A clever trick you fall for every time you buy oranges at a supermarket

If you’re a cynical shopper – and who isn’t? – then you’re already aware of various supermarket ploys for getting you to spend more, potentially on things you weren’t interested in buying in the first place.

Shelves are carefully coordinated so that your eyes are drawn to certain products, or so your kids are more likely to spot something and nag you about it.

They even pump particular aromas into the air to get you in the mood to buy fresh bread, among other things.

Of course, the tricks of the trade don’t stop there, and there’s a particularly interesting one being used for oranges.

"What if I told you that the red nets the oranges are packed in are part of a brilliant marketing trick played on you?" asks Pranav Joshi in a video posted to his Instagram account, @floydiancookery.

There are all kinds of marketing tricks being used at stores like Tesco - Matt Cardy via Getty Images

"We don't really see colours with our eyes as much as we do with our brains," he explains.

Here he’s talking about a phenomenon called Colour Constancy, whereby the same colour can look different depending on the other colours around it or the lighting it’s under.

Pranav uses the black-blue or yellow-gold dress that went viral several years back as an example, with different people reporting seeing different colours on their devices.

There’s no potential for digital trickery going on when it comes to supermarket oranges, of course.

The variability in colour perception was first theorised by Wilhelm Von Bezold, German physicist and meteorologist, Pranav continues.

"He found out that the colours we see are understood by our brain in relation to their surroundings. Now this becomes even more interesting when different colours interact with each other."

To demonstrate what’s going on, he takes two oranges of the same colour and covers them with a striped grid. You can see that the oranges’ colour changes depending on the stripes laid over them, and it’s this effect being employed by supermarkets with their red netting.

It’s called the Munker White Illusion: the foreground colours draws the background colour closer to it. When red is laid over orange, the orange comes closer to the red and looks more vibrant.

The same trick is used with green netting over lemons.

Now you know, it’s the kind of thing you might notice with other products.

If you’re wondering why supermarkets bother, it’s all about making the food look fresher and more appealing. No pun intended.

You'll never trust an orange again - View Pictures via Getty Images

"OMG I love learning this! And what a great metaphor twist at the end!" said one Instragram comment on the video.

"Nice info!" said another, while yet another added: "This is incredible."

Some were curiously riled up by the video, however.

"You really think that street vendors put so much thought into packing?" said one person who seems to have missed the point of the video.

"The red nets are a health hazard, they shed tiny fragments of red plastic that can get into food unnoticed especially since even tomatoes are packed in these nets,” said another. “Should be banned."

It’s recommended that you give fruit and veg a wash before eating it, of course, regardless of how it’s packaged.

• Jeremy Clarkson's Diddly Squat farm produce now available at major supermarket
• Expert shares clever trick to check your fridge is working properly
• Clever 'two-finger rule' you should always follow when buying a watermelon
• Experts share 3 warning signs you need to urgently replace your cookware