In an earlier blog post I wrote about
why scientists research the seemingly obvious. One of the reasons is that the results of so-called “obvious” research can be used to help inform people’s decisions, both in private life and public policy. But why do we need so
much of this evidence?
Not just being stubborn
Rebekah and Lauren
Rebekah has been one of my closest friends since I was four and she was five. And after that long a time being friends, we know each other pretty well. So when Rebekah tells me that I’m the most stubborn person she has ever met, she’s probably right – when I look back on my own behaviour I can see that once I get an idea in my head I am very reluctant to let it go.
However, I’m not alone in being unwilling to change my mind (although I may take it a little further than most). It turns out that human beings, all of us, have some fundamental flaws in the way we think, called “cognitive biases”. These flaws can affect how we form opinions and beliefs1. One of these flaws is known as the primacy error. Essentially, this means that our first impression of something, which is based on the first (not necessarily the best) evidence we encounter on that topic, is an impression we will be unwilling to change. Even if later on we are shown proof that our first impression is wrong, we still cling to that impression and resolutely ignore anything that disproves it2.
In everyday life
How does this kind of cognitive bias impact everyday life? Well, let’s look at tanning beds. Tanning beds are marketed as a safe alternative to tanning outdoors. According to the industry, you can control your exposure so you won’t get a burn and there is no risk of skin cancer.
However, over the past years more and more evidence has built up showing that indoor tanning is a risk factor for skin cancer. In fact, UV light from indoor tanning beds has been classified as “carcinogenic to humans”. So have people stopped tanning?
No they have not. Indoor tanning salons remain as popular as ever despite the increased risk of cancer3. Why? There are a host of reasons, not just one. However, our cognitive biases, those flaws in thinking that we are usually not even aware we have, may play a role. People were using tanning beds long before we knew that they were dangerous – if people have already absorbed the message that tanning beds are safe, it’s going to take an awful lot of evidence to get them to change their minds4.
The most insidious thing about the primacy error (or any cognitive bias, really) is that we are not aware of when it comes into play. Nobody deliberately rejects good evidence against their beliefs simply because of the timing through which they encountered it; instead, we think that the later evidence is not convincing or not relevant.
The best way to combat this type of bias is to think about why something seems convincing or not to you. Are you not convinced because the evidence is poor, or are you not convinced because of the primacy error? Rebekah still thinks I’m stubborn, but these days I try to make sure I’m being stubborn for the right reasons.