Simple, inexpensive, and easily implemented procedures can sometimes significantly improve performance. DiVita and Hanna (1987) have pointed out that target detection on the waterfall display suffers, because the observer has difficulty in keeping the relevant bearing isolated. Performance is improved if the target bearing is simply highlighted, so that there is no question in the observer's mind as to where he is supposed to be looking. Divita's procedure requires the computer to be programmed to highlight the bearing of interest. This may be simple enough to do with a vertical bearing. In practice, however, a target track on a waterfall display may occur at any angle. This greatly increases the programming difficulties. The question arises as to whether or not a simple mechanical method of delineating a given bearing would also improve performance. In this study, we simply placed a straight-edge along the target bearing and compared target detection under that condition with performance without the straight-edge. Although the straight-edge presumably makes it easier for the operator to isolate the target bearing, target detection did not improve.