Transient covert attention increases contrast sensitivity and spatial resolution: Support for signal enhancement

Three studies provide experimental evidence indicating that transient attention can improve early visual processes-contrast sensitivity and spatial resolution-via signal enhancement. To assess the effects of transient attention this chapter compares performance with a peripheral cue that appeared adjacent to the target location, to that with either a central-neutral cue, which appeared either in the center of the display, or a distributed-neutral cue, that was designed to spread observers' attention across the possible target locations. In all three studies, it is evaluated that whether the magnitude of the cueing effect varied as a function of location uncertainty; this was manipulated by varying the stimulus contrast, the performance level, and the presence of a local post-mask, and was assessed by performance in a localization task. By eliminating all sources of added noise, the psychophysical studies that are reported in the chapter have shown that transient attention can increase contrast sensitivity and spatial resolution via signal enhancement.