A few years ago, I gave a patient assessment lecture to a group of EMTs. Early in the lecture, I announced that my assistant would be coming around with a handout. The assistant was a portly gentleman sporting a wide, ugly tie with yellow splotches. After standing in front of each student to distribute the material, he left the room.
Midway through the lecture, I asked the participants to describe his tie, thereby emphasizing the importance of observation to patient assessment. Most participants could not describe the tie or my assistant with any degree of accuracy. About 15 to 20 percent gave a fairly precise description of the tie, generally including the term ‘ugly,’ and a few must have been asleep as they wanted to know, “What assistant?”
The term for this aptly demonstrated phenomenon is ‘inattentional blindness’ because while we look, we don’t see. The information doesn’t register because our brains are focused elsewhere and ignoring the visual input. This may not pose a huge problem during a lecture, but can prove to be quite a predicament in the field.
How does our vision work?
Light waves (electromagnetic waves) are continuously bouncing off every object around us. Those light waves in the visible range (we can’t process ultraviolet or infrared waves) that get past the cornea and pupil then hit the retina in the back of the eye. The retina creates electrical signals that are transmitted to the brain, which in turn interprets the information and produces the vision that we ‘see.’ Don’t believe me? Close your eyes. What do you see?
Signal interpretation
Do we ‘see’ all the visual signals we receive? From where you are right now, stop reading and take a 180-degree or half-circle view of your surroundings, then close your eyes and recall what you just ‘saw.’ Now repeat the scan slower, paying attention to details and taking note of what you do not ‘see.’ All of the light waves bouncing off the objects in your visual field hit the retina and produce visual signals for the brain. Why did your brain fail to give you the total picture of what you saw? Information overload in any system can decrease performance, including your brain. To a significant degree, you determine what you see by the extent of attention you apply to what you are looking at or looking for. A lot of the visual input from the eyes to the brain never gets to perform on your brain’s visual screen because you do not pay attention to the content. This can be both a blessing and a curse.
Blessing
Can you imagine trying to start an IV in a nice fat vein but as you start to insert the needle your vision is overwhelmed with mental images of surrounding objects such as the patient’s clothing, the cot, the blood on the floor, etc., etc., etc.? You would likely be hard-pressed to hit the vein. Our ability to concentrate visual signals on the task at hand helps us select the visual information we need to get the job done.
Curse
But what happens when we fail to recognize important visual input? Think about the last time you were providing patient care and asked yourself, “Where did THAT come from?” It might be when the visual input about your patient’s cyanotic lips and weak respirations were sidelined by the visual input of the bloody, deformed open femur fracture, or when you did not ‘see’ that large pool of blood on the floor before you kneeled down. Or perhaps you found yourself in such a situation after your failure to notice a weapon on the ground. All these events occurred within your field of vision, but failed to register with your brain.
Inattentional thinking
Inattentional blindness has a partner called ‘inattentional thinking.’ Dispatch sends you to the third intoxicated, unresponsive individual of the day or to the chronic back pain patient that you have visited too many times before. The danger is thinking that the problem is going to be the same as before, or that the scene is as safe as it was the last time you were there. If we fail to consciously evaluate the scene every time, or assess the patient every time regardless of presentation or how many times we have previously seen the patient with the same complaint, we may miss scene hazards or fail to benefit from an accurate patient assessment. What if the intoxicated patient noted above is not just drunk this time, but has a subdural hematoma that occurred from an unwitnessed fall, producing a dilated pupil that we did not think to check? What if the chronic back pain patient on this trip has an expanding abdominal aortic aneurysm that we failed to find because we did not think to examine the abdomen for a pulsatile mass? How many other ‘what if’ scenarios could feasibly exist?
Summary
We all fall victim to unwanted inattentional blindness and thinking. Decreasing the frequency of its occurrence requires awareness, and awareness is fueled by knowledge. If this is your first look at inattentional blindness, I would encourage further study. Resources include Blink, a book on this topic by Malcolm Gladwell, as well as print and video resources readily available by searching the Internet. In the mean time, keep your eyes open and pay attention out there.
References
1. Rensink RA, O’Regan JK, Clark JJ. To See or Not to See, The Need of Attention to Perceive Changes in Scenes. Psychological Science. 1997:8; 368-373.
2. Simons DJ, Chabris CF. Gorillas In Our Midst: Sustained Inattentional Blindness For Dynamic Events. Perception. 1999. 28; 1059-1074.
3. Rensink RA. When Good Observers Go Bad: Change Blindness, Inattentional Blindness, and Visual Experience. Psyche. 2000:8.
4. Rensink, RA. Seeing, Sensing, and Scrutinizing. Vision Research. 2000:40; 1469-1487.