Optical Illusion: Can You Find the Hidden 81 Among the 87s?

Look closely at the grid below. At first glance, all the numbers appear identical. However, there's an 81 somewhere in between all those 87s. It takes most people more than 15 seconds to find the number out. Can you beat that?

Can You Spot the Hidden 81?

Here’s your challenge. Somewhere in the grid below, one number reads 81 instead of 87. The rest are all 87s.

Can you spot it?

Set a timer. See how long it takes you to find it.

Take a good look before reading on. The answer is provided at the end of the article.

Why Is This So Hard to See?

Your brain is not lazy. It is actually too efficient for its own good.

Your visual system is immediately aware of the repetition of the pattern when you scan a grid like this. After it has learned the pattern "87 87 87", it begins to guess the next number. This allows your eyes to scan without your brain processing the information.

This is known as visual pattern habituation. The brain has the ability to decrease its response to repeated stimuli over time according to the research published in the journal Vision Research. Simply put, your brain pays less attention to what it sees more and more.

The numbers 8 and 8 have the same starting digit and your brain groups them together. The only difference is the second digit, 7 and 1. The numeral 1 is narrow and simple and does not make a strong contrast with the surrounding 7s. This makes the 81 much more difficult to spot with a quick glance.

Jeremy Wolfe, PhD, a neuroscientist at Harvard Medical School, has been studying this type of visual search for decades. His research reveals that the closer the target is to its background, the more time will be required to spot it. This puzzle is an excellent example of this effect.

Did You Spot the Number 81?

Still stuck? The answer might surprise you.

The 81 is in row 8, column 3.

Count down from the 3rd column in the 8th row. That's where the 81 is hiding.

If you did, your visual attention skills is top notch. Most people look at the top rows and right side of the grid first, making it all the more surprising when it's placed lower and to the left.

One secret that always works: Instead of reading each number, just read the second number. Look only for 1's down each column. That way, your eye will be drawn to it that much quicker.

In our informal trials, most readers are able to locate the hidden number within 10-30 seconds. 10 seconds or less is pretty quick. If you look at things row by row without a focused strategy, you will take more than 45 seconds. If it took some time, don't worry. The puzzle is intended to be challenging.

What Your Search Style Might Say About You

There is no definitive science linking your search style with personality traits. But puzzle researchers have noted a few interesting patterns in how people approach visual search tasks.

If you started from the top-left and moved right, you tend to approach problems in a structured, methodical way. If you jumped around the grid, looking at random spots, you may rely more on intuition. Neither approach is better. The structured scanner often finds the answer with fewer total eye movements. The intuitive scanner sometimes gets lucky much faster.

Keep in mind this is just for fun. It is not a clinical test of any kind.

Now that you know the trick, try scanning the grid a second time without looking at the answer. You will find it much faster this time. That speed boost is your brain updating its search pattern. This is the same learning mechanism that helps people spot errors in proofreading after they know what to look for.

Share this puzzle with a friend and see who finds the 81 first. They will not find it as fast as you did.

Also, check out other interesting puzzle challenges in the Puzzles and IQ test section. Stay connected with Jagran Josh for more such informative and interesting articles.

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