The effect of cueing in a visual signal detection task

In a signal detection task four subjects were presented with stimulus cards, 50% of which contained a capital O in one of the four quadrants. Fifty per cent of these Os were surrounded by a small rectangle. This small rectangle served as a simultaneous cue, indicating the region where the O could appear. The other 50% were surrounded by a big rectangle encompassing the whole field. Fifty per cent of the blank cards contained a small rectangle, the other 50% a big one. Exposure duration was set at 15 and 20 ms. The results indicated that subjects, for whom these exposure durations led to performance exceeding chance level, used the simultaneous cue for reducing the field to be searched, resulting in higher sensitivity (d') in the small rectangle condition. Results were interpreted in terms of increasing efficiency of search as a result of which a higher quality of the icon was available for making decisions about the presence of the O.