This experiment highlights that we are only aware of a small part of our visual world at any one time. We focus our attention to filter out distractions, but in focusing on what we are trying to see, we tend not to notice the unexpected. This explains why in the past, many patients were killed by accidental injections of potassium chloride solution, which was stored alongside sodium chloride (used as a flush) in identical packaging on wards. A human expecting to see sodium chloride could easily read the label yet miss that it said potassium chloride. The answer to this problem was straightforward – potassium chloride is no longer stocked on wards.
Making healthcare safer is about embedding the 'human factor' in the design of equipment; creating systems and processes that make it easy for people to do the right thing; staffing ratios, duty periods and breaks; training in error, the limitations of human performance and communication within teams. It took aviation 30 years to embed human factors in its practice, a journey healthcare is only just beginning.