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The Role of Heuristics in Bias April 24, 2014

Posted by Peter Varhol in Software development.
Tags: , ,

A heuristic is what we often refer to as a “rule of thumb”. We’ve experienced a particular situation on several occasions, and have come up with a step-by-step process for dealing with it. It’s purely System 1 thinking in action, as we assess the situation and blindly follow rules that have worked for us in the past.

And heuristics are great. They help us make decisions fast in situations that we’ve experienced in the past. But when the situation only appears similar, but is really different, applying our heuristic can have a very bad effect, if it’s not right.

Here’s a real life example. Years ago, I took flying lessons and obtained my pilot’s license. One of the lessons involved going “under the hood”. The hood is a plastic device that goes over your head (see image). When the hood is down, you can’t see anything. When the hood is raised, you can see the instrument panel, but not outside of the plane.


While the hood was down, the instructor pilot in the right seat put the plane into an unusual situation. That might be a bank, or a stall, or something that was unsustainable. When he raised the hood, I was required to use the instrument panel to analyze and diagnose the situation, and recover from it.

After several of these situations, I had developed a heuristic. I looked first at the turn and bank indicator; if we were turning or banking, I would get us back on course in straight flight. Then I would look at the airspeed indicator. If we were going too slow, I could lower the nose or advance power to get us back to a cruise speed.

This heuristic worked great, and four or five times I was able to recover the aircraft exceptionally quickly. I was quite proud of myself.

But my instructor figured out what I was doing, and the next time I applied my heuristic, it seemed to work. But I was fighting the controls! It wasn’t straight and level flight. I started scanning other instruments, and discovered that we were losing over a thousand feet a minute.

At that point, my heuristic had failed. But I wasn’t able to go back and analyze the situation. My mind froze, and if it weren’t for the instructor pilot, we may well have crashed.

The lesson is that when your heuristic doesn’t work, it may be worse than starting over at the beginning. You may simply not be able to.



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