Purpose
The Single Letter Cancellation Test (SLCT) is used to evaluate the presence and severity of visual scanning deficits, and is used to evaluate unilateral spatial neglect (USN) in the near extra personal space (Diller, Ben-Yishay, Gertsman, Goodkin, Gordon, & Weinberg, 1974).
In-Depth Review
Purpose of the measure
The Single Letter Cancellation Test (SLCT) is used to evaluate the presence and severity of visual scanningDuring this intervention the person with USN is encouraged to conduct voluntary eye movements toward the neglected visual field (usually the left side) by performing a task in that hemispace. The treatment often includes a visual target that the patient uses as an anchor to direct voluntary gaze control while scanning.
deficits, and is used to evaluate unilateral spatial neglect (USN) in the near extra personal space (Diller, Ben-Yishay, Gertsman, Goodkin, Gordon, & Weinberg, 1974).
Available versions
The SLCT was published by Diller et al. in 1974.
Features of the measure
Items:
There are no actual items for the SLCT.
The test consists of one 8.5 x 11 sheet of paper containing 6 lines with 52 letters per line. The stimulus letter H is presented 104 times. The page is placed at the patient’s midline. The patient is told to put a line through each H that is found on the page. The time taken to complete the test is recorded.
Scoring:
The score is calculated by subtracting the number of omissions (H’s that were not crossed out) from the possible perfect score of 104 (0 to 53 on the left and 0 to 51 on the right). Higher scores indicate better performance. Presence of USN can be inferred by calculating the frequency of errors to the left or to the right from the center of the page. Omissions of 4 or more have been found to be pathological (Zoccolotti, Antonucci, Judica, Montenero, Pizzamiglio, & Razzano, 1989). Commissions are rarely seen and are therefore not included in the analyses.
Normative data has been published by sex and age, based on the results from 341 patients with lesions of the right hemisphere (Gordon, Ruckdeschel-Hibbard, Egelko, Diller, Simmens, & Langer, 1984).
Normative data has been published by sex and age, based on the results from 341 patients with lesions of the right hemisphere (Gordon, Ruckdeschel-Hibbard, Egelko, Diller, Simmens, & Langer, 1984).
Time:
Less than 5 minutes.
Training:
None typically reported.
Subscales:
None.
Equipment:
- 11x 8-inch page of paper containing 6 lines with 52 letters per line and the stimulus letter H presented 104 times (53 times on left, 51 on right).
- Pencil
- Stopwatch
Alternative forms of the SLCT
None typically reported.
Client suitability
Can be used with: Patients with strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain..
- Patients must be able to hold a pencil to complete the test (the presence of apraxia may impair this ability).
- Patients must be able to recognize letters of the alphabet to complete the test.
Should not be used with:
- The SLCT cannot be used to differentiate between sensory neglect and motor neglect because it requires both visual search and manual exploration (Ladavas, 1994).
- The SLCT cannot be completed by proxy.
In what languages is the measure available?
The SLCT has been used with English and French-speak patients.
A Hebrew version of the SLCT has been used in some studies as part of the Behavioral Inattention Test (e.g. Friedman & Nachman-Katz, 2004).
Summary
| What does the tool measure? |
Unilateral Spatial Neglect (USN) in the near extra personal space. |
| What types of clients can the tool be used for? |
Patients with strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain.. |
Is this a screeningTesting for disease in people without symptoms.
or assessment tool? |
ScreeningTesting for disease in people without symptoms.
. |
| Time to administer |
Less than 5 minutes. |
| Versions |
None. |
| Other Languages |
The SLCT has been used with English and French-speak patients. A Hebrew version of the SLCT has been used in some studies as part of the Behavioral Inattention Test.
|
| Measurement Properties |
ReliabilityReliability can be defined in a variety of ways. It is generally understood to be the extent to which a measure is stable or consistent and produces similar results when administered repeatedly. A more technical definition of reliability is that it is the proportion of "true" variation in scores derived from a particular measure. The total variation in any given score may be thought of as consisting of true variation (the variation of interest) and error variation (which includes random error as well as systematic error). True variation is that variation which actually reflects differences in the construct under study, e.g., the actual severity of neurological impairment. Random error refers to "noise" in the scores due to chance factors, e.g., a loud noise distracts a patient thus affecting his performance, which, in turn, affects the score. Systematic error refers to bias that influences scores in a specific direction in a fairly consistent way, e.g., one neurologist in a group tends to rate all patients as being more disabled than do other neurologists in the group. There are many variations on the measurement of reliability including alternate-forms, internal consistency , inter-rater agreement , intra-rater agreement , and test-retest .
|
Internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency.:
No studies have examined the internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency. of the SLCT.
Test-retest:
One study has examined the test-retest reliabilityA way of estimating the reliability of a scale in which individuals are administered the same scale on two different occasions and then the two scores are assessed for consistency. This method of evaluating reliability is appropriate only if the phenomenon that the scale measures is known to be stable over the interval between assessments. If the phenomenon being measured fluctuates substantially over time, then the test-retest paradigm may significantly underestimate reliability. In using test-retest reliability, the investigator needs to take into account the possibility of practice effects, which can artificially inflate the estimate of reliability (National Multiple Sclerosis Society).
of the SLCT and reported adequate test-retest. |
ValidityThe degree to which an assessment measures what it is supposed to measure.
|
Construct:
Adequate correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases - for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases - for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation.
with mean CT-scan damage; adequate to excellent correlations with Albert’s Test , Sentence Reading Test, and the Wundt-Jastrow Area Illusion Test; significant correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases - for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases - for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation.
with the Semi-Structured Scale for the Functional Evaluation of Hemi-inattention. |
| Does the tool detect change in patients? |
Not applicable. |
| Acceptability |
The SLCT should be used as a screeningTesting for disease in people without symptoms.
tool rather than for clinical diagnosis of USN. Apraxia must be ruled out as this may affect the validityThe degree to which an assessment measures what it is supposed to measure.
of test results. This test cannot be completed by proxy. Patients must be able to hold a pencil and recognize letters of the alphabet to complete. The SLCT cannot be used to differentiate between sensory neglect and motor neglect. |
| Feasibility |
The SLCT requires no specialized training to administer and only minimal equipment is required (a pencil, a stopwatch, and the test paper). The test is simple to score and interpret. A suggested cutoff score for the presence of USN is provided (omissions of 4 or more). The test is placed at the patient’s midline and the time it takes for the patient to complete the test is recorded. |
| How to obtain the tool? |
Please click here to see a copy of the SLCT.
|
Psychometric Properties
Overview
In general, cancellation tests are believed to have greater test-retest reliabilityA way of estimating the reliability of a scale in which individuals are administered the same scale on two different occasions and then the two scores are assessed for consistency. This method of evaluating reliability is appropriate only if the phenomenon that the scale measures is known to be stable over the interval between assessments. If the phenomenon being measured fluctuates substantially over time, then the test-retest paradigm may significantly underestimate reliability. In using test-retest reliability, the investigator needs to take into account the possibility of practice effects, which can artificially inflate the estimate of reliability (National Multiple Sclerosis Society).
than line bisection tests and are often more sensitive for detecting USN than line bisection tests (Marsh & Kersel, 1993; Azouvi et al., 2002). The SLCT has been reported to have strong psychometric properties, including reliabilityReliability can be defined in a variety of ways. It is generally understood to be the extent to which a measure is stable or consistent and produces similar results when administered repeatedly. A more technical definition of reliability is that it is the proportion of "true" variation in scores derived from a particular measure. The total variation in any given score may be thought of as consisting of true variation (the variation of interest) and error variation (which includes random error as well as systematic error). True variation is that variation which actually reflects differences in the construct under study, e.g., the actual severity of neurological impairment. Random error refers to "noise" in the scores due to chance factors, e.g., a loud noise distracts a patient thus affecting his performance, which, in turn, affects the score. Systematic error refers to bias that influences scores in a specific direction in a fairly consistent way, e.g., one neurologist in a group tends to rate all patients as being more disabled than do other neurologists in the group. There are many variations on the measurement of reliability including alternate-forms, internal consistency , inter-rater agreement , intra-rater agreement , and test-retest .
and validityThe degree to which an assessment measures what it is supposed to measure.
, in identifying USN in the near extra personal space (Menon & Korner-Bitensky, 2004). For the purposes of this review, we conducted a literature search to identify all relevant publications on the psychometric properties of SLCT.
Reliability
Internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency.:
No evidence.
Test-retest:
Gordon, Ruckdeschel-Hibbard, Egelko, Diller, Simmens, and Langer (1984) examined the test-retest reliabilityA way of estimating the reliability of a scale in which individuals are administered the same scale on two different occasions and then the two scores are assessed for consistency. This method of evaluating reliability is appropriate only if the phenomenon that the scale measures is known to be stable over the interval between assessments. If the phenomenon being measured fluctuates substantially over time, then the test-retest paradigm may significantly underestimate reliability. In using test-retest reliability, the investigator needs to take into account the possibility of practice effects, which can artificially inflate the estimate of reliability (National Multiple Sclerosis Society).
of the SLCT using a group of 31 subjects and found adequate test-retest (r = 0.63).
Validity
Construct:
Egelko et al. (1988) found that the SLCT correlated adequately with mean CT-scan damage (r = -0.35).
Note: This correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases - for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases - for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation.
is negative because a high score on the SLCT indicates better performance, whereas a high CT-scan score indicates more damage.
Zoccolotti, Antonucci, Judica, Montenero, Pizzamiglio, and Razzano (1989) found that correlations between the SLCT and other visuo-spatial tests (Albert’s Test , Sentence Reading Test, and the Wundt-Jastrow Area Illusion Test) ranged from adequate to excellent (ranging from r = 0.36 to r = 0.69). The SLCT was found to be the most sensitive among these tests in detecting USN (from 4.1% to 25%), which may be due to the high density of stimuli used.
Zoccolotti, Antonucci, and Judica (1992) found that the SLCT correlated with the Extra personal subscaleMany measurement instruments are multidimensional and are designed to measure more than one construct or more than one domain of a single construct. In such instances subscales can be constructed in which the various items from a scale are grouped into subscales. Although a subscale could consist of a single item, in most cases subscales consist of multiple individual items that have been combined into a composite score (National Multiple Sclerosis Society).
of Semi-Structured Scale for the Functional Evaluation of Hemi-inattention (Kendal’s tau = -0.52).
Note: This correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases - for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases - for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation.
is negative because a high score on the SLCT indicates better performance, whereas a high score on the Semi-Structured Scale indicates the presence of USN.
Criterion:
No evidence.
Responsiveness
No evidence.
References
- Azouvi, P., Samuel, C., Louis-Dreyfus, A., et al. (2002). Sensitivity of clinical and behavioural tests of spatial neglect after right hemisphere stroke. J Neurol Neurosurg Psychiatry, 73, 160 -166.
- Diller, L., Ben-Yishay, Y., Gerstman, L. J., Goodin, R., Gordon, W., Weinberg, J. (1974). Studies in scanning behavior in hemiplegia. Rehabilitation Monograph No. 50, Studies in cognition and rehabilitation in hemiplegia. New York: New York University Medical Center, Institute of Rehabilitation Medicine.
- Egelko, S., Gordon, W. A., Hibbard, M. R., Diller, L., Lieberman, A., Holliday, R., Ragnarsson, K., Shaver, M. S., Orazem, J. (1988). Relationship among CT scans, neurological exam, and neuropsychological test performance in right-brain-damaged stroke patients. J Clin Exp Neuropsychol, 10, 539-564.
- Friedman, N., Nachman-Katz, I. (2004). Developmental neglect dyslexia in a hebrew-reading child. Cortex, 40(2), 301-313.
- Gordon, W.A., Ruckdeschel-Hibbard, M., Egelko, S., Diller, L., Simmens, S., Langer, K. (1984). Single Letter Cancellation Test in Evaluation of the Deficits Associated with Right Brain Damage: Normative Data on the Institute of Rehabilitation Medicine Test Battery. New York: New York University Medical Center.
- Ladavas, E. (1994). The role of visual attention in neglect: A dissociation between perceptual and directional motor neglect. Neuropsychological Rehabilitation, 4, 155-159.
- Marsh, N. V., Kersel, D. A. (1993). Screening tests for visual neglect following stroke. Neuropsychological Rehabilitation, 3, 245-257.
- Menon, A., Korner-Bitensky, N. (2004). Evaluating unilateral spatial neglect post stroke: Working your way through the maze of assessment choices. Topics in Stroke Rehabilitation, 11(3), 41-66.
- Zoccolotti, P., Antonucci, G., Judica, A., Montenero, P., Pizzamiglio, L., Razzano, C. (1989). Incidence and evoluation of the hemi-negelct disorder in chronic patients with unilateral right brain damage. Int J Neurosci, 47, 209-216.
See the measure
How to obtain the Single Letter Cancellation Test?
Please click here to see a copy of the SLCT.
