How did you not see that? #WILTW

This is the 159th #WILTW

You don’t need to have any medical expertise to spot the abnormality in this CT Scan

Drew et al. Psychol Sci. 2013 Sep; 24(9): 1848–1853.

If it took you a bit of time, don’t worry. Not an insignificant number of experienced radiologists missed the gorilla in the top right corner too.

While these cognitive games are good fun there application in real world medicine isn’t always clear i.e. if you’d swallowed a toy gorilla would it really be missed? It’s becoming clear there is a growing body of evidence that inattentional blindness does impact on the clinical decisions made by healthcare professionals.

Inattentional Blindess: The failure to see visible and otherwise salient events when one is paying attention to something else

In a talk to the International Paediatric Simulation Society this week Christopher Chabris presented his own research on the subject. It stems from a high profile incident in the United States when a police officer (Kenny Conley) was convicted of obstruction of justice and perjury because he failed to spot a fellow officer (Michael Cox, who was in plain clothes) being assaulted by other officers who had allegedly mistaken Michael as a felon. The prosecutors argued given Kenny Conley had run straight past Michael Cox it would have been impossible for him not to have seen the assault.

Professor Chabris ran an experiment where subjects (college students) were instructed to follow someone running in front of them and count the number of times the person they were chasing touched the top of their head. The volunteers were not told that they would run past a staged assault during the 400m run. Even during the day only 56% of the students noticed the fight that was happening right in front of them (video of the study here)

It does seem possible that once focused on an activity you may literally become blind to events around you. This misperception reveals itself in a number of ways. In the picture below (click here if it doesn’t work) can you see what is changing between the flicks of the screen?

It’s possible you may have spotted it instantly but certainly in the lecture theatre I was in at least half the audience of over 350 people took at least 30s, if not longer to find it.

Inattentional blindess may have a significant impact on medical practice. While it may seem astounding to an outsider that the falling oxygen levels or heart rate weren’t spotted, it may well be the staff simply couldn’t see the numbers changing on the monitor. And if they stop looking at the patient, to draw up drugs for example, you can see how sudden deterioration can be missed. It follows on the more stressed or distracted you are, the more likely that inattentional blindness may occur (although I am not aware of the specific evidence behind this). My colleague Gareth Lewis highlighted the reasons for poor performance in simulation may well be the anxiety of undertaking the exercise impacts on the ability to act on information provided in the scenario.

If nothing else the concept makes real the dangers of doing something as simple as glancing at your phone in the car. But I think it is also worth re-thinking your reaction the next time someone claims to have missed something that should have been in full view.

What have you learnt this week #WILTW

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