I’m sure you must’ve come across Fins Illusion at some point in your life. Very simply:
Of the two horizontal lines A and B in the figure below, which one is longer?
If you answered both are the same length, look again.
I rigged this one up to make line A actually longer than B. You may have seen this puzzle a number of times before, and you may have hence concluded that although A seems to appear longer, it’s due to the fins playing tricks with my brain, and both are probably the same length as they usually are in this puzzle. Except, in this case, they are not.
Over years, we have trained our brain to not be fooled by this optical illusion, and we forego a careful consideration of what’s in front of us. To avoid the optical illusion, you became a victim of a cognitive illusion called confirmation bias: the tendency to interpret new evidence as confirmation of one’s existing beliefs or theories.
Having finally finished Daniel Kahneman’s Thinking Fast and Slow, I have started appreciating the critical role cognitive illusions play in our everyday lives! If you are looking for your next read, I cannot recommend this one enough.