In my last blog post “The Experience Wall” I spoke about the dangers of clinical experience and I broke up clinical experience into 3 parts.
1) The perception of clinical events (seeing, hearing, feeling etc)
2) The memories of those events
3) The interpretation of those perceptions (cause and effect,etc)
My next three posts will look at each of these three categories in more depth.
It appears that our perceptions of the world are accurate and objective. This however is an illusion. In fact, our brains are wired to see things that we expect to see and miss objects and events which are unexpected. Christopher Chabris and Daniel Simons provided us with a powerful example of this in their famous “invisible gorilla study“. If you have not tried this experiment yourself click on the link and give it a try before reading further (spoiler alert). In their study subjects watched a video of people passing a basketball and were asked to count the number of passes. In the middle of the game, A person in a gorilla suite walks out, pauses to beat his/her chest, then walks away. About 50% of the people watching the video missed seeing the very obvious gorilla (did you see it?). This phenomenon is called inattentional blindness and we are all susceptible to it. In fact, a recent experiment performed on radiologist demonstrated how they can miss unexpected objects on a film. The researchers inserted a picture of a gorilla into the CT images of a lung. 83% of the radiologist did not see the gorilla (even though it was obvious and they looked right at it). Another common example of missing obvious things occurs when watching movies. Just about every movie has continuity errors (despite the presence of a script supervisor) and most of us never notice it. Several website are dedicated to pointing out these errors.
We miss unexpected objects and events because our brains have a finite ability to focus. For example, if I am focusing on a phone conversation, I have a reduced ability to focus on driving. I have been driving long enough that my unconscious brain can handle most of the routine tasks of driving. However, if something unexpected happens (someone pulls out in front of me) I am less likely to perceive the pending collision. This is why hands free devices do not reduce the risk of driving while talking on a cell phone. The problem is not that our hands are tied up with the phone, it is that our minds are tied up with the conversation.
In contrast if we expect to see certain objects, events or patterns we are likely to perceive them, even if they are not present. This is why some will see Jesus in a cheese sandwich (we are programmed to see faces) and hear devil worshiping when listening to stairway to heaven backwards (we are programmed to hear words). It may also be why manual therapists think they can identify small differences in movement and position even though the research suggests that we can not. Michael Shermer talks about this “pattern seeking” tendency in his book and in this Tedtalk.
The take home message is that our perceptions are biased. No matter how hard clinicians attempt to avoid it, we will under perceive unexpected objects and events, and over perceive the expected. All we can do is take this bias into account when we are determining how confident we can be in the accuracy of our experience.