New Delhi, Nov. 3 -- Rs.1,000 is not always Rs.1,000.At least, not to your brain.

When you hand over a crisp Rs.1,000 note, your brain winces. There's a small sting, a flicker of regret. But when you scan a QR code or double-tap to pay on UPI, the pain almost vanishes. It feels painless, frictionless, even satisfying.

Let's unpack what's going on under the hood.

Researchers at Carnegie Mellon and Stanford found that spending money activates the same brain regions linked to physical pain. That's why you feel a twinge when you hand over cash; it's not just emotional, it's neurological.

Cash creates salience; you physically see it leave your hand, your wallet gets lighter, and your brain connects the dots: loss has occurred.

Digital pay...