How to assess spatial neglect--line bisection or cancellation tasks?

Abstract

Spatial neglect is usually assessed using cancellation tests or line bisection. A recent comparison of these tests has revealed a double dissociation, in which one neglect patient was impaired in line bisection but not in star cancellation whereas another showed the reverse deficit. This dissociation has prompted the question whether 'neglect' is still a meaningful theoretical entity. We compared line bisection and cancellation tasks regarding their accuracy in detecting spatial neglect. We tested 35 patients with well-defined spatial neglect using a line bisection task and four different cancellation tasks. The line bisection test missed 40% of our neglect patients. Far superior were the letter cancellation and bells tests, each of which missed only 6% of the cases. A deviation in line bisection is not fundamentally related to spatial neglect, but may also arise from other causes (e.g., hemianopia, or which hand is used), and therefore, should be treated with caution in clinical diagnosis. Cancellation tests, such as the bells test and letter cancellation, are more helpful tools to detect spatial neglect.