Letter Cancellation Task Research Articles

Visual Attention in Children With Normal Hearing, Children With Hearing Aids, and Children With Cochlear Implants

Previous studies have reported both positive and negative effects of deafness on visual attention. The purpose of this study was to replicate and expand findings of previous studies by examining visual attention abilities in children with deafness and children with normal hearing. Twenty-eight children, ages 8-14 years, were evaluated. There were two groups of children with prelingual deafness and one group with normal hearing. The children with deafness were divided further into two groups: those with cochlear implants and those with conventional hearing aids. Unlike previous studies, the current study found no substantial differences in performance among these three groups of children on a continuous-performance visual attention task or on a letter cancellation task. Children in all three groups performed very well on the visual attention tasks. Furthermore, there was little association between performance on the visual attention tasks and parent or teacher ratings of behavior and attention. Age and nonverbal intelligence were significantly correlated with performance on visual attention tasks. The theoretical implications of these findings are discussed, along with directions for future research.

Letter Cancellation Performance Across the Adult Life Span

Letter cancellation tasks are paper and pencil tests widely used in clinical and research settings as quick measures of attention/concentration, visual-spatial scanning abilities, and visual-spatial dysfunctions such as spatial neglect. Despite their popularity, only a few studies have investigated effects of age on letter cancellation performance and no comprehensive large-scale adult life-span norms are available for any of the letter cancellation tasks. We have developed a letter cancellation test, and we report a normative data obtained from a partially stratified sample of 351 healthy adults between 18 and 91 years of age. The results show the expected large age-related decline in the speed of letter cancellation performance and no age-related differences in spatial distribution of cancellation errors. We also provide various equations for precise predictions of Cancel H test performance. The results of correlational analyses show high reliability and provide evidence for both convergent and divergent validity of our letter cancellation task.

Early morning melatonin administration impairs psychomotor vigilance

The acute soporific effect of melatonin in humans has been demonstrated in a range of studies. How alertness and performance are changed after melatonin given in the morning is not yet known. In a double-blind, placebo-controlled study of nine healthy young men, melatonin was given at 0700 h under controlled conditions of a modified constant routine protocol lasting 56 h (2 days, 3 nights with sleep). A clear decrement in neurobehavioral functions as measured by the Psychomotor Vigilance Test lasted for 6 h after melatonin administration (particularly in the lapse domain and median of the reaction time) without any effect on a letter cancellation task. A subjective soporific effect was present but less pronounced. Thus, melatonin taken in the morning requires caution in situations where high attention is needed.

Voluntary Oculomotor Performance Upon Awakening After Total Sleep Deprivation

The potential impact of sleep inertia on measures of voluntary oculomotor control have been surprisingly neglected. The present study examined the effects of 40 hours of sleep deprivation on saccadic (SAC) and smooth pursuit (SP) performance, attentional/visual search performance (Letter Cancellation Task, LCT) and subjective sleepiness (Sleepiness Visual Analog Scale, SVAS) recorded immediately after awakening. Standard polysomnography of nine normal subjects was recorded for 3 nights (1 adaptation, AD; 1 baseline, BSL; 1 recovery, REC); BSL and REC were separated by a period of 40 h of continuous wakefulness, during which subjects were tested every two hours. Within 30 s of each morning awakening, a test battery (SAC, SP, LCT, SVAS) was administered to subjects in bed. For data analysis, mean performance obtained during the day preceding the sleep deprivation night was considered as "Diurnal Baseline" and compared to performance upon awakening from nocturnal sleep. As a consequence of sleep deprivation, SWS percentage was doubled during REC. Saccade latency increased and velocity decreased significantly upon awakening from REC as compared to the other three conditions (Diurnal baseline, AD awakening, BSL awakening); accuracy was unaffected. As regards SP, phase did not show any impairment upon awakening, while velocity gain upon awakening from REC was significantly lower as compared to the other conditions. Finally, number of hits on LCT upon awakening from REC was significantly lower and subjective sleepiness higher as compared to Diurnal Baseline. It is concluded that 40 h of sleep deprivation significantly impaired performance to SAC and SP tasks recorded upon awakening from recovery sleep. This performance worsening is limited to the measures of speed, while both SAC accuracy and SP phase do not show a significant decrease upon awakening. Since saccadic velocity has recently been found to negatively correlate with simulator vehicle crash rates, it is suggested that the adverse effects of sleep deprivation on sleep inertia magnitude should be avoided by any personnel who may have to perform critical tasks involving high oculomotor control immediately after awakening.

Effects of Stimulus Properties and Age on Random-Array Letter Cancellation Tasks

Random-array letter cancellation tasks are commonly used in the clinical assessment of visuospatial function. How stimulus properties and aging affect cancellation performance is not well understood. This study evaluated the effects of stimulus factors and age on 3 measures of cancellation performance. Thirty younger and 30 older adults each completed 12 cancellation forms that varied in paper size, stimulus density, and target-to-distractor (T/D) ratio. Interactions between stimulus factors were identified for a calculated composite measure of speed and accuracy (effectiveness), a standardized measure of the time required for completion of forms, and a standardized measure of the number of omission errors. The results showed complex interactions between stimulus factors that were different for each dependent variable. These interactions were generally similar for both age groups. The findings indicate that both stimulus properties and dependent variables must be carefully considered in the design and interpretation of cancellation paradigms.

Evaluation of cognitive and psychomotor effects of nisoldipine or placebo in healthy volunteers

The purpose of this study was to compare the cognitive and psychomotor effects of the calcium antagonist nisoldipine with placebo in healthy volunteers over the three-week period of this randomised, double-blind, parallel group trial. Thirty volunteers received either a twice-daily dose of 10 mg nisoldipine or placebo. Psychometric testing and measurement of blood pressure and heart rate were carried out on days 0, 7, 14 and 21. Psychometric testing included: Critical Flicker Fusion (CFF), Choice Reaction Time (CRT), Digit Span (DS), Digit Symbol Substitution Test (DSST), and Letter Cancellation (LC). No significant treatment effects were found. CFF performance improved for both groups during the first week. In the CRT task, significant improvements were observed on days 14 and 21, relative to baseline, for total and motor reaction time. Similar improvements over time were found on the LC and DSST tasks. There were no significant differences between the active treatment and placebo for heart rate and systolic/diastolic blood pressure and nisoldipine was well tolerated. The results of this study indicate that nisoldipine does not have any cognition enhancing properties but, unlike some calcium antagonists, it does not markedly impair CNS activity. Copyright 2000 John Wiley & Sons, Ltd.

Longitudinal study of cognitive function in first-episode and recent-onset schizophrenia.

Whether cognitive function in schizophrenia deteriorates, improves, or remains stable is a crucial question. Few studies have examined the longitudinal stability of cognitive function and the relationship between cognitive performance and clinical symptoms over time in a cohort of well-treated patients with schizophrenia. In the present study, 54 patients with first-episode and recent-onset schizophrenia completed a comprehensive cognitive test battery and were rated on symptom measures at index hospitalization and again after 5 years. Performance IQ and full-scale IQ significantly improved, whereas verbal IQ did not change. Group performance improved on some of the neuropsychological tests, including the Circle A letter-cancellation task, free recall of logical memory test score, and the Wisconsin Card Sorting Test. Mean finger-tapping performance worsened over time, whereas performance on other neuropsychological tests did not change. Negative, psychotic, and disorganized symptoms significantly improved over the time period. Changes in negative symptoms were correlated with performance changes in verbal IQ and full-scale IQ but not performance IQ. Improvement in verbal cognition was observed when negative symptoms improved. Psychotic and disorganized symptom dimensions were not correlated with any IQ measure. These results indicate that in a cohort of young patients receiving neuroleptic treatment early in their illness, cognitive performance does not deteriorate--and may improve. Only one of the three symptom dimensions--negative--was associated with change in cognitive performance. This study supports the view that negative symptoms are associated with a poor long-term cognitive outcome and may be closely related to the primary cognitive deficit in schizophrenia.

Representations of knowledge about dominoes in demented and normal elderly players

1. 1. Dementia patients who retain musical and game-playing skills exhibit impaired performance on explicit memory tests of knowledge about their retained skill. 2. 2. Dementia patients who retain skill at playing dominoes can answer complex questions about the play of the game almost as well as normal elderly domino players when the questions are presented with real dominoes. 3. 3. The aim of this study was to determine if skilled dementia patients could answer questions about domino play when the stimuli were two-dimensional drawings of dominoes. 4. 4. Seventeen dementia patients and eight normal elderly domino players were tested on two forms of the Domino Quiz: first with real dominoes, then with two-dimensional drawings; other neuropsychological tests were given at the same time. 5. 5. Fourteen of the 17 patients and all of the controls showed no decline in answering questions about domino play when two-dimensional drawings were used. These patients showed retained symbolic processing of information about dominoes despite declines in overall mental status, generation of words from specific semantic categories and recognition memory for domino terminology. 6. 6. Because the 14 patients with retained domino skill performed as accurately as controls on both administrations of a letter cancellation task, the ability to process familiar symbols may be important to their game-playing skill.

Spatial Aspects of Letter Cancellation Performance in Arabic Readers

Studies of visuospatial and directed attention that used subjects drawn from cultures with left-to-right reading patterns have suggested a slight performance bias toward left space. This pattern could reflect an intrinsic, organic, bias in spatial processing or the confounding effect of overlearned reading patterns. We studied the spatial distribution of errors on random array letter cancellation tasks obtained from 128 healthy Syrians who were native readers of Arabic. Fifty-eight of the 128 subjects (45.3%) made a total of 91 errors in which they omitted canceling a target. The distribution of errors was not spatially biased. This differs from the error pattern reported for native readers of English on a similar task. The findings, consistent with results of other approaches, suggest that reading patterns influence visuospatial attention, but are not the sole cause of spatial biases observed in readers of Indo-European languages.

Sleepiness, alertness and performance during a laboratory simulation of an acute shift of the wake-sleep cycle

Monitoring the presence of sleepiness on the job and its effects on performance is of primary importance for improving schedule systems of shiftworkers. Shiftworkers, often involved in night-time operations and irregular work schedules, frequently complain of nocturnal sleepiness especially in conditions of abrupt shift of the wakesleep cycle. In this study, the authors evaluated the effects of a laboratory simulation of acute night-shift changes on sleepiness, vigilance and performance, using Maintenance of Wakefulness Test,Multiple Sleep Latency Test and three pencil and paper tests: Digit Symbol Substitition Test, ‘Deux Barrages’ Test and a 3-Letter Cancellation Task. All of the tests were administered four times at 2-hourly intervals during the night after daytime sleep. Results showed that the ability to maintain wakefulness and to perform simple visuo-attentive tasks is substantially spared during the night. On the other hand, sleep tendency and performance on a more complex and monotonous task (Letter Cancellation Task) reveal, respectively, increasing sleepiness and degrading performance.

Stimulus Characteristics Determine Processing Approach on Random Array Letter-Cancellation Tasks

Target-to-distractor ratio strongly influences performance on typical random array letter cancellation tasks, suggesting that a “controlled” processing approach is used. This study was designed to determine whether “automatic” processing could be also demonstrated in the random array cancellation paradigm by changing the perceptual characteristics of the stimuli. Thirty-two healthy subjects sequentially performed four random array cancellation tasks with 50 and 100 stimuli. The letters “I” or “O'' were targets and “L” served as the distractor. Performance was measured by the number of correctly canceled targets divided by the time to completion, corrected for accuracy. There was a strong effect of the number of stimuli on forms using I targets (p< .00001), but not for O's (p= .15) Performance scores were lower for I target forms than for O targets. These findings demonstrate that performance approximating “automatic” processing can also be elicited on clinically useful, office-based, or bedside tests such as random array cancellation.

Visual Selective Attention and Reading Efficiency are Related in Children

We investigated the relationship between visual selective attention and linguistic performance. Subjects were classified in four categories according to their accuracy in a letter cancellation task involving selective attention. The task consisted in searching a target letter in a set of background letters and accuracy was measured as a function of set size. We found that children with the lowest performance in the cancellation task present a significantly slower reading rate and a higher number of reading visual errors than children with highest performance. Results also show that these groups of searchers present significant differences in a lexical search task whereas their performance did not differ in lexical decision and syllables control task. The relationship between letter search and reading, as well as the finding that poor readers-searchers perform poorly lexical search tasks also involving selective attention, suggest that the relationship between letter search and reading difficulty may reflect a deficit in a visual selective attention mechanisms which is involved in all these tasks. A deficit in visual attention can be linked to the problems that disabled readers present in the function of magnocellular stream which culminates in posterior parietal cortex, an area which plays an important role in guiding visual attention.

Assessing vigilance through a brief pencil and paper letter cancellation task (LCT): effects of one night of sleep deprivation and of the time of day

Behavioural effects of the lack of sleep in normal subjects have been investigated mostly by experimenter-paced choice reaction times in prolonged stimulus detection tasks. However, length and procedure complexity of these tasks limit their use in research on larger numbers of subjects. The aim of the present study was to assess the effectiveness of a brief subject-paced pencil and paper performance task, i.e. letter cancellation task (LCT) in revealing the effects of one night of sleep deprivation. In addition, the authors evaluated sleep loss and time of day effects on six Visual Analogue Scales (VAS) measuring subjective activation-deactivation. Results show that a LCT is sensitive in revealing the effects of time of day and of 24 h of sleep deprivation. Effects of sleep deprivation were also revealed by VAS data. Sleepiness, tiredness and energy scales on the VAS were also affected by time of day. Despite the sensitivity of both the LCT and VAS, there was little correspondence between performance and subjective measures.

Effect of stimulus number, target-to-distractor ratio, and motor speed on visual spatial search quality following traumatic brain injury

The object of this study was to investigate stimulus effects and motor limitations on visuospatial performance after traumatic brain injury TBI. Previous findings have not fully explained the basis of attentional impairments after TBI. There has been little study of the spatial aspects of attention and information processing in this group. We studied 20 patients after severe TBI and 21 healthy controls. Four random-array letter cancellation tasks, varying in number of stimuli 50 and 100 and target-todistractor ratio 1 : 4 and 1 : 9 were employed. Performance was calculated from the number and proportion of cancelled targets, as well as time to completion. TBI subjects were slower on finger tapping and achieved lower cancellation perfomance scores. Both TBI subjects and controls performed better on tasks with target-to-distractor T D ratios of 1 : 4 than on those with 1 : 9. There was no effect of stimulus number. We conclude that there are both quantitative speed and qualitative contributors to impaired visuospatial ability following TBI. Motor impairments may slow the overall cancellation performance, but the differential effect of T D ratio in the two populations suggests that TBI impairs quality of research. Accounting for both speed and accuracy suggests increased utility for the cancellation paradigm in clinical and research assessment of visuospatial attention.

Effects of Stimulus Number and Target-to-Distractor Ratio on the Performance of Random Array Letter Cancellation Tasks

Cancellation tests are commonly used in the clinical assessment of visuospatial function, but there has been little study of task characteristics influencing performance. This study was designed to assess factors which affect cancellation performance. Sixteen healthy subjects sequentially performed four random-array letter cancellation tasks. The forms contained 50 and 100 stimuli and target:distractor (T/D) ratios of 1:4 and 1:9 with target letter “A” and randomly selected letter distractors. The primary performance measure was calculated as the number of correctly cancelled targets divided by the time to complete the task, corrected for accuracy. This measure revealed a strong effect of T/D ratio (p< .0001), with performance adversely affected by higher proportion of distractors. There was no effect of stimulus number. This suggests that T/D ratio should be considered in cancellation test design and interpretation.

Cigarette Smoking and Abstinence: Comparative Effects Upon Cognitive Task Performance and Mood State over 24 Hours

Twenty regular smokers were assessed over 24-h of normal cigarette smoking, and an equivalent period of abstinence. In both conditions, a non-deprived baseline was followed by performance tests 2, 6 and 24 h later, while subjective feelings were assessed every 2 h. Compared to normal smoking, abstinence led to reduced heart rate, worse task performance, feelings of depression, stress, irritability, restlessness, poor concentration, and urges to smoke. Letter cancellation and number vigilance task performance were significantly poorer after 2 and 6 h of abstinence. Subjective feeling states were significantly worse after 4 h of abstinence, and became increasingly impaired over the rest of the day. However many abstinence symptoms (except heart rate), were reduced in severity at the 24-h session, held on the morning of the following day. This suggests that many of the psychological effects of smoking abstinence, may build-up afresh each day.

Peripartal cognitive impairment: Secondary to depression?

Twenty pregnant women and 20 controls matched for age and IQ were tested on a range of cognitive functions at three time points: in the last month of pregnancy, 48 hours after delivery, and four weeks after delivery. Pregnant women obtained significantly lower scores on digit symbol and paced auditory serial addition tests 48 hours after delivery. There were no significant differences between the groups on logical memory, trail making or letter cancellation tasks. The degree of cognitive impairment was correlated with the severity of depression, and the differences between the pregnant and control groups in cognitive function became nonsignificant when the effect of depression was controlled. Cognitive functions related to fluid cognitive ability are impaired in the immediate post‐partum period and the severity of impairment is correlated with self‐reported depression.

Attention deficits in adolescents with ADHD and other clinical groups

Abstract Adolescents with a childhood diagnosis of ADHD were compared to adolescents with other psychiatric disorders and to a control group on aspects of attentional functioning. IQ was covaried in the analyses. The ADHD group performed significantly more poorly than did comparison groups except on the Stroop test, where all clinical groups showed reduced resistance to interference. On the Paced Auditory Serial Addition Test and the Letter Cancellation Task the adolescents with ADHD were markedly poorer and could not develop appropriate strategies to cope with the task demands. It is argued that the concept of the Supervisory Attentional System (SAS; Shallice, 1991) has heuristic value in understanding the persisting attentional problems of individuals with ADHD.

Gross motor activity and attention in three adults with brain injury.

In this single-subject study, we evaluated the short-term effects of gross motor activity on the attention behavior of three adults with brain injury. Additionally, observation data were collected on each subject's performance. The effects of gross motor activity on the subjects' attention behavior was measured by performance on visual letter cancellation tasks. The three subjects with brain injury were a 59-year-old woman, a 52-year-old man, and a 26-year-old woman. Data for each subject were graphed and visually analyzed. Observation data for each subject also were examined. The results did not indicate meaningful differences in the subjects' performance of letter cancellation tasks after gross motor activity. However, positive changes in scanning and checking behaviors were noted. This study did not demonstrate improvement in attention behavior after gross motor activity according to the measures used. However, the study supports that observations can help to identify important factors that may influence treatment outcomes. Further study is needed to determine the nature of the relationship between gross motor activity and attention.

Ethanol‐Induced CNS depression and divided attention

AbstractSubject performed a divided attention task in which they detected occurrences of a target letter in a stimulus figure which was a large letter made up of an array of small letters. Subjects pressed one button if the large letter was the target, another if the small letters were the target.Performance on this task was compared to other attention and psychomotor tasks in a three‐way randomized crossover study comparing two doses of alcohol with placebo in 12 healthy volunteers (six male, six female, aged 19–41). The higher dose of alcohol produced blood concentrations of 43 mg/100 ml, the lower dose 16 mg/100 ml.Subjects reported themselves significantly more drunk on both doses of alcohol than on placebo, showed poorer long‐term recall on the Buschke selective reminding task than on placebo, and made more errors on a letter cancellation task. They performed letter cancellation faster, however. No significant effects were seen on the divided attention or continuous attention tasks, though continuous attention showed a trend towards impairment.These results suggest that the greater sensitivity showed by some multiple task combinations to low doses of drugs such as alcohol is not due to divided attention as such, but results from some aspect of task combination. The coupling of increased errors but increased speed on letter cancellation has obvious implications for the interpretation of the effects of alcohol on complex real‐life tasks such as driving.