Researchers who study animal behaviour have documented the fact that many species react in pre-defined ways to various stimuli. For example, a bird will protect even a predator if it emits a taped recording of a chirping sound normally made by a baby bird.
This trigger and automatic response that disregards all other factors can be valuable, as it allows animals to make decisions quickly, without having to analyze a plethora of information, some of which is undoubtedly irrelevant. On the other hand, it can also result in costly mistakes, since only one piece of information is used in driving behaviour.
An example where humans apply this type of behaviour has to do with how people determine the value of various items (stocks, objects etc.): by basing its perceived value on its price. This method of value determination does have its advantages: if every time a new object was considered for purchase, humans researched it and studied it extensively, there would be little time for anything else. On the other hand, this can lead to foolish decisions in the cases where price and value are not matched properly.
Marketers and salespeople who understand these shortcuts humans have developed to expedite decision-making can profit by triggering the human responses they desire by arranging the appropriate stimuli to their advantage.