If you walked into a toilet cubicle and saw a bomb strapped to the back of the door, would you know if it were real? You’d just run. And you would be right to. It’s difficult to tell the difference unless you’ve had years of bomb disposal training. Sometimes not even the smartest computerised system can do it.
With practice, the brain can spot distinctions so subtle they’re impossible to describe. In an experiment, humans and computers were asked to spot rocks and mines using sonar detection systems in a submarine. In time, sonar operators could tell if an object was a mine or a rock, but they couldn’t explain why. Yet the computers still struggled.
This form of brain training can also be seen in – don’t laugh – professional chicken sexers. To the untrained eye, male and female chickens’ genitals look the same. Experts learn to tell the gender of a chicken quickly and accurately – but they can’t describe the exact differences.
Sometimes, despite all the brain’s potential to spot detailed discrepancies, the safest thing to do with a dummy bomb left behind at a football stadium is to leg it and let the professionals conduct a controlled explosion.
Dr Daniel Glaser is director of Science Gallery at King’s College London
