Next time you grab a bag of oranges at the supermarket, take a closer look at the packaging. Chances are they are in a red net bag, and it turns out this bag is not just for convenience - it’s a clever trick to make the fruit look more appealing.

New research in the journal i-Perception finds that the red netting creates an optical illusion, making the oranges appear more vibrant and ripe than they might actually be. This in turn makes you think the oranges in a red bag are more ripe than the ones that are loose next to them, and so you might purchase more oranges than you had planned because they appear to be riper - even though they are exactly the same.

The technique is based on the confetti illusion, a visual phenomenon where a neutrally coloured object, such as a ball, appears to change colour based on the surrounding coloured patterns. In this illusion, when the ball is placed among an array of differently coloured lines, the colour of the ball assimilates to the colours of the lines, making it appear to take on hues that are not actually present in the ball itself.

When applied to oranges, the red net essentially enhances the orange colour, making the fruit look juicier and more enticing.

The same trick works for lemons too - and now you know the trick, you will notice they often come in yellow or green net bags as these have been found to intensify their natural colour.

So, next time you’re shopping and eyeing up the oranges and lemons, remember that colourful netting isn’t just a way to carry your fruit, it’s also a subtle way to trick your eyes and make you think you are selecting more ripe and juicy fruit than you actually are.

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