Bells Test

Purpose

The Bells Test is a cancellation test that allows for a quantitative and qualitative assessment of visual neglect in the near extra personal space.

In-Depth Review

Purpose of the measure

The Bells Test is a cancellation test that allows for a quantitative and qualitative assessment of visual neglect in the near extrapersonal space.

Available versions

The Bells Test was developed by Gauthier, Dehaut, and Joanette in 1989.

Features of the measure

Items:
There are no actual items to the Bells Test.

In the Bells Test, the patient is asked to circle with a pencil all 35 bells embedded within 280 distractors (houses, horses, etc.) on an 11 x 8.5 – inch page (Figure 1). All drawings are black. The page is placed at the patient’s midline.

Figure 1. Bells Test

The objects are presented in an apparently random order, but are actually equally distributed in 7 columns containing 5 targets and 40 distractors each. There is a black dot on the bottom of the page to indicate where the page should be placed in relation to the patient’s midsaggital plane. Of the 7 columns, 3 are on the left side of the sheet, 1 is in the middle, and 3 are on the right. Therefore, if the patient omits to circle bells in the last column on the left, we can estimate their neglect is mild. However, omissions in the more centered columns can suggest a greater neglect of the left side of space.

The examiner is seated facing the patient. First a demonstration sheet is presented to the patient. This sheet contains an oversized version of each of the distractors and one circled bell. The patient is asked to name the images indicated by the examiner in order to ensure proper object recognition. If the patient experiences language difficulties or if the examiner suspects comprehension problems, the patient can instead place a card representing that object over the actual image.

The examiner gives the following instructions: “Your task will consist of circling with the pencil all the bells that you will find on the sheet that I will place in front of you without losing time. You will start when I say “go” and stop when you feel you have circled all the bells. I will also ask you to avoid moving or bending your trunk if possible.” If a comprehension problem is present, the examiner has to demonstrate the task.

The test is then placed in front of the patient with the black dot (see arrow on Figure 1) on the subject’s side, centered on his midsagittal plane (divides the body into right and left halves). The test sheet is given after the instructions.

The examiner holds the scoring sheet (Figure 2) away from the patient’s view, making sure the middle dot is towards the patient. This upside-down position will make scoring easier for the examiner. After the patient begins the test, the examiner records the order of the bells circled by the patient by numbering the order on his/her scoring sheet (e.g. 1, 2, 3,…). If the patient circles another image (an image that is not a bell), the examiner indicates on his/her scoring sheet the appropriate number and the approximate location. The subsequent bell receives the next number.

Figure 2. Examiner scoring sheet.

If the patient stops before all the bells are circled, the examiner gives only one warning by saying “are you sure all the bells are now circled? Verify again.” After that, the order of numbering continues, but the numbers are circled or underlined. The task is completed when the patient stops his/her activity.

Scoring:
The total number of circled bells is recorded as well as the time taken to complete. The maximum score is 35. An omission of 6 or more bells on the right or left half of the page indicates USN. Judging by the spatial distribution of the omitted targets, the evaluator can then determine the severity of the visual neglect and the hemispace affected (i.e. left or right).

The sequence by which the patient proceeds during the scanning task can be determined by connecting the bells of the scoring sheet according to the order of the numbering.

Time:
Less than 5 minutes.

Training:
None typically reported.

Subscales:
None.

Equipment:

• The test paper (8.5″x11″ page with 35 bells embedded within 280 distractors).
• Pencil
• Score sheet
• Stopwatch

Alternative forms of the Bell’s Test

None.

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 visually discriminate between distractor items, such as the images of houses and horses, and the bells that are to be cancelled.

Should not be used with:

• As with other cancellation tests, the Bells Test cannot be used to differentiate between sensory neglect and motor neglect because it requires both visual search and manual exploration (LÀdavas, 1994).
• The Bells Test cannot be completed by proxy.

In what languages is the measure available?

Not applicable.

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	Not applicable.
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 Bells Test. Test-retest: No studies have 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 Bells Test.
ValidityThe degree to which an assessment measures what it is supposed to measure.	Criterion: One study reported that the Bells Test is more likely to identify the presence of neglect than the Albert’s Test in 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.. One study found that the Bells Test and the Letter Cancellation Test were more likely to detect the presence of neglect than the Line Bisection Test in 35 patients with spatial neglect. Construct: Known groups: The Bells Test was able to discriminate between patients with right cerebral lesions and patients with left cerebral lesions.
Does the tool detect change in patients?	Not applicable.
Acceptability	The Bells Test 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 visually discriminate between distractor items to complete. The measure cannot be used to differentiate between sensory neglect and motor neglect.
Feasibility	The Bells Test requires no specialized training to administer and only minimal equipment is required (a pencil, a stopwatch, the test paper and scoring sheet). The test is simple to score and interpret. The test is placed at the patient’s midline and a demonstration sheet is used to familiarize the patient with the images used in the test. The examiner is required to follow along with the patient as they circle each bell, and record on the scoring sheet the order in which the bells are cancelled. Upon completion of the test, the examiner must count the number of bells cancelled out of a total of 35, and record the time taken by the patient. An omission of 6 or more bells on the right or left half of the page indicates USN.
How to obtain the tool?	You can download a copy: Bell’s Test

Psychometric Properties

Overview

A review of the Bells Test reported that the measure has excellent 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 Test (Marsh & Kersel, 1993; Azouvi et al., 2002).

For the purposes of this review, we conducted a literature search to identify all relevant publications on the psychometric properties of the Bells Test.

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 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 Bells Test.

Test-retest:
No studies have 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 Bells Test.

Validity

Criterion:
Vanier et al. (1990) administered the Bells Test and the Albert’s Test to 40 neurologically healthy adults, and 47 patients with right brain 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.. It was found that 38.3% of patients were diagnosed with USN using the Bells Test (with a cutoff score of greater than or equal to 4), compared with only 10.6 % with the Albert’s Test (using a cutoff score greater than or equal to 2). The results of this study suggest that the Bells Test is more likely to identify the presence of neglect than the Albert’s Test in 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..

Ferber and Karnath (2001) examined the ability of various cancellation and line bisection tests to detect the presence of neglect in 35 patients with spatial neglect. The Bells Test detected a significantly higher percentage of omitted targets than the other tests (Line Bisection Test, and 3 cancellation tests: Letter Cancellation Test, Star Cancellation Test and Line Crossing Test). The Line Bisection Test missed 40% of patients with spatial neglect. The Letter Cancellation Test and the Bells Test missed only 6% of the cases.

Construct:
Known groups:
Gauthier et al. (1989) examined the Bells Test in 59 subjects, of which 20 were controls, 19 had right cerebral lesions and 20 had left cerebral lesions. A statistically significant difference in mean scores between the group with right cerebral lesions and the group with left cerebral lesions was observed.

Responsiveness

No studies have examined the responsivenessThe ability of an instrument to detect clinically important change over time.
of the Bells Test.

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.
• Ferber, S., Karnath, H. O. (2001). How to assess spatial neglect–Line Bisection or Cancellation Tests? J Clin Expl Neuropsychol, 23, 599-607.
• Gauthier, L., Dehaut, F., Joanette, Y. (1989). The Bells Test: a quantitative and qualitative test for visual neglect. Int J Clin Neuropsychol, 11, 49-54.
• Làdavas, 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.
• Vanier, M., et al. (1994). Evaluation of left visuospatial neglect: norms and discrimination power of the two tests. Neuropsychologia, 4, 87-96.

See the measure

How to obtain the Bell’s Test

You can download 

• BELL-STIMULI
• Bells Test Instructions
• Gauthier L, Dehaut F, Joanette Y, 1989