Attending to horizontal, diagonal, and vertical positions in space

Vocal reaction times were measured for a target letter presented in one of eight possible locations surrounding fixation. The letter was preceded by a single dot marking its expected location (focused attention condition); by a pair of diametrically opposite dots, one of which marked the expected location of the target (divided attention condition); or by eight dots occupying all eight positions in which the target may appear (distributed attention condition). Under all three conditions, targets occupying horizontal positions were responded to faster than those presented in other positions. Moreover, under the focused attention condition, diagonal targets were responded to faster than vertical targets. The results suggest an uneven distribution of attention across the visual field.