There’s Nothing Wrong With My Lifestyle
From the Anonymous Doc blog comes an excellent example of confirmation bias.
“I never used to have heart failure,” said the patient.
“Yeah, it starts to happen to people around your age, unfortunately.”
“No, you don’t understand, I never had a problem with my heart.”
“Yeah, I know.”
“So I don’t understand. I never had a problem.”
“Yeah, these things happen over time.”
“But nothing happened to cause it. So I don’t know where it came from.”
“Yeah, these things happen, lifestyle factors, genetics, over time things happen to everyone.”
“Well, I never used to have it until I got that echocardiogram. I think that caused it.”
“The echo diagnosed it, it didn’t cause it.”
“Yeah, I don’t know about that.”
“People aren’t born with heart failure. These things happen. It doesn’t help that you’re 150 pounds overweight, sedentary, high blood pressure, diabetes. We can put you on medication, but there are also lifestyle changes you can make.”
“Being overweight didn’t cause this. I’ve been overweight my whole life.”
“And it may be that at some point it starts to catch up with you.”
“Well, I’ve been overweight for years and it’s never caused any problems.”
“It contributed to the high blood pressure and the diabetes.”
“Those aren’t real problems.”
“No, they are. They can be serious.”
“But nothing was ever wrong with my heart.”
“Unfortunately, now something is.”
“I think the echo caused it.”
“That’s not something that makes sense, from a medical perspective.”
“It makes sense to me.”
“I wish you didn’t feel that way.”
The patient has a preconception: His lifestyle is healthy. Because of this belief, any information he receives from the world is interpreted in a biased way.
He says he’s never had any problems before. This is obviously wrong, since he’s got high blood pressure and diabetes. But that information was given little weight in his mind because they conflicted with his preconceived notion. This is evidenced by the fact that he said those conditions weren’t “real problems”. People often give very little attention to even glaring evidence against their beliefs.
So, if you accept the premise that he was completely healthy before he went to the doctor, it makes total sense that the echocardiogram caused his problem. Evidence that keeps his beliefs intact is given high value in his mind.
Do not look at this guy and say, “Ha! What a fool!”. This system of skewed weighting of evidence could happen to anyone. In fact, you probably have false beliefs right now as a result of this bias. Yes, even if you’re an atheist.
Go back and take a second look at your beliefs. Try to look at the evidence against it in a new light. Are you being biased? Do double-blinded studies show it to be true? Try to disprove your beliefs, not prove them.