Age-related changes in visual search: manipulation of colour cues based on cone contrast and opponent modulation space

Aging effects on extrapersonal (far-space) attention: cancellation and line bisection performance from 179 healthy adults

Assessment of cognitive impairments is a vital part of clinical practice. Cancellation (visual search) and line bisection are commonly used tasks to assess visuospatial attention. Despite the fact visuospatial attention is engaged in both near (within reach) and far-space (out of reach), most studies have been conducted in near-space alone. Moreover, despite their use in clinical practice, it is unclear whether cancellation and bisection tasks are related. Here, we investigated the impact of aging on cancellation and line bisection performance in far-space in a large healthy sample. We provide preliminary age-graded norms for assessing visuospatial attention in far-space calculated from a sample of 179 healthy adults, between the ages of 18-94 (mean age = 49.29). Cancellation and line bisection were presented on a large screen in far-space and completed using a wireless remote. Aging was accompanied by longer task duration for both tasks, slower search speed and poorer quality of search. However, there was no significant effect of aging on line bisection error. There was a significant correlation between the two tasks in that longer task duration in line bisection was associated with slower search speed and poorer quality of search. Overall, participants presented a leftward bias during cancellation and line bisection akin to pseudoneglect. Moreover, we found that irrespective of age, search speed was faster in males than females. We offer novel evidence that performance on cancellation and line bisection tasks are related to one another in far-space, but are also sensitive to age-related decline, and even sex differences.

The Effect of Spatial Uncertainty on Visual Search in Older School-Aged Children with and without ADHD

OBJECTIVE

Numerous studies support that simple visual search tests may not be sufficient to differentiate children with and without attention-deficit/hyperactivity disorder (ADHD), especially for older school-aged children. This study aimed to explore whether the high spatial uncertainty visual search tasks can effectively discriminate older school-aged children with ADHD from their typically developing (TD) peers.

METHOD

In a randomized, two-period crossover design, 122 school-aged children (61 ADHD and 61 TD subjects), aged 10-12 years old, were measured using comparable visual search tasks with structured and unstructured layouts.

RESULTS

First, the discriminant effectiveness of unstructured visual search tasks, which are associated with high-level spatial uncertainty, is superior to structured ones. Second, combining accuracy and speed into a Q score is a more sensitive measure than accuracy or time calculated alone in visual search tasks. A more in-depth ROC analysis showed that all variables could accurately identify ADHD from their TD peers under unstructured visual search tasks, with the index of the Q score performing best (AUR = 0.956). Third, the development of detectability, which represents the ability to distinguish between target and non-target, is approaching maturity in 10-12-year-old children with ADHD. However, these children showed severe deficits in dealing with disorganized distractors when performing visual search tasks with high-level spatial uncertainty.

CONCLUSIONS

The findings of this study support that older school-aged children with ADHD demonstrate less efficient search performance than their TD peers in complex/difficult visual search tasks, especially under higher spatial uncertainty.

Differences in chromatic noise suppression of luminance contrast discrimination in young and elderly people

Aging causes impairment of contrast sensitivity and chromatic discrimination, leading to changes in the perceptual interactions between color and luminance information. We aimed to investigate the influence of chromatic noise on luminance contrast thresholds in young and older adults. Forty participants were divided equally into Young (29.6 ± 6.3-year-old) and Elderly Groups (57.8 ± 6.6-year-old). They performed a luminance contrast discrimination task in the presence of chromatic noise maskers using a mosaic stimulus in a mosaic background. Four chromatic noise masking protocols were applied (protan, deutan, tritan, and no-noise protocols). We found that luminance contrast thresholds were significantly elevated by the addition of chromatic noise in both age groups (P < 0.05). In the Elderly group, but not the younger group, thresholds obtained in the tritan protocol were lower than those obtained from protan and deutan protocols (P < 0.05). For all protocols, the luminance contrast thresholds of elderly participants were higher than in young people (P < 0.01). Tritan chromatic noise was less effective in inhibiting luminance discrimination in elderly participants.