Spatial precues affect target discrimination in the absence of visual noise.

In 2 earlier sets of experiments, the author reported that shape discrimination in an otherwise empty visual field is facilitated when the target shape is preceded by a valid spatial precue (J. M. Henderson, 1991; J. M. Henderson & A. D. Macquistan, 1993). L. Shiu and H. Pashler (1994) recently suggested that these earlier results were due to the presence of multiple posttarget pattern masks. They concluded that precue effects are observed only when visual noise is present. The author reviews the existing evidence and presents new data supporting the view that spatial precues influence shape discrimination in the absence of visual noise, consistent with a limited capacity conception of visual-spatial attention.