Just about everyone has heard of confirmation bias and experiences it in our everyday lives. This heuristic is similar to anchoring bias but goes a step further by filtering out data that is not congruent with it.

100,000 years ago, as humans lived in hunter-gatherer societies, life spans were short (20 to 30 years), and having to learn lessons more than once could be fatal before passing on their genes. Those who did not recognize friend from foe, or who was part of the tribe or not, did not live to pass on their genes to us.

Therefore, each of us has inherited this hardwired tendency.

The Impact of Confirmation Bias in Modern Decision-Making

We see examples of this all around us—in political, religious, and professional lives, as well as in everyday decisions. We’ve all experienced bringing overwhelming data to support our position, only to have the person we present it to reject all of it.

In today’s world, we face much more complex cognitive requirements. The data and conclusions are often not binary, not urgent, and require the synthesis of many different factors. I discussed this in my previous blog, where I talked about holding mutually exclusive ideas simultaneously until we can weigh the evidence and see how it stacks up.

Often, we may form an initial conclusion, perhaps influenced by availability or anchoring biases, and then begin filtering out data that does not support that conclusion. Sticking to a preconceived idea, even when overwhelming evidence stacks up against it, is not only counterproductive but almost guaranteed to be wrong. This, in turn, leads to additional counterproductive behaviors as we try to justify poor decision-making.

Confirmation Bias in the Foundation Diagnosis World

I have seen this play out countless times in the foundation diagnosis world. I remember a home in central Phoenix that was initially investigated by a respected engineer’s EIT (engineer in training). The EIT concluded that the west side of the home was experiencing settlement and needed underpinning because of some severe cracking on that wall. I was alarmed because the west side of the home had the highest floor slab elevations. 

Additionally, there was a large tree very close to the west wall, with large roots extending under the house. Inside, near those roots, the high elevations peaked at a sharp point, just like what would happen if the roots had lifted the slab.

Case Study: Misinterpreting Floor Slab Elevations

When I brought this to the attention of the engineer, I heard some surprising explanations, like, “Well, maybe the footing has settled, but the floor adjacent to it has not.”

That might make sense—except the floor adjacent to the footing had not only failed to settle but had actually risen. How could that be if the footing was dropping right next to it?

To make matters worse, there was no cramming in the baseboards, which would typically be visible when the stem wall and floor slab failed to move together. (See illustrations below.)

Common Misconceptions in Foundation Issues

Another common example is when a foundation expert from other parts of the country comes to the Southwest, a region with very arid conditions. No matter how much data we present, they simply cannot grasp the concept of expansive soil heave because, in the areas they come from, heave is less common and rarely plays a prominent role.

We also frequently talk with homeowners who are convinced that a sloped floor, sloping down to the perimeter, is a surefire indication of settlement in that area. It can be very challenging to convince them that there is a very real possibility the middle of the floor could be rising instead.

Confirmation Bias in Foundation Litigation

I have often seen this dynamic play out in the foundation litigation process. Plaintiff and defense experts usually carve out a niche for their practice, specializing in one side or the other, but rarely both.

Often, defense experts tell homeowners that since they have relationships with the insurance companies for home builders, they are conflicted out and cannot take a claim adversarial to them. This is convenient as it spares them from pissing off their real client, the home builder. These experts are supposed to act as dispassionate, neutral professionals, not as zealous advocates like attorneys. 

However, after many years, I have seen the erosion of this neutrality leading to covert advocacy. When this happens, groupthink fosters belief bias, which then feeds into confirmation bias, and possibly even reactance and in-group bias. We’ll be exploring these last two biases in future blogs.

Breaking the Cycle of Bias: Steps Toward Objectivity

The point is that when we allow ourselves to go down these paths, we begin to justify our behavior and often don’t even recognize the mental shortcuts our minds are taking. This is when we start making mistakes we might otherwise avoid.

If our goal is to provide the best advice for each condition, we should be on constant vigilance for these biases by getting good peer reviews and challenging ourselves with a devil’s advocate point of view…. Perhaps even encouraging an appointed devil’s advocate on our initial conclusions.