

Objectives. The ability to perceive high spatial frequencies (i.e., fine detail) is impaired when contours are placed near the detail to be resolved (Bouma, H. [1970]. Interaction effects in parafoveal letter recognition. Nature, 226, 177-178. doi:10.1038/226177a0; Flom, M. C., Weymouth, F. W., & Kahneman, D. [1963]. Visual resolution and contour interaction. Journal of the Optical Society of America A, 53, 1026-1032. doi:10.1364/JOSA.53.001026.). This visual crowding is more pronounced outside of central vision and may be more pronounced in older adults. Thus, the motivation for the present study. Method. Younger (M = 20.95 years) and older adults (M = 70.32 years) detected gap orientation in a Landolt C presented at 3° or 6° either alone or flanked by bars of the same spatial scale. Results. Both age groups demonstrated a visual crowding effect, in that acuity deteriorated in the flanking condition, an effect that grew with eccentricity. Older adults exhibited a larger crowding effect, particularly at 6°. Younger adults tested at reduced illumination did not show the crowding effect of older adults. Thus, age differences do not appear to result from reduced retinal illumination. When the crowding effect was operationalized as the ratio of crowded to uncrowded acuity, age differences were eliminated at both 3° and 6°. Discussion. These data have implications for understanding age differences in functional vision, including reading and visual search. Language: en

Age deficits in visual search often are attributed to difficulties in comparing display items to target representations. In the presence-absence search paradigm, however, these comparisons are frequently confounded with age differences in the latency and velocity of saccadic eye movements, reductions in the useful field of view (FOV), and retention of information concerning previously searched locations. To circumvent these shortcomings, 20 young and 20 older adults were compared in the speed of their same-different judgments of two perifoveal stimuli. The two stimuli were either identical or varied along one or more of the dimensions of size, shape, and color. In both age groups, RT for correct "different" judgments increased with stimulus similarity, an effect which was more pronounced in the elderly subjects. Results suggest that age differences in free search are due, in part, to an age-related decline in the speed of evaluating object congruence.

Contrast thresholds for sinusoidal gratings of 1.5-18 cpd were measured in young (M = 24 years) and older adults (M = 69 years). Thresholds were determined for stationary gratings, and for gratings that traveled along a circular path at 5, 10, and 15 deg/sec. For static gratings, age differences in thresholds were greater for intermediate and higher spatial frequencies. Grating motion increased thresholds for all observers, but older adults exhibited threshold increases at lower target velocities than the young. Age differences in velocity effects were generally greater at intermediate and higher spatial frequencies. Results are discussed in relation to age changes in temporal resolution and smooth pursuit gain.

To assess the reliability of the Vistech Contrast Test System (VCTS), contrast sensitivity functions (CSF's) were estimated using all forms of the VCTS in 92 subjects aged 20 to 73 years, who were refracted for the test distance. Over a 3-month period, nine estimates at each spatial frequency and an equivalent number of acuity measures were obtained. The contrast sensitivity of older adults was lower than that of the younger adults, particularly at higher spatial frequencies. Practice effects which varied as a function of spatial frequency were also observed. Reliabilities for single-form estimates of contrast sensitivity (CS) were frequency-dependent, and ranged from 0.41 to 0.65. Three-form average estimates of CS yielded reliabilities ranging from 0.62 to 0.77. Consistent with the assertion that low VCTS reliabilities are due, in part, to measurement error, the reliabilities for acuity were uniformly higher than for the VCTS. Results are discussed in relation to clinical use of the VCTS across the life-span.

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.

Latencies (RT) and eye movement measures were used to examine the effects of age and contrast on the distractor-ratio effect (DRE) in visual search. Younger and older adults performed a contrast x orientation conjunction search task where the ratios of white to black distractors and luminance contrast levels were varied. The distractor-ratio manipulation had similar effects for older and younger adults on both RT and the number of fixations required to find the target. Both measures were largely independent of distractor ratio on target-present trials, while both RTs and the fixation number increased with the number of items sharing the target's contrast polarity on target-absent trials. A more detailed analysis of eye movements suggested that younger adults were a bit more adept at attending to the smaller set of distractors, which presumably facilitated both overt and covert search. Generalized slowing can account for the age differences in RT, but the fixation number data speak to another mechanism, perhaps increased cautiousness on the part of the elderly when signal strength is low.

The influence of age, subject matter knowledge, working memory, reading abilities, spatial abilities, and processing speed on Web navigation was assessed in a sample of 41 participants between the ages of 19 and 83 years. Each participant navigated a stand-alone tourism Web site to find answers to 12 questions. Performance was measured using time per trial, number of pages per trial, and number of revisited pages per trial. Age did not influence the number of total pages or repeat pages visited, which were predicted by domain knowledge, working memory, and processing speed. Age was associated with slower times per trial, and the effect remained significant after controlling for working memory, processing speed, and spatial abilities. Only with the addition of subject matter knowledge and World Wide Web experience was the age effect eliminated. Actual or potential applications of this research include redesigning Web sites to minimize memory demands and enhance visual segmentation. The data also suggest that age differences in Web navigation can be offset partially by taking advantage of older adults' prior experiences in the domain.

Ten younger and ten older adults were provided with 16 sessions of conjunction search under consistent mapping, where target and distractors remain constant in identity. The target and one distractor were reversed after every fourth session. After the first four training sessions, on target-present trials, display size slopes were near zero for both age groups. However, on target-absent trials, older adults continued to show significantly larger display size effects than younger adults. There were no systematic age differences in either the probability of fixating objects that possess the target's features or in the amount of disruption at any reversal. Thus, although older adults exhibited more conservative criteria in visual search, they developed proficient and flexible search skill to the same degree as their younger counterparts. These data have implications for models of visual attention, skill acquisition, and cognitive aging.

Latency and eye movement measures were used to examine the effects of aging, clutter, and luminance on visual search for traffic signs embedded in digitized images of driving scenes. Initially 14 older and 14 younger observers classified daytime and nighttime traffic scenes as containing low or high amounts of clutter. Next, an independent sample of 14 younger and 14 older participants searched for traffic signs contained within these scenes. Errors were more common among the elderly. Search efficiency declined with increased clutter and with aging. However, relative to the young, older adults did not suffer disproportionately as a result of increased clutter. The methods developed might be profitably employed to assess sign conspicuity and sign acquisition during driving.

Younger and older adults were asked to find a single target in both feature- and conjunction- search conditions. Display size varied between 2 and 8 items, and target-distractor similarity ranged from relatively low to high levels. The accuracy data indicated that older adults had particular difficulty finding targets in high-similarity conjunction-search displays containing a large number of distractors. The reaction time (RT) analyses found larger age deficits in many of these same conditions. For both groups, predictions of conjunction search based on Treisman and Sato's additive model (Journal of Experimental Psychology: Human Perception and Performance, 1990: 16, 459-478) departed significantly from actual performance. The RT data of older observers were, in large part, predicted as a simple linear function of the young adults' data. These results are discussed with respect to age differences in selective attention, generalized slowing, and an age-related loss in search efficiency.

Older and younger observers searched for two targets embedded in response-compatible or -incompatible distractors. Display duration was varied across trial blocks from 26 to 1,664 ms. For both age groups, response-incompatible displays led to relatively poorer accuracy, particularly at brief durations. Age differences in accuracy were larger for response-incompatible displays and diminished at longer durations, an effect that was also revealed in the latency data. Results are interpreted within a continuous-flow conceptualization of visual processing and are consistent with the hypothesis that older adults are slowed in the feature extraction process that underlies visual search.

Age differences in the useful field of view (UFOV) were examined by asking younger (mean age = 24 years) and older (mean age = 64 years) observers to search for two oriented line targets. These targets were presented at eccentricities ranging from 4 degrees to 14 degrees, and were embedded in either no distractors, homogeneous distractors, or heterogeneous distractors. Eye movements were recorded, along with reaction time (RT) and accuracy. The eye movement data indicated that older observers had more difficulty locating peripheral targets, particularly when they were embedded in heterogeneous distractors. Furthermore, the greater effects of eccentricity and distractor type found in the RT's of older adults were eliminated when age differences in saccade number were partialled out. These findings suggest that age differences in search are largely attributable to factors other than selective attention.

The contrast sensitivity function (CSF), although containing more information than traditional measures of acuity, has found difficulty gaining clinical acceptance. The hesitancy of clinicians to adopt the CSF stems, in part, from the fact that it is not as readily interpreted as is acuity. In order to facilitate such interpretation, five indices of spatial vision which are derivable from the CSF were examined in a sample of 287 persons aged 5 to 85 years. All indices were found to be both age-sensitive and strongly related to each other, but bandwidth of the CSF was chosen as a practical index for clinical settings. In a second study, acuity and CSF bandwidth were measured under 0 to +/- 1 D optical blur. It was found that the correction providing best acuity also maximized CSF bandwidth, and that bandwidth was more sensitive to optical blur than was acuity. Results support the assertion that CSF bandwidth is a readily interpreted index of spatial vision that can be measured efficiently within the context of clinical refraction.

Inhibition of return (IOR) occurs when people are slower to detect a target that appeared at a previously cued location. Prior research has shown that younger and older adults display similar amounts of IOR, but this research has not examined the time course of the process. Because elderly people may be slower to engage or disengage spatially based attention, the present experiment examined age differences in IOR at stimulus-onset asynchronies ranging from 50 ms to 3,000 ms. The results show that the peak magnitude of IOR was similar for younger and older adults, but the onset of IOR occurred approximately 300 ms later in elderly persons. Older adults also showed a greater degree of facilitation at shorter stimulus-onset asynchronies. The results suggest that there is a change in the temporal dynamics of inhibition that occurs with age.

Structural equation modeling was used to assess the utility of the sensorineural model of contrast sensitivity proposed by Sekuler et al. [Vision Res. 24, 689 (1984)] to account for spatial vision in adulthood. In Study 1, visual acuity and contrast sensitivity (1.5-18 c/deg) were measured in 84 people between the ages of 19 and 81 yr. No three-filter model fitted the data well. Although a two-filter model was associated with good fit indices, parameter estimates for both filters were inconsistent with physiological and behavioral data. In Study 2, acuity and contrast sensitivity (1.5-18 c/deg) were assessed in 95 observers between the ages of 23 and 73 yr. All measures were gathered once per month over a three-month period. The Sekuler et al. three-filter model did not fit the data from any time of measure, but a two-filter, bandpass model provided a consistent and excellent fit for all three waves. The model suggests that age-related change in the neural mechanisms underlying contrast sensitivity is minimal once acuity is controlled. Discrepancies between this conclusion and that reported by Sekuler et al. may be related to test type, psychophysical method, reliability, and sample selection.

Contrast sensitivity was measured at near using the Vistech 6000 Contrast Test System (VCTS) in 287 persons aged 4 to 87 years. Obtained data compared well with those previously reported for the Vistech charts. Results indicate an age-related loss in sensitivity to intermediate and higher spatial frequencies. This is consistent with the age trends observed using other methods for measuring contrast sensitivity functions (CSFs). However, the Vistech charts yield contrast sensitivity values which are lower than those obtained previously with the Nicolet system. These between-method differences are greatest at lower spatial frequencies, and are attributed to the small number of grating cycles in the Vistech charts. The data are used to develop provisional age norms for the Vistech charts which allow the assessment of an individual's performance relative to their age cohort. Recommendations for use and future development of the Vistech charts are also given.

Commonality of associative response provides an index of the organization of semantic memory. The present study investigated age differences in semantic organization by comparing commonality of associative response. Thirty young (M=20 yrs) and 30 old (M = 72 yrs) adults gave free associations to single stimulus words of high or low linguistic frequency. Controlling statistically for education and verbal skills, it was determined that there were no age differences in the commonality or variability of associates. Results are discussed in reference to developmental trends in the organization of semantic memory.

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.