Focal attention in visual search.

Visual search operates in different modes assumed to reflect serial and parallel processing. The basis of this distinction is not yet clear. It is often assumed that serial search involves sequential shifts of focal attention across a scene and that no such shifts occur in parallel search. Direct measurements of attention effects during search show that the focus of attention moves to the target (and away from non-targets) both in serial and parallel search. This suggests that the two search modes do not differ in their attentional load but perhaps in the way in which focal attention is directed to the target.