Used 2 tasks to elucidate the nature of selective attention to individual stimuli: (a) focusing, in which 1 stimulus was classified against 3 others; and (b) condensation, which required the processing of 2 attributes. With feature-generated stimuli, 2 have a special role: the null stimulus in which all features are absent, and the complete stimulus in which all are present. A 2nd variable concerns the homogeneity or heterogeneity of the attributes. The present 11 experiments with 110 undergraduates used 4 types of stimuli and 13 tasks. The conclusions are as follows: (a) Homogeneous dimensions produced stimuli with good selective attention to individual stimuli and good condensation classification. (b) Heterogeneous dimensions produced stimuli that had separable attributes, with good selective attention to attributes but not to individual stimuli. Condensation classification was poor. (c) Homogeneous features produced stimuli that showed poor selective attention to attributes but good selective attention to individual stimuli, especially complete and null stimuli. Condensation classification was good. (d) Heterogeneous features showed good selective attention to the null stimulus and fairly good selective attention to other stimuli. Selective attention to attributes and condensation performance were fair. It is concluded that good selective attention to individual stimuli occurs either because of the special role of the null stimulus when stimuli are generated from features or because the individual stimulus is well configured. The effect is probably due to the ease with which such stimuli are held in memory. (21 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)