Biomedical subjects

Charles T Scialfa

Publications and source records attributed to Charles T Scialfa.

13 recordsLinked to original sources

PubMed2006

Aging, memory and visual search.

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.

Adult↗

PubMed2006

Does impaired executive functioning differentially impact verbal memory measures in older adults with suspected dementia?

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.

Aged↗

PubMed2005

Examining task difficulty and the time course of inhibition of return: detecting perceptually degraded targets.

The ability to efficiently direct visual attention to salient features in the environment is a critical function of the visual system. The finding that people are slower to detect a target that appears at a previously cued location is thought to reflect a mechanism known as inhibition of return (IOR). Past research has shown that difficult target discriminations result in a greater amount of time needed to inhibit previously attended locations (i.e., a delayed onset of inhibition), suggesting that task difficulty plays a critical role in the allocation of attention. In this study, IOR was measured at a wide range of SOAs while participants detected either a perceptually degraded target or a standard, high luminance target. When responses were made to a perceptually degraded target, the time course of IOR was delayed by approximately 250 ms (relative to the control group), suggesting that the difficulty in detecting targets also influences the allocation of attention. The results are consistent with the notion that IOR is not simply a reflexive subcortical mechanism but rather involves top-down attentional control settings.

Adult↗

PubMed2005

Predictors of web navigation performance in a life span sample of adults.

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.

Adult↗

PubMed2004

Age differences in feature selection in triple conjunction search.

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.

Adult↗

PubMed2004

Varied-mapping conjunction search: evidence for rule-based learning.

Five experiments were carried out to examine whether top-down processes can aid search, even when targets and distractors are variably mapped. Experiments 1a and 1b determined that effortless VM search can be obtained in Contrast Polarity X Orientation and Color X Orientation conjunction search when one feature dimension remains consistently mapped across blocks. Experiment 2 showed that efficient VM search is possible when both dimensions are variably mapped. In Experiment 3, efficient VM search was found when target-distractor reversals occurred on a trial-wise basis. Experiments 4 and 5 found that VM search deteriorates when target identity is not known prior to display onset. These studies demonstrate the role of top-down mechanisms in the development of efficient VM search and present several challenges to strength-theoretic views on the mechanisms underlying automaticity.

Adult↗

PubMed2004

Age differences in search of web pages: the effects of link size, link number, and clutter.

Reaction time, eye movements, and errors were measured during visual search of Web pages to determine age-related differences in performance as a function of link size, link number, link location, and clutter. Participants (15 young adults, M = 23 years; 14 older adults, M = 57 years) searched Web pages for target links that varied from trial to trial. During one half of the trials, links were enlarged from 10-point to 12-point font. Target location was distributed among the left, center, and bottom portions of the screen. Clutter was manipulated according to the percentage of used space, including graphics and text, and the number of potentially distracting nontarget links was varied. Increased link size improved performance, whereas increased clutter and links hampered search, especially for older adults. Results also showed that links located in the left region of the page were found most easily. Actual or potential applications of this research include Web site design to increase usability, particularly for older adults.

Adult↗

PubMed2004

Age differences in visual search for traffic signs during a simulated conversation.

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.

Accidents, Traffic↗

PubMed2003

Plasticity of feature-based selection in triple-conjunction search.

Two experiments examined the disruption of feature-based selection in triple-conjunction search at multiple target transfers. In Experiment 1, after 10 training sessions, a new target possessing previous distractor features was introduced. This produced disruption in RT and fixation number, but no disruption in feature-based selection. Specifically, there was a tendency to fixate objects sharing the target's contrast polarity and shape and this did not change even upon transfer to the new target. In Experiment 2, 30 training sessions were provided with three target transfers. At the first transfer, the results replicated Experiment 1. Subsequent transfers did not produce disruption on any measure. These findings are discussed in terms of strength theory, Guided Search, rule-based approaches to perceptual learning, and the area activation model.

Adult↗

PubMed2003

Adult age differences in the time course of inhibition of return.

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.

Adult↗

PubMed2002

The role of sensory factors in cognitive aging research.

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.

Aged↗

PubMed2002

Age, skill transfer, and conjunction search.

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.

Adult↗

PubMed2002

Structural modeling of contrast sensitivity in adulthood.

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.

Adult↗