That fleeting moment of regret between clicking the wrong icon and seeing an unwanted web page pop onto the screen could make a huge difference in improving the accuracy of visual searches in medicine and homeland security.
Visual screening is critical to such things as early cancer diagnosis and airport security, but paradoxically the more rare the object being searched for becomes, the lower the screeners' accuracy in finding it when it is there. Screeners also tend to respond more quickly when the targets become more rare.
“Even though they're not under time pressure, people tend to hurry,” said Stephen Mitroff, an assistant professor of psychology and neuroscience at Duke University. “They get used to not seeing anything and they're just hitting that key over and over.”
When people are asked to search for an item that will appear only once in 100 images, they might miss as many as a third of the objects they're supposed to be finding. Studies of radiologists looking at images to find cancer have shown similar error rates.
But those error rates fall by more than half if test subjects are given the opportunity to immediately reconsider and correct their choices, according to a new study by Mitroff and Duke graduate student Mathias Fleck that appears in the November issue of the journal Psychological Science.
“The high error rate in studies of rare targets appears to come from what we call execution errors – the observers did notice the target, but they responded too quickly,” Fleck said. The sensation should be familiar to most web- and channel-surfers.