Intra- and cross-dimensional visual search for single-feature targets

Cross-dimensional visual search for single-feature targets that differed fr om the distracters along two dimensions (color and orientation) was compare d with intradimensional search for targets that differed from the distracte rs along a single dimension (either orientation or color). The design of th e first three experiments differed from those of previous studies in that p articipants were required to respond differently to each of the targets. Ex periments 1-3 were similar except that in Experiment 1, the distractors wer e homogeneous; in Experiment 2, two types of distracters were used in equal proportions; and in Experiment 3, two types of distracters were used but o ne of the distracters was a singleton. The findings, contrary to those of p revious studies, revealed that cross-dimensional search is at least as effi cient and for some targets even more efficient than intradimensional search . These results suggest that the details of stimulus-to-response mapping ar e essential in comparing intra- and cross-dimensional tasks. Experiment 4 u sed a priming design and did not support an explanation based on grouping p rocesses. We outline an explanation for all the findings based on a recent cross-dimensional response selection model by Cohen and Shoup (1997).