Multi-target visual search organisation across the lifespan: cancellation task performance in a large and demographically stratified sample of healthy adults

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.

Organization measures in the Enhanced Baking Tray Task

Introduction

The ecological assessment and the analysis of spatial organization behaviors, like the organization of objects in an empty space, in clinical and neurotypical conditions, is crucial. The Enhanced-Baking Tray Task (E-BTT) is as simple as that – placing objects inside a frame as evenly as possible, as if they were “cookies” to be baked in the oven. The E-BTT is the enhanced version of a task for neglect assessment, the Baking Tray Task, and has the advantage to register the coordinates of each object and their temporal order, meaning that it is easy to reconstruct the sequence of their placement. This sequence could be further analyzed, and, in this paper, we aim to do that with a series of indexes. Moreover, since they investigate the visual search organization of the sequence itself, their validity will be tested with a convergent measure of subjective organization.

Methods

Therefore, we asked 100 observers (76 women) to evaluate the subjective organization of each of 97 E-BTT plots, on a scale that ranged from 0 = not at all to 100 = well organized.

Results

A multiple regression model showed a significant association between subjective organization ratings (dependent variable) and Intersection rate, Total time of performance and distance to both optimal sequences (independent variables).

Discussion

Therefore the above-mentioned indexes can be considered measures of the overall organization in the E-BTT.

Statistical power for cluster analysis

BACKGROUND

Cluster algorithms are gaining in popularity in biomedical research due to their compelling ability to identify discrete subgroups in data, and their increasing accessibility in mainstream software. While guidelines exist for algorithm selection and outcome evaluation, there are no firmly established ways of computing a priori statistical power for cluster analysis. Here, we estimated power and classification accuracy for common analysis pipelines through simulation. We systematically varied subgroup size, number, separation (effect size), and covariance structure. We then subjected generated datasets to dimensionality reduction approaches (none, multi-dimensional scaling, or uniform manifold approximation and projection) and cluster algorithms (k-means, agglomerative hierarchical clustering with Ward or average linkage and Euclidean or cosine distance, HDBSCAN). Finally, we directly compared the statistical power of discrete (k-means), "fuzzy" (c-means), and finite mixture modelling approaches (which include latent class analysis and latent profile analysis).

RESULTS

We found that clustering outcomes were driven by large effect sizes or the accumulation of many smaller effects across features, and were mostly unaffected by differences in covariance structure. Sufficient statistical power was achieved with relatively small samples (N = 20 per subgroup), provided cluster separation is large (Δ = 4). Finally, we demonstrated that fuzzy clustering can provide a more parsimonious and powerful alternative for identifying separable multivariate normal distributions, particularly those with slightly lower centroid separation (Δ = 3).

CONCLUSIONS

Traditional intuitions about statistical power only partially apply to cluster analysis: increasing the number of participants above a sufficient sample size did not improve power, but effect size was crucial. Notably, for the popular dimensionality reduction and clustering algorithms tested here, power was only satisfactory for relatively large effect sizes (clear separation between subgroups). Fuzzy clustering provided higher power in multivariate normal distributions. Overall, we recommend that researchers (1) only apply cluster analysis when large subgroup separation is expected, (2) aim for sample sizes of N = 20 to N = 30 per expected subgroup, (3) use multi-dimensional scaling to improve cluster separation, and (4) use fuzzy clustering or mixture modelling approaches that are more powerful and more parsimonious with partially overlapping multivariate normal distributions.

UCancellation: A new mobile measure of selective attention and concentration

Measuring selective attention in a speeded task can provide valuable insight into the concentration ability of an individual, and can inform neuropsychological assessment of attention in aging, traumatic brain injury, and in various psychiatric disorders. There are only a few tools to measure selective attention that are freely available, psychometrically validated, and can be used flexibly both for in-person and remote assessment. To address this gap, we developed a self-administrable, mobile-based test called “UCancellation” (University of California Cancellation), which was designed to assess selective attention and concentration and has two stimulus sets: Letters and Pictures. UCancellation takes less than 7 minutes to complete, is automatically scored, has multiple forms to allow repeated testing, and is compatible with a variety of iOS and Android devices. Here we report the results of a study that examined parallel-test reliability and convergent validity of UCancellation in a sample of 104 college students. UCancellation Letters and Pictures showed adequate parallel test reliability (r = .71–.83, p < 0.01) and internal consistency (ɑ = .73–.91). It also showed convergent validity with another widely used cancellation task, d2 Test of Attention (r = .43–.59, p < 0.01), and predicted performance on a cognitive control composite (r = .34–.41, p < 0.05). These results suggest that UCancellation is a valid test of selective attention and inhibitory control, which warrants further data collection to establish norms.

Direct and indirect links between children's socio-economic status and education: pathways via mental health, attitude, and cognition

A child's socio-economic environment can profoundly affect their development. While existing literature focusses on simplified metrics and pair-wise relations between few variables, we aimed to capture complex interrelationships between several relevant domains using a broad assessment of 519 children aged 7-9 years. Our analyses comprised three multivariate techniques that complimented each other, and worked at different levels of granularity. First, an exploratory factor analysis (principal component analysis followed by varimax rotation) revealed that our sample varied along continuous dimensions of cognition, attitude and mental health (from parallel analysis); with potentially emerging dimensions speed and socio-economic status (passed Kaiser's criterion). Second, k-means cluster analysis showed that children did not group into discrete phenotypes. Third, a network analysis on the basis of bootstrapped partial correlations (confirmed by both cross-validated LASSO and multiple comparisons correction of binarised connection probabilities) uncovered how our developmental measures interconnected: educational outcomes (reading and maths fluency) were directly related to cognition (short-term memory, number sense, processing speed, inhibition). By contrast, mental health (anxiety and depression symptoms) and attitudes (conscientiousness, grit, growth mindset) showed indirect relationships with educational outcomes via cognition. Finally, socio-economic factors (neighbourhood deprivation, family affluence) related directly to educational outcomes, cognition, mental health, and even grit. In sum, cognition is a central cog through which mental health and attitude relate to educational outcomes. However, through direct relations with all components of developmental outcomes, socio-economic status acts as a great 'unequaliser'.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12144-021-02232-2.

The development of foraging organization

In foraging tasks, multiple targets must be found within a single display. The targets can be of one or more types, typically surrounded by numerous distractors. Visual attention has traditionally been studied with single target search tasks, but adding more targets to the search display results in several additional measures of interest, such as how attention is oriented to different features and locations over time. We measured foraging among five age groups: Children in Grades 1, 4, 7, and 10, as well as adults, using both simple feature foraging tasks and more challenging conjunction foraging tasks, with two target types per task. We assessed participants' foraging organization, or systematicity when selecting all the targets within the foraging display, on four measures: Intertarget distance, number of intersections, best-r, and the percentage above optimal path length (PAO). We found that foraging organization increases with age, in both simple feature-based foraging and more complex foraging for targets defined by feature conjunctions, and that feature foraging was more organized than conjunction foraging. Separate analyses for different target types indicated that children's, and to some extent adults', conjunction foraging consisted of two relatively organized foraging paths through the display where one target type is exhaustively selected before the other target type is selected. Lastly, we found that the development of foraging organization is closely related to the development of other foraging measures. Our results suggest that measuring foraging organization is a promising avenue for further research into the development of visual orienting.

Race/Ethnic Differences in Social Resources as Cognitive Risk and Protective Factors

Overall social network size, often the sum of common lifetime relationships, including children, family, and friends, has been linked to cognitive impairment and Alzheimer's Disease. However, little research has examined the association between network size composition and cognitive function in middle-aged and older adults in the context of race/ethnicity. We investigated the associations between the number of close children, family, and friends independently with executive function (EF) and memory across a subsample of non-Hispanic Black, Hispanic, and non-Hispanic White participants who completed the Health and Retirement Study Harmonized Cognitive Assessment Protocol (N = 2,395). We found that network size composition was more closely linked to EF than memory and that these associations varied by race/ethnicity. Specifically, the strongest associations existed between EF and quadratic estimates of the number of close children of non-Hispanic Black participants, and number of close family members for Hispanic participants. Among Black participants, a curvilinear relationship indicated that two close children were associated with greater EF, while a smaller or larger number of close children were associated with lower EF. On the other hand, among Hispanic participants, higher EF was associated with fewer (0-1) and greater (4-5+) numbers of family member contacts. Overall, these results indicate that examining children, family, and friends independently may be more useful than the common practice of aggregation of overall network size, especially in the context of race/ethnicity.