In a real world search, it can be important to keep 'an eye out' for items of interest that are not the primary subject of the search. For instance, you might look for the exit sign on the freeway, but you should also respond to the armadillo crossing the road. In medicine, these items are known as "incidental findings," findings of possible clinical significance that were not the main object of search. These errors (e.g., missing a broken rib while looking for pneumonia) have medical consequences for the patient and potential legal consequences for the physician. Here we report three experiments intended to develop a 'model system' for incidental findings - a paradigm that could be used in the lab to develop strategies to reduce incidental finding errors in the clinic. All the experiments involve 'hybrid' visual search for any of several targets held in memory. In this 'mixed hybrid search task,' observers search for any of three specific targets (e.g., this rabbit, this truck, and this spoon) and three categorical targets (e.g., masks, furniture, and plants). The hypothesis is that the specific items are like the specific goals of a real world search and the categorical targets are like the less well-defined incidental findings that might be present and that should be reported. In all these experiments, varying target prevalence, number of targets, etc., the categorical targets are missed at a much higher rate than the specific targets. This paradigm shows promise as a model of the incidental finding problem.
Keywords: Errors; Hybrid search; Incidental findings; Radiology; Visual search.