SPATIAL ATTENTION IN VISUAL-SEARCH FOR FEATURES AND FEATURE CONJUNCTIONS

Spatial attention was measured in visual search tasks using a spatial probe. Both speed and accuracy measures showed that in a conjunction t ask, spatial attention was allocated to locations according to the pre sence of target features. Also, contrary to some predictions, spatial attention was used when a clearly distinguishable feature defined the target. The results raise questions about any account that assumes sep arate mechanisms for feature and conjunction search. The probe method demonstrated here allows a very direct measurement of attentional allo cation, and may uncover aspects of selection not revealed by visual se arch.