This project's pre-registration may be viewed [here.][1] Prior studies of inattentional blindness have found an effect of attention set on noticing rates. For example, in a study by Most et al. (2001), when subjects were instructed to attend to either white or black shapes, they were more likely to notice an unexpected object the more similar in luminance it was to the attended objects. When instructed to _ignore_ either white or black, they were more likely to notice an unexpected object the more distinct it was from the ignored set. However, in that study, the more similar in luminance an object was to one set, the more _dissimilar_ it was from the other set. Thus it is unclear whether it is the attended set or ignored set which drives this effect. To address this question, this study uses a set of objects that is equally similar to all of the unexpected objects: squares with a black and white checkerboard pattern. The other object set consists of white squares. The unexpected object is a black or white circles. Thus the unexpected object is equally dissimilar from both attended sets in shape, and is eiter identical in luminance to the white square or maximally different from the white square. The white and black unexpcted objects are equally different from the checkerboard. This setup yields clear predictions. If similarity to the attended set drives noticing, we should expect: - when people focus attention on the white squares, noticing rates should be higher for white unexpected objects than black ones. - when people focus attention on the checkerboards, noticing rates for white and black unexpected objects should be equal If dissimilarity to the ignored objects drives noticing, we would expect: - when people focus attention on the white squares, noticing rates for white and black unexpected objects should be equal - when people focus attention on the checkerboards, noticing rates should be higher for black unexpected objects than white ones Both patterns of notciing are distinct and dissociable, allowing us to determine whether the attended objects, the ignored objects, or both drive noticing. In the "predicted patterns" component, we provide plots of hypothetical data based on whether attending, ignoring, or both affect noticing rates. A demonstration of the task may be viewed [here][2]. Acknowledgements: Thank you to Cary Stothart for providing his inattentional blindness task code for our use in the present study. [1]: https://osf.io/zhbw9/?view_only=dc01c56f77f54f849c5bc338432c785a [2]: http://simonslab.com/mot/mot_demo.html