Only eagle-eyed Brits can spot cheating man in just 5 seconds

Put your visual skills to the test with this sneaky brainteaser that leaves most people scratching their heads. Solving puzzles and riddlesmay seem like a pointless pastime, but it's actually a great form of mental exercise. No, it won't boost your IQ and help you get into Oxford, or land you with a Mensa membership - but research has suggested it could help better your attention span and improve your concentration skills.

Created by ARF Private Investigators, this deceptively difficult brainteasercan only be solved by those with a high IQ and razor-sharp attention to detail. While most people take an average of 15 seconds to spot the key difference, just one in 10 can solve it in under five. So, what are you waiting for?

READ MORE: You're a genius if you can solve baffling maths question in just 5 seconds

The two images above may seem perfectly innocent at first glance. They just show a regular guy sending a selfie to his wife, who is currently away on business.

However, there's a subtle clue hiding in plain sight that reveals that one of the men is actually cheating on his partner. You need to find the adulterer in just five seconds or less to prove you have eagle eyes - so set your timer and get searching!

We're not giving away any clues for this one, but if the time limit is a little too intense - ignore the buzzing timer and take as long as you need to solve it. Still feeling stumped, or reckon you've finally cracked it? Scroll down to the bottom of the article to find the answer.

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If that adulterous-themed brainteaser was no match for a smarty pants like yourself - it's time to take on your next challenge. Below is a riddle that might seem easy at first - but will send you into a complete spiral when the answer slips your mind.

"I have keys but no locks. I have space but no room. You can enter, but you can't go inside," the riddle reads. "What am I?"

You have just 12 seconds to lock your answer in and prove that you're a modern-day genius. Fail, and you can kiss your chances of becoming the next Albert Einstein goodbye.

Again, we're not giving away any clues on this one but you don't have to follow the 12-second rule if you really want to take your time solving the riddle. Once you are done, you can check your answer here - but no cheating!

ANSWER: Check out the glass on the kitchen table. There is a slight lipstick smudge, that shows that someone else is close by.

Up for another mental workout? Check out our full collection of tricky brainteasers, riddles, and puzzles here - or, learn more about your hidden personality traits with these mind-boggling optical illusions.

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