Quantitative and Qualitative Differences in the Top-Down Guiding Attributes of Visual Search

It is generally assumed that there is a category of undoubted guiding attributes in visual search: color, motion, orientation. Any differences between these attributes are a matter of degree, rather than kind. This assumption has led to a preferential use of color in experiments that involve top-down guidance, because it provides the strongest effects. Yet, results observed for color are considered representative for the other undoubted attributes. This article reports 7 experiments that compare the top-down guiding strengths of color. motion, and orientation by adding them to a T versus L search. Giving some of the Ls a different color, motion status, or orientation should make the T easier to find, because those Ls cannot possibly be the target. The results show that whereas adding color or motion does indeed improve search performance. adding differently oriented Ls actually makes search harder, especially on absent trials and even when there are only very few items that could be the target. There were also some subtle differences between color and motion. So, rather than a single category of undoubted guiding attributes, there seems to be a clear ranking, with color at the top and orientation at the bottom. It may therefore be unwise to think that results found with color will translate one-on-one to other attributes like motion and orientation.