Here's a classic example — Page 185, Lesson 302

I want to walk you through a specific danger in how we build our mental picture of the world around us, and then we'll look at some illusions that can fool us even while taxiing on the ground. Let's start with the core idea: when we perceive something, our brain doesn't just passively record what's there. It actively fills in missing portions of the text or scene to match what the individual believes is correct. The danger here is that what the individual fills in will depend greatly on that individual's previous experience and expectation. In other words, two people can look at the same incomplete information and construct completely different mental models based on their own backgrounds. Here's a classic example. Consider the following: P y o l g s t. A psychology student would probably read it as "Psychologist," whereas a biology student could read it as "Physiologist." Same letters, same gaps — but each person's training and expectation fills in the blanks differently. That's the point. One must use extreme caution to ensure that we do not construct our mental model according to our wishes or desires. We have to guard against seeing what we want to see rather than what's actually there. Now let's move to a very practical application: illusions when taxiing. Even on the ground we are not free of illusions. The first one involves relative movement. A loading bridge moving away from the aircraft may give an illusion that it is the aircraft that is moving. You're sitting in the cockpit, you see the jet bridge slide backward, and your brain might tell you that you're the one drifting forward. When arriving at a gate which itself may be moving — some gates have moving walkways or the bridge itself is repositioning — the pilot may believe that the aircraft is stationary and apply the parking brake, perhaps causing cabin staff to be thrown forward with the danger of injury. That's a real safety hazard: a sudden stop when you thought you were already stopped. The next illusion involves blowing snow. This can give a false impression of relative speed. Let me break down two scenarios. When an aircraft is taxiing with a tailwind, the snow may appear to be falling vertically, giving the impression that the aircraft has stopped, when in fact it may still have a relatively fast taxiing speed. Think about it: if you're moving forward and the wind is coming from behind at the same speed, the snowflakes appear to drop straight down, just like they would if you were stationary. Application of the parking brake in these circumstances again could have serious consequences. Alternatively, the aircraft could creep forward, colliding with an obstacle, when it was thought to be stationary. Now the opposite case: when taxiing into a headwind, the blowing snow will give the illusion that the aircraft is taxiing faster than is the fact. The snow rushes toward you more aggressively, making you think you're going faster than you really are. In either case — tailwind or headwind — the pilot must look out of the side cockpit windows to gain an accurate assessment of taxi speed. Your forward view through the windscreen can be deceptive because of the snow's motion relative to the wind. The side windows give you a better perspective on how fast the ground is actually moving past you. So the key takeaway here is that our expectations and experience shape what we perceive, and even on the ground during taxi, illusions from relative movement and blowing snow can lead to dangerous misjudgments if we don't use proper cross-checking techniques — like looking out the side windows.