The Amazing Colour Changing Card Trick To start off, I need you to do a quick exercise. Don't worry, it's not difficult, and I promise you're going to love this. I want you to watch this short video clip called the "Colour Changing Card Trick" which starts with a blue-backed deck of playing cards. Some of my readers have experience with card magic, but even if you catch the moves or know how this works, I think you'll enjoy this a lot: So did you catch the moves? Or were you completely fooled, and did the colour changes completely fly by you? This is a fine example of a psychological phenomenon that we'll explain later. But first, let's try another little test. A Quick Test About Playing Cards To illustrate the same phenomenon, let's quickly test your knowledge about playing cards. If you're reading this, chances are you have used playing cards a lot. Perhaps you use them for playing card games, for performing card magic, for cardistry, or you're just a collector. Either way, you've probably shuffled a deck hundreds if not thousands of times. Shuffling, dealing, and holding a hand of cards - it's likely all second nature to you right? Well, then you should have no problems answering some simple questions about the playing cards that you have seen many, many times, right? Let's assume a normal deck of traditional playing cards, like your standard Bicycle deck produced by the United States Playing Cards. Are you ready? You're going to ace this test, surely! But strictly no guessing - if you don't know an answer, just leave that question blank. Here we go: 1. Including black as a colour, how many different print colours do regular court cards have? 2. How many of the twelve court cards are looking to the left? 3. How many court cards are shown with a side view of the face rather than a front view? 4. Which Queen is holding something besides a flower? 5. Which King is not holding a sword? 6. Which Jack is holding a paddle/mirror? 7. Which Jacks have a fancy moustache? 8. Which Kings do not have a moustache? 9. What is the only suit where the Jack and Queen are not looking in the same direction? 10. How many of the 52 cards in a regular deck have an asymmetrical (one-way) design? So how did you do? No, I'm not going to tell you the correct answers, because you might just cheat. I know that I would be tempted to do so, if someone gave me a test like this! So write down your answers, and then actually grab a physical deck of playing cards, and see for yourself. Seriously. You might be surprised at the results! And you might notice some details on those cards that you've never noticed before. If you get a passing mark of more than five right, I'll be very impressed. And if you did find that test too difficult, try this slightly easier online pop quiz about playing cards which will instantly give you a score out of ten. Inattentional Blindness Going through these questions has likely made you realize how little you've noticed about the playing cards that you've seen many, many times. Strange isn't it?! How can it be possible that you have handled a regular deck of playing cards so often, and yet not know the answers to basic questions like these? I first came across these questions (which I've modified) in a blog post by Jan Isenbart, who is a magic enthusiast from Germany. He used this simple test to illustrate a phenomenon that psychologists call inattentional blindness, or change blindness. The idea of this is that when our attention is focused on something specific, it is possible for something else that happens right in front of our eyes not to register at all. Perhaps the most well known example of this is shown in the following video. It shows the results of a Selective Attention Test, that was part of a prize-winning experiment devised and run by two American psychologists, Daniel Simons and Christopher Chabris. Many of you may already have come across this previously, but for those who haven't, what you need to do is the following: Count how many times the players wearing white pass the basketball." Stop reading this article and give it a try, and do genuinely concentrate and do the counting as instructed. The final result may surprise you. Similar to this test is another one called The Monkey Business Illusion. If you're interested in reading more about this, check out the website from Simons and Chabris. It's a companion to their best-selling book The Invisible Gorilla. Some of the videos they have produced to illustrate inattentional blindness make for fun viewing. Daniel Simons' article "Failure of Awareness: The Case of Inattentional Blindness" is also a good read on the topic.