Attention to visual displays during a vigilance task. I. Biasing attention.

Five experiments are described in which subjects were asked to search visual displays and report the appearance, at any location on the display, of a spot of light which persisted for one second. On displays with and without a rotating radial line it was found that subjects detect fewer such spots of light near the periphery of the display. By modifying a radar-like display in order to facilitate a changed pattern of visual search, it was demonstrated that more peripheral spots could be detected.