Principle #8: Reasons

28.03.2017 |

Episode #9 of the course Persuasion science masterclass: Part II by Andy Luttrell


Having reasons for your request can be all it takes to make your request more legitimate. If you see that someone has written an entire book arguing in favor of some position, you don’t even have to read the book. You think, “Well, whoever this is was able to fill hundreds of pages with their reasons for believing a certain thing. So just knowing that should be enough to tell me that there’s merit to what they’re saying!”

The “Social Rule”: When there’s a reason behind it, it’s legitimate.

The Principle of Influence: You can gain compliance by providing a reason (even a dumb one).

To see just how powerful a set of reasons can be, consider a mock jury study in which researchers had people witness a trial and then give their verdict (Calder, Insko, & Yandell, 1974). Crucially, either the prosecutor or the defense gave more arguments for their side of the trial. In the end, the verdicts were strongly influenced by whichever side simply provided more arguments. Sometimes that was the prosecutor and sometimes it was the defense.

But can it be that simple to persuade? To take advantage of this principle of influence, consider using the “Because” heuristic. According to this technique, providing any reason for your request increases the likelihood that someone says “yes.”

In a classic study (Langer, Blank, & Chanowitz, 1978), researchers interrupted people who were using a photocopier and asked them if they could cut in line and make photocopies before them. Sometimes, the person would simply make the request: “Excuse me. I’d like to cut in front of you so I can use the Xerox machine first.” That’s it.

Other times, though, the requester would add in a reason for asking. In one version, they would say, “Excuse me. May I use the Xerox machine because I’m in a rush?” That’s a decent reason for making this request! But in another version, they would say: “Excuse me. May I use the Xerox machine because I need to make some copies?” This reason is essentially meaningless. Obviously they need to make some copies! That’s why they’re in the copy room!

The question is whether including a reason improved persuasion and whether the type of reason mattered.

When the researcher made the basic request, simply asking to cut in line, people would agree about 60% of the time. But when they added a legitimate reason (“because I’m in a rush”), compliance shot through the roof. Now, 94% of the time, people agreed to let the person cut in line.

So what happens when someone just says, “Can I use the Xerox machine because I need to make some copies?” Even though it doesn’t offer any real information, compliance rates were 93%—no different than when the reason was legitimate. A replication study a few years ago (Key, Edlund, Sagarin, & Bizer, 2009) did exactly the same study as this original study and found exactly the same results.

The lesson is to simply justify whatever it is you’re asking from someone, even if it’s not that compelling. Importantly, though, this tends to only work when people aren’t paying very close attention. If the person is scrutinizing your question or if you’re asking for a very big favor, the meaningless reason doesn’t help. Nevertheless, when it’s an everyday small request, just adding a reason can be enough to increase your success rate.

Tomorrow we’ll wrap up this email course with the big-picture concepts of influence.


Recommended book

“Getting to Yes: Negotiating Agreement Without Giving In” by Roger Fisher, William L. Ury, Bruce Patton


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