Reliability and construct validity of the Bells Test

Resumen

The Bells Test (BT) is a cancellation task which is widely used in the diagnosis of spatial hemineglect, and the detection of impairments in attention, perception, praxis and executive functions in patients with neurological and psychiatric data. This instrument, as well as a second, more complex version including visually-related distractors, have been adapted for use in Brazilian Portuguese. The aim of this study was to evaluate the reliability and the construct/convergent validity of both versions of the test. The sample included 66 healthy adults aged between 19 and 75 years. Reliability was examined using correlations and paired-samples T-tests of test and retest scores on both version of the test. Validity was assessed by comparing performance on the two versions of the BT test with scores on the focused attention test (AC-15), sustained attention test (AS) and the WAIS-III Symbol Search and Digit-symbol coding subtests. Results showed significant positive correlations between test and retest scores on both versions of the task, as well as moderate correlations between the number of omissions on the BT and on other measures of attention. In conclusion, both versions of the instrument were found to be reliable and valid for use in the Brazilian population.