Radiologists spend a great deal of time looking at images produced by high-tech machines, like CT and MRI scanners, that have become standard only in the last few decades. The techniques of visually scanning through the images to find peculiar spots seem to come from a much more distant past when humans were still foraging for food, according to a study by Duke University researchers.
Turns out that how a visual search is conducted is very much based on the expectations of the searcher in finding appropriate targets. Once the person believes that everything to be found has already been identified, the search stops. The scientists believe that managing expectations to prime the searcher to expect more finds should help folks like radiologists (and airport X-ray techs) to successfully find more of what they’re looking for.
From the study abstract in Psychological Science:
Separate groups of individuals searched displays with the number of targets per trial sampled from different geometric distributions but with the same overall target prevalence. As predicted by optimal foraging theory, results showed that individuals searched longer when they expected more targets to be present and adjusted their expectations on-line during each search by taking into account the higher-order, across-trial target distributions. However, compared with modeled ideal observers, participants systematically responded as if the target distribution were more uniform than it was, which suggests that training could improve multiple-target search performance.
Abstract in journal Psychological Science: A Bayesian Optimal Foraging Model of Human Visual Search
Duke press release: Looking for Tumors, Handguns