Lisa Junker (of Acronym) left a great comment on my last post about Assumptions and Complexity:

Great post, Jamie! And great advice. It’s something I’ve been thinking about lately myself, so I’d offer one addendum: Be aware of your assumptions, and also be aware of how you may be editing the information you receive to match your assumptions–even when that information goes directly against the assumption you’ve made.

For example, you’ve already made X assumption about someone, so when information that would support Y instead comes up, you either discount that information or interpret it as further evidence that the person is really X. (I think the book Stumbling on Happiness talks about this, if I remember correctly–I know I didn’t come up with it on my own.)

Being aware of this human tendency makes it a lot easier to challenge your assumptions–because it will make it easier for you to actually see the evidence that goes counter to the assumptions you’ve made.

You are absolutely right, Lisa. And I’m sure it’s been written about in a bunch of books. What I wrote about assumptions ultimately comes from Chris Argyris’ work on the Ladder of Inference, which has shown up in books like Difficult Conversations and The Fifth Discipline. The ladder simply makes a connection between the things we observe in the world, how we make sense of them, and then how we take action based on the sense we made. Things like conclusions and actions are at the top of the ladder, but the things we don’t talk about–assumptions, and the actual behaviors–are at the bottom.

And near the very top of the ladder, above conclusions, lie "beliefs." Once you get a belief about something (or someone), then as Lisa points out, you really don’t look for any observable data. You just "know" it is true. This seriously impacts what you see. Maybe I’ll write the story up for another blog post, but I was in a team situation where someone was mad because the rest of us had ignored her suggestion. I specifically didn’t remember her saying it, even though it had only happened ten minutes before. But she was able to remind ME of what my reaction was, and then I remembered it. Turns out I had already decided that she wasn’t going to contribute anything useful to the conversation, so when she did, I literally did not hear it.

We like to say, here in the U.S., that we will "believe it when we see it." A more accurate statement might be "We will see it, when we believe it." When confronted with truth that contradicts our beliefs, our brain simply shuts out the truth rather than challenge the belief.