Anchoring Effect

A famous and very common heuristic is called the ‘Anchoring effect’. This suggests that the first piece of information we get is weighed much more heavily in our decision making process than subsequent pieces of information – regardless of their actual relative importance. You might know this as ‘first impressions’.

A simple example is imagine you're shopping for a shirt, and you see one originally priced at $100, but it's on sale for $50. You might think it's a great deal because you're comparing the sale price to the original price. This is the anchoring effect. You're "anchored" to that first number you saw ($100) and use it as a reference point to judge the value of the sale price. Even if the shirt is not worth $50, you might still buy it because it seems like a big discount from the original price.

The anchoring effect is often taken advantage of as a dark pattern as the decoy effect by marketing agents.