To investigate the nature of external noise exclusion, we compared central spatial precuing effects in 16 conditions that varied the amount of external noise, the number of signal stimuli, the number of locations masked by external noise, and the number and style of frames surrounding potential target locations. In the absence of external noise, precuing produced only marginal performance improvements in a small number of display conditions. In the presence of high external noise, precuing improved task performance in all the display conditions. The magnitude of these spatial attention effects, as gauged by contrast threshold reduction, is nearly constant across all the display conditions. This suggests that spatial attention mostly excludes external noise at the target location; the presence of external noise and/or signal stimuli in non-target regions has little effect on spatial performance when location uncertainty is eliminated by report cues. However, the presence of other potential locations for the target is critical, because if target location is known in advance, attention can be focused on that location with or without a cue.