Vision-fair neuropsychological assessment in normal aging, Parkinson's disease and Alzheimer's disease

We examined performance of healthy older and younger adults and individuals with Alzheimer's disease (AD) and Parkinson's disease (PD) on digit cancellation, a task putatively sensitive to cognitive impairment, but possibly affected by visual impairment, particularly in contrast sensitivity. Critical contrast thresholds were established to create custom stimulus arrays that were proximally matched across individuals. Age- and PD-related differences in search were fully accounted for by the sensory deficit. Increased contrast benefited AD patients, but could not override cognitive impairment. We conclude that visually fair neuropsychological testing can effectively compensate for normal age- and PD-related visual changes that affect cognitive performance. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

Age differences in visual search: target and distractor learning.

Age differences in a semantic category visual search task were investigated to determine whether the age effects were due to target learning deficits, distractor learning deficits, or a combination thereof. Twelve young (mean age 20) and 12 older (mean age 70) adults received 2,400 trials each in consistent and varied versions of the search task. Following training, a series of transfer-reversal manipulations allowed the assessment of target learning and distractor learning both in isolation and in combination. The pattern of data suggests that older adults have a deficit in their ability to increase the attention-attraction strength of targets and to decrease the attention-attraction strength of distractors. The results are interpreted in terms of a strength-based framework of visual search performance.     

Now you see it, now you don't: evidence for age-dependent and age-independent cross-modal distraction

Age-related deficits in selective attention have often been demonstrated in the visual modality and, to a lesser extent, in the auditory modality. In contrast, a mounting body of evidence has suggested that cross-modal selective attention is intact in aging, especially in visual tasks that require ignoring the auditory modality. Our goal in this study was to investigate age-related differences in the ability to ignore cross-modal auditory and visual distraction and to assess the role of cognitive control demands thereby. In a set of two experiments, 30 young (mean age = 23.3 years) and 30 older adults (mean age = 67.7 years) performed a visual and an auditory n-back task (0 ≤ n ≤ 2), with and without cross-modal distraction. The results show an asymmetry in cross-modal distraction as a function of sensory modality and age: Whereas auditory distraction did not disrupt performance on the visual task in either age group, visual distraction disrupted performance on the auditory task in both age groups. Most important, however, visual distraction was disproportionately larger in older adults. These results suggest that age-related distraction is modality dependent, such that suppression of cross-modal auditory distraction is preserved and suppression of cross-modal visual distraction is impaired in aging.     

Bingo! Externally supported performance intervention for deficient visual search in normal aging, Parkinson's disease, and Alzheimer's disease

External support may improve task performance regardless of an individual's ability to compensate for cognitive deficits through internally generated mechanisms. We investigated if performance of a complex, familiar visual search task (the game of bingo) could be enhanced in groups with suboptimal vision by providing external support through manipulation of task stimuli. Participants were 19 younger adults, 14 individuals with probable Alzheimer's disease (AD), 13 AD-matched healthy adults, 17 non-demented individuals with Parkinson's disease (PD), and 20 PD-matched healthy adults. We varied stimulus contrast, size, and visual complexity during game play. The externally supported performance interventions of increased stimulus size and decreased complexity resulted in improvements in performance by all groups. AD also obtained benefit from increasing contrast, presumably by compensating for their contrast sensitivity deficit. The general finding of improved performance across healthy and afflicted groups suggests the value of visual support as an easy-to-apply intervention to enhance cognitive performance.     

Age differences in the distractor-ratio effect as a function of contrast level

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.     

Decomposing adult age differences in symbol arithmetic

A componential analysis was conducted to determine the locus of adult age differences in symbol arithmetic. Measures of the duration of two proposed components, substitution of digits for symbols and the addition or subtraction of the digits resulting from these substitutions, were obtained from 52 young adults and 52 older adults. Tests of working memory, perceptual speed, motor speed, and associative learning were also administered to all subjects. The results were most consistent with an interpretation postulating that the speed of many different cognitive processes decreases with increased age. Considerable age-related variance remained in the measures of symbol arithmetic performance after statistical control of working memory and associative learning performance, casting doubt on alternative hypotheses of the source of age-related differences in this task.     

Age Differences in the Distractor-Ratio Effect as a Function of Contrast Level

ABSTRACT

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 × 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.     

Information processing components of substitution test performance

Although substitution tests have been included in tests of intelligence for years, the underlying abilities they measure have still not been clearly determined. This study used componential analysis to investigate the information-processing components underlying substitution test performance. The bases of sex and age differences were also of interest. One hundred subjects from each of three age groups (9–11, 18–25, and 60–89 years) were tested.The componential analysis found that substitution tests measure perceptual speed and, to a lesser extent, memory ability and writing speed. The component “Stimulus Orientation, Response Initiation, and Execution” was related to substitution test performance in the sample of children and the sample of older adults but not in the sample of younger adults. Verbal ability was not significantly related to substitution test performance in the two younger samples but was strongly related to substitution performance in the oldest sample. Although females outperformed males on the Symbol Digit Test, males did as well as females on the computerized tasks. Apparently, sex differences in substitution test performance cannot be explained by the components of the test measured here.     

The effect of discordant sensory information in graphic production: two distinct subject groups

The present study investigated the underlying processes used to cope with discordant sensory information induced in a mirror-drawing task. Two experiments were carried out in which adults copied simple geometrical figures made up of either horizontal and vertical segments or oblique segments meeting at a right angle in both a normal and a mirror condition. Experiment 1 identified individual differences in relation to preferred graphic movement directions; some subjects preserved the visual directions that occurred in normal drawing by reversing the direction of drawing movements (perceived-direction group), while others preserved normal drawing directions that produced reversed visual directions (performed-direction group). Experiment 2 was performed to elucidate whether these two distinct behaviors resulted from different strategies used to cope with visuo-proprioceptive discordances. The main results showed that preference for the perceived directions led to longer pauses, slower movement velocity, greater movement dysfluency, and greater spatial orientation accuracy. By contrast, longer reaction time and greater angular accuracy characterized performance in the performed-direction group. These results were interpreted as indicating that two distinct information-processing strategies can be used when resolving sensory discordance in graphic production.     

Age and the selectivity of visual information processing

Two experiments were conducted to assess age differences in the selectivity of visual information processing. Selectivity was measured by the amount of interference caused by nontarget letters when subjects detected a target letter in a visual display. In both experiments, young and elderly groups participated in search and nonsearch conditions; in the search condition targets appeared anywhere in the display, whereas in the nonsearch condition targets were confined to the center position of the display. In the first experiment, subjects were assigned to either condition for two sessions of testing, and in the second experiment each subject participated in both conditions. In both experiments nontargets produced larger interference effects for old compared to young adults in the search condition but not in the nonsearch condition. The obtained pattern of age effects could not be explained by age-related reductions in parafoveal acuity. The findings indicate that the magnitude of divided-attention deficit increases with age, whereas focused-attention deficits are unaffected by aging.     

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.     

The enhanced Simon effect for older adults is reduced when the irrelevant location information is conveyed by an accessory stimulus

The Simon effect, better performance when irrelevant stimulus location corresponds with the response location than when it does not, typically is larger for older than younger adults. However, Simon and Pouraghabagher [Simon, R. J., & Pouraghabagher, A. R. (1978). The effect of aging on the stages of processing in a choice reaction time task. Journal of Gerontology, 33, 553-561] found no age difference using an accessory-stimulus Simon task in which the relevant dimension was the color of a visual stimulus and the irrelevant dimension the location of a tone. Experiment 1 confirmed that older adults show a larger Simon effect than younger adults for the visual Simon task and that this age-related deficit is reduced or eliminated for the auditory-accessory task. Experiment 2 provided evidence suggesting that a small part of the age-related deficit in the visual Simon task is due to having to code the location of the relevant stimulus, but Experiment 3 showed that the majority of the deficit is due to the relevant and irrelevant information being conveyed by the same stimulus. Reaction-time distribution analyses show similar functions for younger and older adults, suggesting that the time course of activation is similar for both age groups.     

Age-related differences in the use of background layout in visual search

The effect of background layout on visual search performance, and more specifically on the tendency to refixate previously inspected locations and objects, was investigated. Older and younger adults performed a search task in which a background layout or landmark was present or absent in a gaze contingent visual search paradigm. Regardless of age, participants demonstrated fewer refixations when landmarks were present, with older adults showing a larger landmark advantage. This visual search advantage did not come at the cost of saccadic latency. Furthermore, the visual search performance advantage obtained in the presence of a background layout or landmark was observed both for individuals with small and large memory spans.     

The effects of aging on the working memory processes of multimodal information

Normal aging is associated with deficits in working memory processes. However, the majority of research has focused on storage or inhibitory processes using unimodal paradigms, without addressing their relationships using different sensory modalities. Hence, we pursued two objectives. First, was to examine the effects of aging on storage and inhibitory processes. Second, was to evaluate aging effects on multisensory integration of visual and auditory stimuli. To this end, young and older participants performed a multimodal task for visual and auditory pairs of stimuli with increasing memory load at encoding and interference during retention. Our results showed an age-related increased vulnerability to interrupting and distracting interference reflecting inhibitory deficits related to the off-line reactivation and on-line suppression of relevant and irrelevant information, respectively. Storage capacity was impaired with increasing task demands in both age groups. Additionally, older adults showed a deficit in multisensory integration, with poorer performance for new visual compared to new auditory information.     

视知觉压力在基本心理能力老化中的作用

信息降格说认为, 感觉功能老化使认知系统难以获得良好的信息输入, 并必须牺牲有限的认知资源获得更好的刺激信息, 使能用于认知加工的资源不足, 造成认知老化。为探讨感觉功能对基本心理能力老化的作用, 该研究采用2(年龄组：年轻、老年组)×4(视知觉压力水平：高、中、低、无噪音)的混合设计, 考察年轻、老年组在相同视知觉压力下基本心理能力的年龄差异。结果发现和无噪音条件相比, 相同视知觉压力下基本心理能力(数字能力、归纳推理能力)的年龄差异减小, 甚至消失, 一定程度上支持信息降格说。视觉功能衰退可能是影响基本心理能力老化的重要因素, 但这种作用受认知资源的调节。     

Do working-memory executive components mediate the effects of age on strategy selection or on strategy execution? Insights from arithmetic problem solving

Younger and older adults performed an inequality verification task (7+6 < 15, Yes/No?) in a control condition and in a dual-task condition where they simultaneously performed an executive-component task. Arithmetic-problem characteristics were manipulated in order to test strategy selection (i.e., choice of appropriate strategies in order to improve performance) and strategy execution (i.e., performance of the cognitive processes involved in each strategy). Results revealed that strategy selection changes with age: Older adults mainly selected one type of strategies in contrast to younger adults who used several types of strategies. These age-related changes were similar in the control and dual-task conditions. Strategy execution also changed with age, as shown by larger age-related differences on hardest problems. These age-related changes were larger in the dual-task condition, compared to the control condition. This impact of executive components as mediator of age-related changes depended on general age-related slowing. We discuss these findings in order to further understand the effects of age on arithmetic performance.     

Exploring the specificity of age-related differences in theory of mind tasks

Tasks assessing theory of mind (ToM) and non-mental state control tasks were administered to young and older adults to examine previous contradictory findings about age differences in mental state decoding. Age differences were found on a verbal ToM task after controlling for vocabulary levels. Older adults achieved significantly lower scores than did younger adults on static and dynamic visual ToM tasks, and a similar pattern was found on non-ToM control tasks. Rather than a specific ToM deficit, older adults exhibited a more general impairment in the ability to decode cues from verbal and visual information about people.     

Effects of age on listening and postural control during realistic multi-tasking conditions

Successful performance of balance-related activities requires the effective integration of sensory, cognitive, and motor processes that can be affected by age-related changes. Of these age-related sensory changes, the effects of declines in hearing on balance have not been well-studied despite the fact that hearing loss has now been acknowledged as a significant risk factor for falls. The goal of this study was to evaluate age-related differences in a “standing while listening” task within increasingly challenging conditions resembling those that are often encountered in realistic, everyday situations.This study used a dual-task paradigm in an immersive Virtual Reality street scene setting in which postural load (firm, compliant), listening load (number of talkers), and visual load (eyes open/closed) were manipulated. A multi-talker divided attention listening task was used. Postural performance was assessed using center of pressure (COP) path length, while listening performance was assessed using spoken word recognition accuracy.Results demonstrated that age-related differences were observed in postural performance when postural demands were the highest and in listening performance when listening demands were the highest. Proportional dual-task costs were more pronounced for postural task performance compared to listening task performance and were more pronounced for older compared to younger adults. Postural dual-task costs increased as a function of increasing listening loads. Removal of visual information improved listening task performance across both groups and reduced the dual-task costs to listening in older adults when listening demands were highest (resulting in dual-task benefits).Taken together, the findings support previously documented age-related declines in postural control and auditory processing, demonstrate that increasing listening demands may result in poorer balance, particularly in older adults, and provide additional insights into the interactive effects of age-related declines when sensory, motor, and cognitive challenges are incremented factorially.     

汉语发展性阅读障碍儿童的视知觉学习*

研究采用知觉学习经典范式中的视觉搜索任务探讨汉语发展性阅读障碍儿童的知觉学习过程。研究考察了阅读障碍儿童与正常儿童在简单搜索任务、复杂搜索任务和限制时间的复杂搜索任务上的知觉学习特点。结果发现,阅读障碍儿童在复杂搜索任务中初始搜索时间显著长于正常控制组;在限制时间的复杂搜索任务中更进一步发现阅读障碍儿童的反应正确率显著低于正常控制组儿童;而且两组儿童视觉搜索任务的正确率与汉语阅读的识字量成绩存在显著相关。上述结果表明,汉语发展性阅读障碍儿童存在复杂搜索的知觉学习缺陷,这种缺陷可能在某种程度上与儿童的阅读技能发展有关。     

Adaptation to direction-dependent visuo-motor rotations and its decay in younger and older adults

We studied adaptation to a direction-dependent visuo-motor rotation in adults of early and late working age. For hand movements to the right, visual motion of the cursor on a monitor was rotated clockwise, for forward movements rotation of the cursor motion was zero, and for directions in-between rotation was intermediate. In contrast to previous studies, in which adaptation was more difficult (larger visuo-motor rotation, larger number of targets during practice) and the older age group was of higher age, we found no age-related deficit of adaptation. However, consistent with previous studies we found an age-related impairment of explicit knowledge of the visuo-motor rotation and no age-related differences of aftereffects. Across periods of not performing the task for 24 h and of performing the task for a prolonged period of time without visual feedback, we observed a decay of adaptation which did not depend on age. The present findings cast doubts on the prevalent interpretation of age-related impairments of adaptation in the absence of age-related changes of aftereffects as resulting from intentional strategic corrections, which become less efficient at higher age.