Attention to overlapping objects: Detection and discrimination of luminance changes

Selective attention to 1 of 2 overlapping objects was assessed in a cuing p aradigm. Participants detected or identified targets that appeared in 1 of 6 possible target locations (3 on each object). Significant cuing effects f or the simple detection of such targets using both reaction time and sensit ivity measures of performance were found. Cuing effects were consistently g reater when the participants were required to identify some aspect of the t arget even when the tasks (detection vs. identification) were equated for o verall performance level. These differences in cuing effects between tasks were much reduced if the target locations were no longer grouped into 2 obj ects. It is suggested that identical stimuli can elicit differing attention al mechanisms depending on task type (rather than task difficulty) and that these mechanisms differ in the nature of the representation of the visual world.