The effect of a visual indicator on rate of visual search Evidence for processing control

Search rates were estimated from response latencies in a visual search task of the type used by Atkinson et al. (1969), in which a subject searches a small set of letters to determine the presence or absence of a predesignated target. Half of the visual displays contained a marker above one of the letters. The marked letter was the only one that had to be checked to determine whether or not the display contained the target. The presence of a marker in a display significantly increased the estimated rate of search, but the data clearly indicated that subjects did not restrict processing to the marked item. Letters in the vicinity of the marker were also processed. These results were interpreted as showing that subjects are able to exercise some degree of control over the search process in this type of task.