Disorganized search on cancellation is not a consequence of neglect

Brief report of the reliability of a new method for scoring organizational approach on the Mesulam Cancellation Test

The Mesulam Cancellation Test is a low cost, quick measure used to screen for hemispatial inattention. The task is also useful for observing a patient's organizational approach. We developed a method to quantify the organizational strategy used by patients in completing this visual scanning task. In this study, we evaluated the reliability of the new method. Participants were 40 patients seen in an outpatient neuropsychology clinic. The 34 men, 5 women, and 1 transitioning individual had a mean age of 49 (SD = 13.94), and mean education of 13.59 years (SD = 2.15). Two raters blinded to patient information provided independent ratings of organization using our new scoring method. Scores ranged from 1 to 5 based on increasing organization. Cohen's weighted Kappa and Spearman's rank order correlation indicated good interrater reliability (Κ(weighted) = .84; rs = .89). The average absolute difference between the raters was .25 (SD = .54). We also found preliminary evidence for the validity of the organizational measure. This study supports the reliability of this new embedded measure of organization. A next step will be to gather normative data, to further establish its validity, and to assess the reliability of the scoring system with other cancellation tests.

The effects of visual and auditory synchrony on human foraging

Can synchrony in stimulation guide attention and aid perceptual performance? Here, in a series of three experiments, we tested the influence of visual and auditory synchrony on attentional selection during a novel human foraging task. Human foraging tasks are a recent extension of the classic visual search paradigm in which multiple targets must be located on a given trial, making it possible to capture a wide range of performance metrics. Experiment 1 was performed online, where the task was to forage for 10 (out of 20) vertical lines among 60 randomly oriented distractor lines that changed color between yellow and blue at random intervals. The targets either changed colors in visual synchrony or not. In another condition, a non-spatial sound additionally occurred synchronously with the color change of the targets. Experiment 2 was run in the laboratory (within-subjects) with the same design. When the targets changed color in visual synchrony, foraging times were significantly shorter than when they randomly changed colors, but there was no additional benefit for the sound synchrony, in contrast to predictions from the so-called "pip-and-pop" effect (Van der Burg et al., Journal of Experimental Psychology, 1053-1065, 2008). In Experiment 3, task difficulty was increased as participants foraged for as many 45° rotated lines as possible among lines of different orientations within 10 s, with the same synchrony conditions as in Experiments 1 and 2. Again, there was a large benefit of visual synchrony but no additional benefit for sound synchronization. Our results provide strong evidence that visual synchronization can guide attention during multiple target foraging. This likely reflects the local grouping of the synchronized targets. Importantly, there was no additional benefit for sound synchrony, even when the foraging task was quite difficult (Experiment 3).

The time course of visual foraging in the lifespan: Spatial scanning, organization search, and target processing

Visual foraging is a variant of visual search, consisting of searching for an undetermined number of targets among distractors (e.g., looking for various LEGO pieces in a box). Under non-exhaustive tasks, the observer scans the display, picking those targets needed, not necessarily all of them, before leaving the search. To understand how the organization of such natural foraging tasks works, several measures of spatial scanning and organization have been proposed in the exhaustive foraging literature: best-r, intertarget distances, PAO, and target intersections. In the present study, we apply these measures and new Bayesian indexes to determine how the time course of visual foraging is organized in a dynamic non-exhaustive paradigm. In a large sample of observers (279 participants, 4-25 years old), we compare feature and conjunction foraging and explore how factors like set size and time course, not previously tested in exhaustive foraging, might affect search organization in non-exhaustive dynamic tasks. The results replicate previous findings showing younger observers' searching being less organized, feature conditions being more organized than conjunction conditions, and organization leading to a more effective search. Interestingly, observers tend to be less organized as set size increases, and search is less organized within a patch as it advances in time: Search organization decreases when search termination is coming, suggesting organization measures as potential clues to understand quitting rules in search. Our results highlight the importance of studying search organization in foraging as a critical source of understanding complex cognitive processes in visual search.

Spatial neglect in the digital age: Influence of presentation format on patients' test behavior

OBJECTIVE

Computerized neglect tests could significantly deepen our disorder-specific knowledge by effortlessly providing additional behavioral markers that are hardly or not extractable from existing paper-and-pencil versions. This study investigated how testing format (paper versus digital), and screen size (small, medium, large) affect the Center of cancelation (CoC) in right-hemispheric stroke patients in the Letters and the Bells cancelation task. Our second objective was to determine whether a machine learning approach could reliably classify patients with and without neglect based on their search speed, search distance, and search strategy.

METHOD

We compared the CoC measure of right hemisphere stroke patients with neglect in two cancelation tasks across different formats and display sizes. In addition, we evaluated whether three additional parameters of search behavior that became available through digitization are neglect-specific behavioral markers.

RESULTS

Patients' CoC was not affected by test format or screen size. Additional search parameters demonstrated lower search speed, increased search distance, and a more strategic search for neglect patients than for control patients without neglect.

CONCLUSION

The CoC seems robust to both test digitization and display size adaptations. Machine learning classification based on the additional variables derived from computerized tests succeeded in distinguishing stroke patients with spatial neglect from those without. The investigated additional variables have the potential to aid in neglect diagnosis, in particular when the CoC cannot be validly assessed (e.g., when the test is not performed to completion).

Visual search organization in a cancellation task in developmental dyslexia

There is converging evidence that performance on visual search tasks, often assessed with cancellation tasks, is associated with performance on reading tasks. However, results have been inconsistent across studies dealing with developmental dyslexia. One limitation of previous research is that accuracy, rather than search strategies, was assessed. The present study is the first to investigate visual search strategies during a cancellation task in developmental dyslexia. Here, 24 dyslexic and 33 non-dyslexic children were included. Difficulties in visual search accuracy and organization were highlighted in the dyslexic group compared to the non-dyslexic group. Visual search patterns were also different if dyslexic children had more difficulties in the lexical or the sublexical reading route. While several questions remain to be addressed regarding the influence of other visual attentional processes on the relationship between visual search and reading, this study supports the use of visual search tasks in dyslexia assessment.

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.

Applying machine learning to dissociate between stroke patients and healthy controls using eye movement features obtained from a virtual reality task

Conventional neuropsychological tests do not represent the complex and dynamic situations encountered in daily life. Immersive virtual reality simulations can be used to simulate dynamic and interactive situations in a controlled setting. Adding eye tracking to such simulations may provide highly detailed outcome measures, and has great potential for neuropsychological assessment. Here, participants (83 stroke patients and 103 healthy controls) we instructed to find either 3 or 7 items from a shopping list in a virtual super market environment while eye movements were being recorded. Using Logistic Regression and Support Vector Machine models, we aimed to predict the task of the participant and whether they belonged to the stroke or the control group. With a limited number of eye movement features, our models achieved an average Area Under the Curve (AUC) of .76 in predicting whether each participant was assigned a short or long shopping list (3 or 7 items). Identifying participant as either stroke patients and controls led to an AUC of .64. In both classification tasks, the frequency with which aisles were revisited was the most dissociating feature. As such, eye movement data obtained from a virtual reality simulation contain a rich set of signatures for detecting cognitive deficits, opening the door to potential clinical applications.

Indexes for the E-Baking Tray Task: A Look on Laterality, Verticality and Quality of Exploration

The Baking Tray Task is an ecological task developed for the assessment of unilateral neglect that can also be used for research on neurotypical participants. In this task, participants are asked to place 16 objects inside a board as evenly as possible. In the case of impaired spatial exploration, consequent to right attentional networks damage, asymmetrical object disposition is observed as more objects are placed on the ipsilesional side (typically the right side). The E-BTT is a technology-enhanced version of the Baking Tray Task, implemented with a software platform, E-TAN, which detects the objects and automatically computes their spatial coordinates. This allows a complement to the traditional scoring methods with new measures to extract richer information from the data. In this study, we focus on neurotypical participants to explore if some new indexes, derived from the literature review on similar tasks, can be applied to BTT and E-BTT for research aims. A principal component analysis (PCA) was then performed to verify if these new indexes reflect some common dimensions. Results indicate the emergence of two principal dimensions: spatiality, which summarizes both laterality and verticality, and quality, which regards the explored space and (dis)organization in placing the items.

Links between organized visual search and reading ability in French primary school children

Visual search skills develop substantially during the primary school years, and in parallel with children's reading achievement. Reading requires an efficient visual search and exposure to reading from the left to the right could also influence the way we explore space. No study, however, made links between visual search strategies and reading ability. In this study, 70 primary school children performed a cancellation task (Bells test) and reading tests. Our results showed that reading was closely linked to visual search accuracy but also to visual search organization, even after controlling for age for some measures. Along with the development of reading abilities, children made fewer revisitation, moved more to the nearest unmarked targets than to the farthest ones and explored more in lines. It appears, therefore, essential to take more into account the visual search organization of children with reading impairments such as dyslexia.

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.

Ignoring space around a painful limb? No evidence for a body-related visuospatial attention bias in complex regional pain syndrome

BACKGROUND

Complex Regional Pain Syndrome (CRPS) is a disorder of severe chronic pain in one or more limb(s). People with CRPS report unusual perceptions of the painful limb suggesting altered body representations, as well as difficulty attending to their affected limb (i.e., a 'neglect-like' attention bias). Altered body representations and attention in CRPS might be related, however, existing evidence is unclear. We hypothesized that if there were a body-related visuospatial attention bias in CRPS, then any attention bias away from the affected side should be larger for or limited to circumstances when the (impaired) body representation is involved in the task versus when this is not the case.

METHODS

We included 40 people with CRPS, 40 with other limb pain conditions, and 40 pain-free controls. In half of the people with pain, their upper limb was affected, in the other half their lower limb. We administered computerized tasks of spatial attention, including free viewing of images, shape cancellation, temporal order judgement, and dot-probe. The degree to which different versions of each task involved body representation was manipulated by one or more of the following: (1) presenting stimuli nearer versus further away from the body, (2) using body related versus neutral stimuli, and (3) inducing mental rotation of body parts versus no mental rotation. In addition to perceptual judgements, eye movements were recorded as a sensitive index of spatial attention. Bayesian repeated measures analyses were performed.

RESULTS

We found no evidence for a (body-related) visuospatial attention bias in upper limb CRPS. Secondary analyses suggested the presence of a body-related visuospatial attention bias away from the affected side in some participants with lower limb CRPS.

DISCUSSION

Our results add to growing evidence that there might be no general visuospatial attention bias away from the affected side in CRPS.

Visual search strategies in children: A reflection of working memory processes?

Visual search is not only less accurate but also less organized in children than in adults. However, visual search strategies in children have not been extensively studied and they are not evaluated in clinical practice. Working memory could play a critical role for the execution and the maintaining of a visual search strategy. Few studies if any have explored the links between visual search organization and working memory in children. In the present study, 54 primary school children performed a cancellation task (Bells test) and working memory tests (span tasks). Our results suggested that, contrary to visual search accuracy, visual search organization was significantly linked to working memory and, more specifically, to the efficiency of the central executive component. There is, thus, a real need to better understand the visual search process and to improve its assessment with cancellation tests in clinical practice.

Moving foraging into three dimensions: Feature- versus conjunction-based foraging in virtual reality

Visual attention evolved in a three-dimensional (3D) world, yet studies on human attention in three dimensions are sparse. Here we present findings from a human foraging study in immersive 3D virtual reality. We used a foraging task introduced in Kristjánsson et al. to examine how well their findings generalise to more naturalistic settings. The second goal was to examine what effect the motion of targets and distractors has on inter-target times (ITTs), run patterns, and foraging organisation. Observers foraged for 50 targets among 50 distractors in four different conditions. Targets were distinguished from distractors by either a single feature (feature foraging) or a conjunction of features (conjunction foraging). Furthermore, those conditions were performed both with static and moving targets and distractors. Our results replicate previous foraging studies in many aspects, with constant ITTs during a "cruise-phase" within foraging trials and response time peaks at the end of foraging trials. Some key differences emerged, however, such as more frequent switches between target types during conjunction foraging than previously seen and a lack of clear mid-peaks during conjunction foraging, possibly reflecting that differences between feature and conjunction processing are smaller within 3D environments. Observers initiated their foraging in the bottom part of the visual field and motion did not have much of an effect on selection times between different targets (ITTs) or run behaviour patterns except for the end-peaks. Our results cast new light upon visual attention in 3D environments and highlight how 3D virtual reality studies can provide important extensions to two-dimensional studies of visual attention.

The relationship between visuospatial neglect, spatial working memory and search behavior

Visuospatial neglect (VSN) is characterized by a lateralized attentional deficit in the visual domain. In addition, patients with VSN might have an impairment in the temporary storage of spatial information in working memory (spatial working memory; SWM) that, like VSN, could impair systematic searching behavior. Several studies have demonstrated either SWM impairments or impaired searching behavior in VSN patients. Here, we related SWM performance to search behavior in patients with and without VSN. We assessed SWM using a novel task in a group of 182 stroke patients (24 with VSN, 158 without) and 65 healthy controls. We related SWM performance to available stroke-related and cognitive data. Patients with VSN exhibited lower SWM performance than patients without VSN and healthy controls. Additional control analyses indicated that differences in SWM performance are specific to visuospatial processing, instead of e.g. verbal working memory or the general level of physical disability. Last, we related SWM performance to visual search performance on cancellation tasks, one where their cancellation markings remained visible and another one where their prior cancellations markings were invisible to the patient and therefore patients had to remember which targets they had canceled. SWM performance correlated with search organization. Together, these results from a large sample of stroke patients corroborate the findings of earlier studies, while excluding several alternative explanations: SWM impairment is a part of the neglect syndrome, and SWM impairments are related to search behavior.

Effects of a school-based sports program on psychosocial health and attention in youth with physical disabilities

PURPOSE

Youth with physical disabilities have lower psychosocial health and attention compared to their typically developing peers. Recent research has shown positive associations between sports participation and these outcomes. The purpose of the current study was to explore whether a school-based sports program affects psychosocial health and attention in youth with physical disabilities.

METHODS

Seventy children and adolescents (mean age (SD) 13.8 (2.9) years, aged 8-19 years, 54% boys) with physical disabilities were included in this quasi-experimental study from schools for special education. The sports group (n= 31) followed a school-based sports program (45 min/week) for six months. The control group followed the regular curriculum. Psychosocial health was assessed with self-perception (Self-Perception Profile for Children) and quality of life (DISABKIDS Chronic Generic Measure, DCGM-37). Attention was measured with experimental tasks on search efficiency, sustained attention, and distractibility.

RESULTS

Linear regression analyses revealed no differences between the sports and control group for self-perception, quality of life, and attention.

CONCLUSION

A school-based sports program seems to have no effect on psychosocial health and attention in youth with physical disabilities. Research into the important factors influencing these variables is needed before further resources can be given to improve sports participation for increasing psychosocial health and attention.

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

Accurate tests of cognition are vital in (neuro)psychology. Cancellation tasks are popular tests of attention and executive function, in which participants find and 'cancel' targets among distractors. Despite extensive use in neurological patients, it remains unclear whether demographic variables (that vary among patients) affect cancellation performance. Here, we describe performance in 523 healthy participants of a web-based cancellation task. Age, sex, and level of education did not affect cancellation performance in this sample. We provide norm scores for indices of spatial bias, perseverations, revisits, processing speed, and search organisation. Furthermore, a cluster analysis identified four cognitive profiles among participants, characterised by many omissions (N=18), many revisits (N=18), relatively poor search organisation (N=125), and relatively good search organisation (N=362). Thus, patient scores pertaining to search organisation should be interpreted cautiously: Given the large proportion of healthy individuals with poor search organisation, disorganised search in patients might be pre-existing rather than disorder-related.

Visual search and autism symptoms: What young children search for and co-occurring ADHD matter

Superior visual search is one of the most common findings in the autism spectrum disorder (ASD) literature. Here, we ascertain how generalizable these findings are across task and participant characteristics, in light of recent replication failures. We tested 106 3-year-old children at familial risk for ASD, a sample that presents high ASD and ADHD symptoms, and 25 control participants, in three multi-target search conditions: easy exemplar search (look for cats amongst artefacts), difficult exemplar search (look for dogs amongst chairs/tables perceptually similar to dogs), and categorical search (look for animals amongst artefacts). Performance was related to dimensional measures of ASD and ADHD, in agreement with current research domain criteria (RDoC). We found that ASD symptom severity did not associate with enhanced performance in search, but did associate with poorer categorical search in particular, consistent with literature describing impairments in categorical knowledge in ASD. Furthermore, ASD and ADHD symptoms were both associated with more disorganized search paths across all conditions. Thus, ASD traits do not always convey an advantage in visual search; on the contrary, ASD traits may be associated with difficulties in search depending upon the nature of the stimuli (e.g., exemplar vs. categorical search) and the presence of co-occurring symptoms.

What Does It Take to Search Organized? The Cognitive Correlates of Search Organization During Cancellation After Stroke

OBJECTIVES

Stroke could lead to deficits in organization of visual search. Cancellation tests are frequently used in standard neuropsychological assessment and appear suitable to measure search organization. The current aim was to evaluate which cognitive functions are associated with cancellation organization measures after stroke.

METHODS

Stroke patients admitted to inpatient rehabilitation were included in this retrospective study. We performed exploratory factor analyses to explore cognitive domains. A digital shape cancellation test (SC) was administered, and measures of search organization (intersections rate and best r) were computed. The following cognitive functions were measured by neuropsychological testing: neglect (SC, line bisection; LB, Catherine Bergego Scale; CBS, and Balloons Test), visuospatial perception and construction (Rey Complex Figure Test, RCFT), psychomotor speed (Trail Making Test; TMT-A), executive functioning/working memory (TMT-B), spatial planning (Tower Test), rule learning (Brixton Test), short-term auditory memory (Digit Span Forward; DSF), and verbal working memory (Digit Span Backward; DSB).

RESULTS

In total, 439 stroke patients were included in our analyses. Four clusters were separated: "Executive functioning" (TMT-A, TMT-B, Brixton Test, and Tower Test), "Verbal memory" (DSF and DSB), "Search organization" (intersections rate and best r), and "Neglect" (CBS, RCFT copy, Balloons Test, SC, and LB).

CONCLUSIONS

Search organization during cancellation, as measured with intersections rate and best r, seems a distinct cognitive construct compared to existing cognitive domains that are tested during neuropsychological assessment. Administering cancellation tests and analyzing measures of search organization could provide useful additional insights into the visuospatial processes of stroke patients. (JINS, 2018, 24, 424-436).

CancellationTools: All-in-one software for administration and analysis of cancellation tasks

In a cancellation task, a participant is required to search for and cross out (“cancel”) targets, which are usually embedded among distractor stimuli. The number of cancelled targets and their location can be used to diagnose the neglect syndrome after stroke. In addition, the organization of search provides a potentially useful way to measure executive control over multitarget search. Although many useful cancellation measures have been introduced, most fail to make their way into research studies and clinical practice due to the practical difficulty of acquiring such parameters from traditional pen-and-paper measures. Here we present new, open-source software that is freely available to all. It allows researchers and clinicians to flexibly administer computerized cancellation tasks using stimuli of their choice, and to directly analyze the data in a convenient manner. The automated analysis suite provides output that includes almost all of the currently existing measures, as well as several new ones introduced here. All tasks can be performed using either a computer mouse or a touchscreen as an input device, and an online version of the task runtime is available for tablet devices. A summary of the results is produced in a single A4-sized PDF document, including high quality data visualizations. For research purposes, batch analysis of large datasets is possible. In sum, CancellationTools allows users to employ a flexible, computerized cancellation task, which provides extensive benefits and ease of use.

The right hemisphere is dominant in organization of visual search-A study in stroke patients

Cancellation tasks are widely used for diagnosis of lateralized attentional deficits in stroke patients. A disorganized fashion of target cancellation has been hypothesized to reflect disturbed spatial exploration. In the current study we aimed to examine which lesion locations result in disorganized visual search during cancellation tasks, in order to determine which brain areas are involved in search organization. A computerized shape cancellation task was administered in 78 stroke patients. As an index for search organization, the amount of intersections of paths between consecutive crossed targets was computed (i.e., intersections rate). This measure is known to accurately depict disorganized visual search in a stroke population. Ischemic lesions were delineated on CT or MRI images. Assumption-free voxel-based lesion-symptom mapping and region of interest-based analyses were used to determine the grey and white matter anatomical correlates of the intersections rate as a continuous measure. The right lateral occipital cortex, superior parietal lobule, postcentral gyrus, superior temporal gyrus, middle temporal gyrus, supramarginal gyrus, inferior longitudinal fasciculus, first branch of the superior longitudinal fasciculus (SLF I), and the inferior fronto-occipital fasciculus, were related to search organization. To conclude, a clear right hemispheric dominance for search organization was revealed. Further, the correlates of disorganized search overlap with regions that have previously been associated with conjunctive search and spatial working memory. This suggests that disorganized visual search is caused by disturbed spatial processes, rather than deficits in high level executive function or planning, which would be expected to be more related to frontal regions.

Reading direction shifts visuospatial attention: an Interactive Account of attentional biases

A growing amount of evidence confirms the influence of reading and writing habits on visuospatial processing, although this phenomenon has been so far testified mainly as a lateralized shift of a single behavioral sign (e.g., line bisection), with lack of proof from pure right-to-left readers. The present study contributed to this issue by analyzing multiple attentional and motor indexes in monolingual Italian (i.e., reading from left-to-right), and monolingual (i.e., reading from right-to-left) and bilingual Israeli (i.e., reading from right-to-left in Hebrew but also from left-to-right in English) participants' visuospatial performance. Subjects were administered a computerized standard star cancellation task and a modified version in which English letters and words were replaced by Hebrew ones. Tasks were presented on a graphics tablet, allowing recording of both chronometric and spatial parameters (i.e., measured in (x, y) vector coordinates). Results showed that reading direction modulated the on-line visuomotor performance (i.e., left-to-right vs. right-to-left shifts) from the beginning (i.e., first mark) to the end of the task (i.e., spatial distribution of omissions and subjective epicenter). Additionally, the spatial bias observed in a computerized line bisection task was also related to the participants' habitual reading direction. Overall, the results favor the proposal of an Interactive Account of visuospatial asymmetries, according to which both cultural factors, such as the directional scanning associated with language processing, and biological factors, such as hemispheric specialization, modulate visuospatial processing. Results are discussed in light of recent behavioral and neuroanatomical findings.

Visual neglect: is there a relationship between impaired spatial working memory and re-cancellation?

In visual search tasks, neglect patients tend to explore and repeatedly re-cancel stimuli on the ipsilesional side, as if they did not realize that they had previously examined the rightward locations favoured by their lateral bias. The aim of this study was to explore the hypothesis that a spatial working memory deficit explains these ipsilesional re-cancellation errors in neglect patients. For the first time, we evaluated spatial working memory and re-cancellation through separate and independent tasks in a group of patients with right hemisphere damage and a diagnosis of left neglect. Results showed impaired spatial working memory in neglect patients. Compared to the control group, neglect patients cancelled fewer targets and made more re-cancellations both on the left side and on the right side. The spatial working memory deficit appears to be related to re-cancellations, but only for some neglect patients. Alternative interpretations of re-exploration of space are discussed.

The development of organized visual search

Visual search plays an important role in guiding behavior. Children have more difficulty performing conjunction search tasks than adults. The present research evaluates whether developmental differences in children's ability to organize serial visual search (i.e., search organization skills) contribute to performance limitations in a typical conjunction search task. We evaluated 134 children between the ages of 2 and 17 on separate tasks measuring search for targets defined by a conjunction of features or by distinct features. Our results demonstrated that children organize their visual search better as they get older. As children's skills at organizing visual search improve they become more accurate at locating targets with conjunction of features amongst distractors, but not for targets with distinct features. Developmental limitations in children's abilities to organize their visual search of the environment are an important component of poor conjunction search in young children. In addition, our findings provide preliminary evidence that, like other visuospatial tasks, exposure to reading may influence children's spatial orientation to the visual environment when performing a visual search.

Spatial analysis after perinatal stroke: patterns of neglect and exploration in extra-personal space

This study was conducted to determine whether school-aged children who had experienced a perinatal stroke demonstrate evidence of persistent spatial neglect, and if such neglect was specific to the visual domain or was more generalized. Two studies were carried out. In the first, 38 children with either left hemisphere (LH) or right hemisphere (RH) damage and 50 age-matched controls were given visual cancellation tasks varying in two factors: target stimuli and stimulus array. In the second study, tactile neglect was evaluated in 41 children with LH or RH damage and 72 age-matched controls using a blindfolded manual exploration task. On the visual cancellation task, LH subjects omitted more target stimuli on the right, but also on the left, compared with controls. Children with RH lesions also produced a larger number of omissions on both the left and right sides than controls, but with poorer performance on the left. On the manual exploration task, LH children required significantly longer times to locate the target on both sides of the board than did controls. RH children had significantly prolonged search times on the left side, but not on the right, compared with controls. In both tasks, LH subjects employed unsystematic search strategies more often than both control and RH children. The search strategy of RH children also tended to be erratic when compared to controls, but only in the random arrays of the visual cancellation tasks; structure of the target stimuli improved their organization. These results demonstrate that children with early LH brain damage display bilateral difficulties in visual and tactile modalities; a pattern that is in contrast to that seen in adults with LH damage. This may result from disorganized search strategies or other subtle spatial or attentional deficits. Results of performance of RH children suggests the presence of contralateral neglect in both the visual and tactile modalities; a finding that is similar to the neglect in adult stroke patients with RH lesions. The fact that deficits in spatial attention and organizational strategies are present after very early focal damage to either the LH or the RH broadens our understanding of the differences in functional lateralization between the immature and mature brain. These results also add to evidence for limitations to plasticity in the developing brain. Our findings may have therapeutic and rehabilitative implications for the management of children with early focal brain lesions.

Spatio-temporal features of visual exploration in unilaterally brain-damaged subjects with or without neglect: results from a touchscreen test

Cognitive assessment in a clinical setting is generally made by pencil-and-paper tests, while computer-based tests enable the measurement and the extraction of additional performance indexes. Previous studies have demonstrated that in a research context exploration deficits occur also in patients without evidence of unilateral neglect at pencil-and-paper tests. The objective of this study is to apply a touchscreen-based cancellation test, feasible also in a clinical context, to large groups of control subjects and unilaterally brain-damaged patients, with and without unilateral spatial neglect (USN), in order to assess disturbances of the exploratory skills. A computerized cancellation test on a touchscreen interface was used for assessing the performance of 119 neurologically unimpaired control subjects and 193 patients with unilateral right or left hemispheric brain damage, either with or without USN. A set of performance indexes were defined including Latency, Proximity, Crossings and their spatial lateral gradients, and Preferred Search Direction. Classic outcome scores were computed as well. Results show statistically significant differences among groups (assumed p<0.05). Right-brain-damaged patients with USN were significantly slower (median latency per detected item was 1.18 s) and less efficient (about 13 search-path crossings) in the search than controls (median latency 0.64 s; about 3 crossings). Their preferred search direction (53.6% downward, 36.7% leftward) was different from the one in control patients (88.2% downward, 2.1% leftward). Right-brain-damaged patients without USN showed a significantly abnormal behavior (median latency 0.84 s, about 5 crossings, 83.3% downward and 9.1% leftward direction) situated half way between controls and right-brain-damaged patients with USN. Left-brain-damaged patients without USN were significantly slower and less efficient than controls (latency 1.19 s, about 7 crossings), preserving a normal preferred search direction (93.7% downward). Therefore, the proposed touchscreen-based assessment had evidenced disorders in spatial exploration also in patients without clinically diagnosed USN.

Pervasive cognitive impairment in acute rehabilitation inpatients without brain injury

OBJECTIVE

To establish feasibility for the hypothesis that patients in acute rehabilitation who are hospitalized for disorders not known to involve cerebral injury can have significant cognitive impairment.

DESIGN

A comparison of performances on neuropsychological tests between 2 samples of subjects: inpatients in an acute rehabilitation hospital without known cerebral disease and normal community-dwelling persons.

SETTING

Acute inpatient rehabilitation hospital.

PATIENTS AND PARTICIPANTS

Nineteen hospitalized patients without delirium who were screened for pre-existing cerebral and psychiatric illness, dementia, and dependency in basic self-care skills before hospitalization. Eighteen community-dwelling persons who were not different in terms of age and education served as the control group.

METHODS

Participants completed 10 commonly used neuropsychological tests of executive, language, and memory functions. Data were analyzed by using multivariate analysis of variance.

MAIN OUTCOME MEASUREMENTS

Raw scores on the 10 neuropsychological tests.

RESULTS

Hospitalized patients performed significantly worse on 9 of 10 tests than community-dwelling participants. Older hospitalized participants had significantly greater cognitive impairment than younger hospitalized participants, which suggested increased susceptibility to effects of hospitalization on cognition.

CONCLUSIONS

Patients hospitalized without brain injury, and especially elderly patients, should be carefully monitored for cognitive deficits that may affect posthospitalization quality of living. Further research is needed to determine whether the cognitive deficits in such patients persist after discharge and affect functional independence, and to identify mechanisms for the deficits. Furthermore, the use of hospitalized participants without brain injury as control subjects in neuropsychological studies of brain injury should be balanced with an additional comparison group of matched, neurologically healthy, normal subjects who live in the community to control for cognitive impairments that are associated with acute hospitalization.

Comparing consequences of right and left unilateral neglect in a stroke rehabilitation population

OBJECTIVE

This article details right and left unilateral neglect (UN) in a stroke rehabilitation population.

DESIGN

This prospective observational cohort study documented hemipersonal neglect and hemispatial neglect in 309 of 325 stroke rehabilitation patients consecutively admitted over a 28-month period. Shoulder-hand complications, safety concerns, length of stay, discharge function, and discharge destination were documented.

RESULTS

Of the 85 with right UN and 113 with left UN, 17.7% had expressive aphasia, and 17.7% had mixed or receptive aphasia. Hemispatial neglect was associated with hemianopsia (29.2% and 31.8% for right and left, respectively). Having both hemipersonal neglect and hemispatial neglect was related to greater safety risk (46.9% vs. 24.3%), greater incidence of shoulder-hand complications (28.3% vs. 9.9%), lower FIM scores (>10 points lower), longer length of stay (8 days), and less likelihood of discharge to home (67.3% vs. 87.4%) than subjects without UN. Results were similar for those with right and left UN.

CONCLUSIONS

Right and left UN occur after stroke, can be detected even in the presence of aphasia, and are associated with shoulder-hand problems, lower discharge function, and lower likelihood of discharge home. Having both hemispatial neglect and hemipersonal neglect impacts people more than having either type of UN alone.

Visualized representation of visual search patterns for a visuospatial attention test

Cancellation tests have been widely used in clinical practice and in research to evaluate visuospatial attention, visual scanning patterns, and neglect problems. The aim of the present work is to present a visualized interface for the visuospatial attentional assessment system that can be employed to monitor and analyze attention performance and the search strategies used during visuospatial processing of target cancellation. We introduce a pattern identification mechanism for visual search patterns and report our findings from examining the visual search performance and patterns. We also present a comparison of results across various cancellation tests and age groups. The present study demonstrates that our system can obtain more processing data about spatiotemporal features of visual search than can conventional tests.

Convergent validity of executive organization measures on cancellation

Cancellation tests have traditionally been used to measure visuospatial neglect. Recently, such tests have also been viewed as potential measures of executive function. Mark and colleagues (2004; Disorganized search on cancellation is not a consequence of neglect. Neurology, 63, 78-84) developed three objective measures of organization based on reconstructing target-marking pathways from one form of a cancellation test: mean inter-target distance, path intersection rate, and a quantification of overall path uniformity (i.e., predominantly radial versus horizontal cancellation progress) that they termed "best r". However, the validity of these measures with respect to a subjective judgment of organization was not assessed. In the present study, 50 observers rated the overall organization of 50 reconstructed pathways from stroke patients and non-brain-injured adults to allow evaluating the convergent validity of the three proposed executive organization measures. Inter-target distance (r = .86), intersection rate (r = .87), and best r (r = -.69) were all found to be highly correlated with observer ratings. These results indicate good convergent validity for all three executive organization measures on a form of the cancellation test.

Neglect assessment as an application of virtual reality

OBJECTIVE

In this study a cancellation task in a virtual environment was applied to describe the pattern of search and the kinematics of hand movements in eight patients with right hemisphere stroke.

METHODS

Four of these patients had visual neglect and four had recovered clinically from initial symptoms of neglect. The performance of the patients was compared with that of a control group consisting of eight subjects with no history of neurological deficits.

RESULTS

Patients with neglect as well as patients clinically recovered from neglect showed aberrant search performance in the virtual reality (VR) task, such as mixed search pattern, repeated target pressures and deviating hand movements. The results indicate that in patients with a right hemispheric stroke, this VR application can provide an additional tool for assessment that can identify small variations otherwise not detectable with standard paper-and-pencil tests.

CONCLUSION

VR technology seems to be well suited for the assessment of visually guided manual exploration in space.

Productive and Optic Prism Exposureproductive and Defective Impairments in the Neglect Syndrome: Graphic Perseveration, Drawing Productions and Optic Prism Exposure

The effects of adaptation to prisms displacing rightwards the field of vision on omission errors, and on perseveration and other graphic productions in a line cancellation task, were assessed in nine right-brain-damaged patients with left unilateral spatial neglect. Prism adaptation improved both neglect, as indexed by omission errors, and perseveration behaviour, up to a delay of 60 min. No correlation was found between omission and perseveration errors in all assessments. The suggestion is made that perseveration and other complex graphic productions made by right brain-damaged-patients with left spatial unilateral neglect is due to a defective monitoring of complex motor behaviour, frequently associated to cerebral damage involving the right frontal lobe. Interpretations of perseveration behaviour in terms of allochiria and directional hypokinesia are considered, and their limits discussed.