In an earlier experiment we investigated the effect of number of distractors on search performance. The data showed a significant increase in search time for uniquely coloured (blue) targets with increasing number of distractors. In the present experiment, designed to investigate the effect of relative positions of target and distractor(s), the target againg had the unique colour of blue. Contrary to our expectations, no distractor effect was found. These differing findings are discussed in terms of two visual search theories: Treisman's feature integration theory and the attentional engagement theory of Duncan and Humphreys. It is concluded that if visual search experiments are to yield practically relevant results, short and heterogeneous series of stimuli should be used. (A)
Samenvatting