Framing effect

How you say matters more than what you say even when both have the same meaning. There’s a hell lot of difference in how people will react when you say there is a 90% chance you will survive this operation, don’t worry vs but there is a 10% chance you will die from this operation, so, are you up for this?
Advertisers often use this to their advantage. The commonly referred example is the frozen yogurt one. The 20% fat yogurt is shown as 80% fat-free. It is simply the old adage glass half-full, glass half-empty, branded intellectually.
Often it is used along with anchoring bias. 50$ on a t-shirt is struck off and sold for 35$, and we never question the fact of whether does it have the value of 50$ in the first place. And
If possible, always stick to the positive frame and avoid the negative one, as humans have loss aversion in them inherently.
By the way, 399$ price tag works over 400$ price tag.