When making decisions, we start from so-called “anchor”, which the first known piece of information. Numbers and prices, especially in advertising, are very good examples of anchors.
The story from N: “They had burger on the menu with this message: “No more than 6 types of cheese in the burger.” My first thought was: who will order 6 types of cheese in a burger? My second thought was: which 6 should I choose?”
Of course, most people will not take 6 types of cheese, but this anchor is enough to choose more than one type of cheese.
Strangely enough, even mentioning of a completely random number, our thinking can be affected. Examples of anchors:
– prices of several pieces of the product (even if there is no volume discount)
– limitations (no more than X pieces)
– any number (buy 18 “snickers”)
Charitable organizations also use this effect when sending letters with proposals to make donations. Larger amounts in letters make people donate more, comparing to smaller amounts in similar letters. Even if the text copy of the letters is the same.