Errol Morris on Confirmation Bias (Does your brain frame the picture?)

I would never set myself up as somehow the oracle of truth or value-free judgment. You know, I’m really not that different from the next guy. . . . I am a contrarian. I think I can admit to that. Looking at the MacDonald case, I was bothered by it. I don’t know how else to describe it. There’s a line in a Robert Mitchum film noir where Mitchum says, “I could see the frame, but I couldn’t see the picture.” It’s one of the great film noir lines. . . .

It’s not so much that I could see the frame but I couldn’t see the picture – this was certainly true in The Thin Blue Line 25 years ago. Here, there was something deeply unconvincing about the case that had been made, particularly the case that had been made by Joe McGinniss in Fatal Vision... too pat, too slick, too simple, too easy. What’s so interesting about this story?

When you have a theory – say you’re an investigator, which would be the best and easiest way of talking about this – you have a theory about what happened, a theory about who did it or how they did it. The term confirmation bias – I hesitate to use it, but . . . you have a theory. The question is, does that theory in some way determine the kind of evidence that you look for and the kind of evidence that you reject?

If you truly believe there were no intruders in the house and that Jeffrey MacDonald was the person who killed his family, you may not look for evidence that suggests that there were intruders in the house. You might not even notice it. It might become for all intents and purposes invisible to you. I wrote a book prior to this book, Believing Is Seeing, which is – I almost think the title should have been Disbelieving Is Seeing because it shows you this interplay between how we see things and the beliefs that we hold about the world.

Vision, which we often like to think of as neutral or value-free, is anything but that. We see on the basis of what we believe, not the other way around. And that idea is very much part of a Wilderness of Error as well. Cops come on a scene, look around, see the position of furniture. And often you quickly – I think this is a human problem – you come to one narrative or another, an explanation of what I’m looking at.

What is this? How do I explain this? What happened here? Who’s responsible? Who’s the real perpetrator? And so on and so forth. In the case of MacDonald, the police very quickly decided it was him, not just that it was him but that he had staged the crime scene, he had arranged the crime scene to make it look like there had been intruders.

But he had done it in such a ham-handed pathetic way that it was easily unmasked as a fraud. . . . You idiot! Look at this! . . . This is a pathetic attempt to deceive us into thinking that there were intruders when we know better. We know there were none. So there you go. You have an idea, a theory, and as a result of that theory how did it affect the next 40 years?

Yes, it affected the next 40 years in many very powerful and sad ways.