I find this study to be slightly unfair - if you're a trained expert in detecting tumors, then your eyes are looking for undefined shadows and tumor-like growth, not for gorillas. If looking for gorillas was their training then they'd spot it in a heartbeat.
In the end, what is this trying to say? The paper says that the experts were better at detecting lung growths than the novices (thankfully), so all is well?
Edit: Looking at the pictures, it's clear that they shortly hovered over the gorilla. Maybe there's a "The Emperor's New Clothes" effect here at work? No-one wanted to report the gorilla in fear of being made fun of?
The experts may be looking for tumors and not gorillas, but what if it wasn't a gorilla but also not a tumor?
Imagine a doctor performing an ultrasound on a pregnant woman... A tumor may very well go unnoticed even if the doctor looks directly at it, just because he isn't looking for tumors.
In the end, what is this trying to say? The paper says that the experts were better at detecting lung growths than the novices (thankfully), so all is well?
Edit: Looking at the pictures, it's clear that they shortly hovered over the gorilla. Maybe there's a "The Emperor's New Clothes" effect here at work? No-one wanted to report the gorilla in fear of being made fun of?