One of the priorities of BBSPB and BRP is to improve cancer detection and diagnosis through perceptual and cognitive research on cancer image perception. While progress can be made in this area by testing lay observers, studying trained professionals, such as radiologists, is key to the success of this scientific endeavor. However, it is often difficult for researchers to get enough radiologists to participate in their experiments. One solution to this problem is to go where the radiologists are: the Radiological Society of North America (RSNA) meeting, which attracts roughly 20,000 practicing radiologists. Individual labs had tried this strategy in the past, on an ad hoc basis, with limited results. The NCI Perception Laboratory at RSNA provided a shared facility for investigators to recruit and test radiologist observers in a high-visibility location with support from the meeting organizers. Eight laboratories from the US, Australia, Canada, and the UK participated, collectively running 172 participants over five days.