Dataset Information

A search-by-clusters model of visual search: fits to data from younger and older adults.

ABSTRACT:

Objectives

This study aims to specify the processing operations underlying age-related differences in the speed and accuracy of visual search in a mathematical model.

Method

Eighteen older and 18 young adults searched for a predesignated target within 24-degree visual arrays containing distractors. Targets were systematically placed in regions that extended 2.5, 5.0, 7.5, and 10 degrees from center. Data were fitted to several versions of a mathematical model in which it was assumed that target search proceeds from the center fixation to peripheral areas in a succession of visual inspections of clusters until the target is located and that clusters can vary in size in response to search difficulty.

Results

Eccentricity effects on latencies and errors were larger for older adults than for younger adults, especially in the hardest search condition. The best-fitting version of the "search-by-clusters" model accounted for an average of 98.4% and 95.4% of the variance in the young and older adults, respectively. The resulting time, accuracy, and cluster parameters behaved plausibly in each of the 36 data sets.

Conclusions

A quantitative model that specified how individuals searched for targets in large arrays accurately predicted the search times and accuracies of younger and older adults.

SUBMITTER: Hoyer WJ

PROVIDER: S-EPMC3132265 | biostudies-literature | 2011 Jul

REPOSITORIES: biostudies-literature

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Publications

A search-by-clusters model of visual search: fits to data from younger and older adults.

Hoyer William J WJ Cerella John J Buchler Norbou G NG

The journals of gerontology. Series B, Psychological sciences and social sciences 20110331 4

<h4>Objectives</h4>This study aims to specify the processing operations underlying age-related differences in the speed and accuracy of visual search in a mathematical model.<h4>Method</h4>Eighteen older and 18 young adults searched for a predesignated target within 24-degree visual arrays containing distractors. Targets were systematically placed in regions that extended 2.5, 5.0, 7.5, and 10 degrees from center. Data were fitted to several versions of a mathematical model in which it was assum ...[more]

PMID: 21459772

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Project description:Self-motion perception (e.g., when walking/driving) relies on the integration of multiple sensory cues including visual, vestibular, and proprioceptive signals. Changes in the efficacy of multisensory integration have been observed in older adults (OA), which can sometimes lead to errors in perceptual judgments and have been associated with functional declines such as increased falls risk. The objectives of this study were to determine whether passive, visual-vestibular self-motion heading perception could be improved by providing feedback during multisensory training, and whether training-related effects might be more apparent in OAs vs. younger adults (YA). We also investigated the extent to which training might transfer to improved standing-balance. OAs and YAs were passively translated and asked to judge their direction of heading relative to straight-ahead (left/right). Each participant completed three conditions: (1) vestibular-only (passive physical motion in the dark), (2) visual-only (cloud-of-dots display), and (3) bimodal (congruent vestibular and visual stimulation). Measures of heading precision and bias were obtained for each condition. Over the course of 3 days, participants were asked to make bimodal heading judgments and were provided with feedback ("correct"/"incorrect") on 900 training trials. Post-training, participants' biases, and precision in all three sensory conditions (vestibular, visual, bimodal), and their standing-balance performance, were assessed. Results demonstrated improved overall precision (i.e., reduced JNDs) in heading perception after training. Pre- vs. post-training difference scores showed that improvements in JNDs were only found in the visual-only condition. Particularly notable is that 27% of OAs initially could not discriminate their heading at all in the visual-only condition pre-training, but subsequently obtained thresholds in the visual-only condition post-training that were similar to those of the other participants. While OAs seemed to show optimal integration pre- and post-training (i.e., did not show significant differences between predicted and observed JNDs), YAs only showed optimal integration post-training. There were no significant effects of training for bimodal or vestibular-only heading estimates, nor standing-balance performance. These results indicate that it may be possible to improve unimodal (visual) heading perception using a multisensory (visual-vestibular) training paradigm. The results may also help to inform interventions targeting tasks for which effective self-motion perception is important.

Project description:Differences in inhibitory ability between older (64-79 years, N = 24) and younger adults (18-26 years, N = 24) were investigated using a diffusion model analysis. Participants performed a task-switching paradigm that allows assessing n-2 task repetition costs, reflecting inhibitory control on the level of tasks, as well as n-1 response-repetition costs, reflecting inhibitory control on the level of responses. N-2 task repetition costs were of similar size in both age groups. Diffusion model analysis revealed that for both younger and older adults, drift rate parameters were smaller in the inhibition condition relative to the control condition, consistent with the idea that persisting task inhibition slows down response selection. Moreover, there was preliminary evidence for task inhibition effects in threshold separation and non-decision time in the older, but not the younger adults, suggesting that older adults might apply different strategies when dealing with persisting task inhibition. N-1 response-repetition costs in mean RT were larger in older than younger adults, but in mean error rates tended to be larger in younger than older adults. Diffusion-model analysis revealed longer non-decision times in response repetitions than response switches in both age groups, consistent with the idea that motor processes take longer in response repetitions than response switches due to persisting response inhibition of a previously executed response. The data also revealed age-related differences in overall performance: Older adults responded more slowly and more accurately than young adults, which was reflected by a higher threshold separation parameter in diffusion model analysis. Moreover, older adults showed larger non-decision times and higher variability in non-decision time than young adults, possibly reflecting slower and more variable motor processes. In contrast, overall drift rate did not differ between older and younger adults. Taken together, diffusion model analysis revealed differences in overall performance between the age groups, as well as preliminary evidence for age differences in dealing with task inhibition, but no evidence for an inhibitory deficit in older age.

Dataset Information

A search-by-clusters model of visual search: fits to data from younger and older adults.

Objectives

Method

Results

Conclusions

Publications

A search-by-clusters model of visual search: fits to data from younger and older adults.

Similar Datasets

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