Double Letter Cancellation Test (DLCT)

Evidence Reviewed as of before: 19-08-2008
Author(s): Lisa Zeltzer, MSc OT; Anita Menon, MSc
Editor(s): Nicol Korner-Bitensky, PhD OT; Elissa Sitcoff, BA BSc

Purpose

The Double Letter Cancellation Test (DLCT) is used to evaluate the presence and severity of visual scanning deficits, and is used to evaluate unilateral spatial neglect (USN) in the near extrapersonal space (Diller, Ben-Yishay, Gertsman, Goodkin, Gordon, & Weinberg, 1974).

In-Depth Review

Purpose of the measure

The Double Letter Cancellation Test (DLCT) is used to evaluate the presence and severity of visual scanning deficits, and is used to evaluate unilateral spatial neglect (USN) in the near extrapersonal space (Diller, Ben-Yishay, Gertsman, Goodkin, Gordon, & Weinberg, 1974).

Available versions

The DLCT was published by Diller et al. in 1974.

Features of the measure

Items:

There are no actual items for the DLCT.

The patient is asked to look at an 8.5″x11″ sheet of paper containing 6 lines with 52 letters per line. Together, the stimuli letters C and E are presented 105 times. The patient is instructed to put a mark through all the letters C and E. The time taken to complete the test is recorded.

This test may be more challenging than cancellation of shapes or colours, since it requires the discrimination of 2 letters (C and E) from the rows of letters. The letters are arranged in structured rows and thus require less organizational skills than when the forms are randomly scattered on the page. This enables the therapist to examine more closely the issue of attention without the confounding factor of visual organization.

To begin the DLCT, the therapist places the test sheet at the patient’s midline and secures it with tape, and points to the trial line, asking the patient to mark the Cs and Es. If the patient is unable to perform the trial, further instruction is given. If the trial is correctly performed, the therapist will then proceed to give instructions as follows: “Look at the letters on this page. Put one line through each C and E. Ready, begin here”. The therapist points to the first letter in the first row and begins timing the patient.

Scoring:

The score is calculated by subtracting the number of omissions (Cs and Es that were not crossed out) from the possible perfect score of 105. Higher scores indicate better performance. The timing and total number of errors should be noted. According to Diller et al. (1974) 13 control subjects had a median error of 1 with a performance time of 100 seconds. Errors on the right with those on the left side of the page should be compared. Randomly scattered errors indicate poor sustained attention. Errors concentrated on one half of the page (either left or right) indicate USN. Commissions are rarely seen and are therefore not included in the analyses.

The patient’s general approach to the task should be observed (i.e. does the patient work from left to right or move randomly over the page; is their response time slowed; does the patient selectively choose the correct response or frequently mark non-target letters).

Normative data has been published by sex and age, based on the results from 241 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 8.5-inch page of paper containing 6 lines with 52 letters per line and the stimulus letters C and E presented 105 times.
  • Pencil
  • Stopwatch

Alternative Forms of the DLCT

  • Number version of the DLCT (Wade, Wood, & Hewer, 1988).p>

    A test similar to the DLCT has been created using numbers instead of letters. The patient is asked to cancel all the 1s and 4s from the rows of numbers. Normative data for this form of the DLCT was gathered from 51 elderly individuals (Wade et al., 1988).

  • Letter cancellation subtest of the Behavioural Inattention Test (Wilson, Cockburn, & Halligan, 1987).
    The patient is presented with a sheet of paper with five lines of letters (34 per line). The patient is instructed to put a mark through all the letters E and R. The maximum score is 40 (20 left, 20 right).

Client suitability

Can be used with:

Patients with stroke.

  • 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 DLCT requires language skills sufficient to identify letters. Therefore the DLCT may not be appropriate for patients with receptive aphasia.
  • The DLCT may not be appropriate for patients with poor vision as the letters may appear too small.
  • The DLCT cannot be used to differentiate between sensory neglect and motor neglect because it requires both visual search and manual exploration (Ladavas, 1994).
  • The DLCT cannot be completed by proxy.

In what languages is the measure available?

The DLCT has been used with English and French-speak patients.

A Hebrew version of the DLCT 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 extrapersonal space.
What types of clients can the tool be used for? Patients with stroke.
Is this a screening or assessment tool? Screening.
Time to administer Less than 5 minutes.
Versions None.
Other Languages The DLCT has been used with English and French-speak patients.
A Hebrew version of the DLCT has been used in some studies as part of the Behavioural Inattention Test.
Measurement Properties
Reliability
  • No studies have examined the internal consistency of the DLCT.
  • One study has examined the test-retest reliability of the DLCT and reported adequate test-retest.
Validity

Construct:
Adequate correlation with mean CT-scan damage.

Does the tool detect change in patients? Not applicable.
Acceptability
  • The DLCT should be used as a screening tool rather than for clinical diagnosis of USN.
  • Apraxia must be ruled out as this may affect the validity of test results. – This test cannot be completed by proxy.
  • The DLCT is known to be a more taxing measure of USN than the Single Letter Cancellation Test.
  • Patients must be able to hold a pencil.
  • The DLCT requires language skills sufficient to identify letters, and therefore may not be suitable for patients with receptive aphasia.
  • Patients with poor vision may not be able to complete the DLCT as the letters may appear too small.
  • The DLCT cannot be used to differentiate between sensory neglect and motor neglect.
Feasibility

The DLCT 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. No suggested cutoff score for the presence of USN is provided for the DLCT, however normative data has been published (see Gordon, Ruckdeschel-Hibbard, Egelko, Diller, Simmens, & Langer, 1984). The test is placed at the patient’s midline and is secured with tape. 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 DLCT.

Psychometric Properties

Overview

In general, cancellation tests are believed to have greater test-retest reliability than line bisection tests and are often more sensitive for detecting USN than line bisection tests (Marsh & Kersel, 1993; Azouvi et al., 2002). The DLCT has been reported to have adequate psychometric properties, including some evidence of reliability and validity, in identifying USN in the near extrapersonal 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 the DLCT.

Reliability

Internal consistency:

No evidence.

Test-retest.:

Gordon et al. (1984) examined the test-retest reliability of the DLCT using a group of 31 subjects and found adequate test-retest (r = 0.62).

Validity

Construct:

Egelko et al. (1988) found that the DLCT correlated adequately with mean CT-scan damage (r = -0.35).

Note: This correlation is negative because a high score on the DLCT indicates better performance, whereas a high CT-scan score indicates more brain damage.

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.
  • Friedmann, 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., Sano, M., Orazem, J., Weinberg, J. (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. pp1-7, 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.
  • Wade, D. T., Wood, V. A., Hewer, R. L. (1988). Recovery of cognitive function soon after stroke: A study of visual neglect, attention span and verbal recall. Journal of Neurology, Neurosurgery ,and Psychiatry, 51, 10-13.
  • Wilson, B., Cockburn, J., Halligan, P. (1987). Development of a behavioural test of visuospatial neglect. Archives of Physical Medicine and Rehabilitation, 68, 98-102.

See The Measure

How to obtain the DLCT?

The DLCT can be purchased as part of the Behavioral Inattention Test from Harcourt Assessment by clicking on the following link: http://www.harcourt-uk.com/product.aspx?skey=2906
Click here to view a copy of the DLCT as it appears in the Behavioral Inattention Test.

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