The effect of spatial attention on memory scanning.

Participants responded to probe letters after sets of two, four, and six letters were memorized (Sternberg, 1966, 1969b). Spatial attention was controlled by central arrow cues and stimuli were presented in a clear or a visually degraded from. Overall RT was shorter for attended than for unattended locations, and shorter for clear than for degraded stimuli. Even though the function relating RT to memory-set size for stimuli in attended locations had a significantly smaller zero-intercept than the function for unattended locations, she slope was unchanged, which suggests that attention did not influence the memory-scanning stage. Visual quality interacted with attention, which suggests that they influenced the same stage of processing, presumably the early visual-encoding stage of processing.