There are sayings in many languages of the world that illustrate the human tendency to escalate demands. The Americans and British say “give them an inch, they'll take a mile.” Germans and Poles say “give someone a finger, they'll take your whole hand.” Hungarians and Spaniards phrase it like this: “If you give someone your hand, they'll take the entire arm.” In all cases, the idea is the same: If you give people something small, they will immediately ask for something bigger. These sayings describe the typical behavior of people with a sense of entitlement. From the perspective of social influence, however, what is more important is not so much the escalation of demands by people who are offered something, but rather the effectiveness of their actions. We are thus interested not in those who ask for something, but in those who are asked for it. Indeed, the question arises: does the fulfillment of an easy request make people subsequently more willing to fulfill another, clearly more difficult request? Returning to the metaphors cited above, if we assume that we are unlikely to want to give up an entire mile to someone, the question is whether we are significantly more likely to do so when someone employs the following strategy on us: first they ask us for an inch, and only after we give it to them do they ask for a mile. Social psychology calls this technique “foot-in-the-door.” If you want to enter someone's house and you think it will be difficult, try to get them to open the door for you first.

Imagine that you have a house in California, located along a busy road. Someone explains to you that a campaign is being organized to improve road safety. Billboards are being installed along the roadside urging people to drive carefully. Your lawn would be perfect for such a billboard, but they don't offer you any money for it; in addition, your property will suffer esthetically. Would you consent? Jonathan Freedman and Scott Fraser (1966) established that roughly 17% of people say “yes” in such a situation. We can thus characterize this request as difficult, and certainly quite exceptionally agreed to. Would the percentage of people agreeing to install a billboard increase if we first asked them to comply with a request that was clearly easier? Randomly selected individuals were visited by a man who formulated a simple request. Namely, they were asked to sign a petition to the governor of the state of California. In one case, it was a plea for boosting efforts to keep California clean; in another, it was for increased attention to road safety. Still, other respondents were asked to affix a small sticker to the corner of a car window or windshield. In one case it was an appeal to keep things clean, while in others to drive carefully. Of course, nearly everyone complied with the small request. When they were visited two weeks later by a man asking for permission to install a billboard, they agreed to the request significantly more often than did people who were asked to do so immediately. Keep in mind that when such a request was made straight away (that is, to use the language of the experimenters, in the control conditions), less than 17% of those approached agreed to the billboard. This time, nearly half of those who had previously signed some sort of petition or affixed a “Keep California clean” sticker agreed to the billboard. And in conditions where two weeks earlier people had put up a sticker appealing for careful driving, the proportion was as high as 76%! Thus, we see that the foot-in-the-door technique proved effective. Those who were first asked to comply with an easy request were then more likely to comply with another, clearly more difficult one, than those who were simply given the difficult request right away. There is still the question of why Freedman and Fraser tested in their experiment the consequences of people fulfilling as many as four different easy requests. Note that the difficult request, the one actually in question, concerned consenting to the presence of visual propaganda (billboard) about traffic safety. In two cases, the content of the first request was also about careful driving; in two others, it was about keeping California clean. Regardless, in two cases, the first request, like the second one, concerned visual propaganda (“put a sticker on it”), while in two others it was of a different character (“sign a petition”). The authors of the study wanted to see whether both requests had to be very similar (both in form and content) for the foot-in-the-door technique to be effective. This turned out to be unnecessary; it was enough that both subsequent requests “had something in common.” In this case, it was engaging in a good cause to help others. At the same time, however, the technique proved to be by far the most effective in conditions of high similarity between the two requests.

Probably everyone knows that when women are unhappy, they sometimes start crying. Our beliefs, judgments about the world, views, mental states affect our behavior. But social psychologists say something else: sometimes, if women start crying, they then come to the conclusion that they are unhappy. Our behaviors can influence our beliefs and views. Why does someone who complies with the first request agree to fulfill a subsequent request? Freedman and Fraser hypothesized that humans reflect not only on what they should do but also on what they have already done. We also ask ourselves (not necessarily in a fully conscious way) why we agreed to fulfill a request. We first look for external causes. Did someone force us to do this, blackmail us? Not at all! Or maybe someone paid us a tidy sum of money? Nope! So, why did we agree? We ourselves come to the conclusion that we are “the kind of people who do such things.” (In reference to the experiment described above: people who act to benefit the Californian community). If we begin to think of ourselves this way… we should then behave according to the belief we have just formed about ourselves. People who are committed to the well-being of residents of their state and think it is the right thing to do should agree to hosting a billboard that may reduce traffic accidents. Another interpretation of the effectiveness of the foot-in-the-door technique referenced by social influence researchers points out that our culture values consistency. If you said A, then say B; if you started something, finish in. So, if you've done something, and now someone's asking you to do something similar, then… do it, of course.

If fulfilling an easy request then leads people to fulfill another request, perhaps the effect would be even stronger if people were initially asked to fulfill not one small request, but several? After all, in that case, there would be both more reason to think of oneself in terms of “I am a person who fulfills requests of this kind” and to show consistency in one's own behavior. Would you lend a friend a dollar? Maybe you would, maybe not… It would probably be easier for you to reach for your wallet if the person asking you had already once borrowed a hundred dollars, then paid you back the next day. But perhaps you would agree to lend someone money even more easily if you had already lent that person money several times and always got it back the next day. While the technique we presented previously was called foot-in-the-door, this time we should talk about feet-in-the-door or even multiple feet-in-the-door.

Nicolas Gueguen, Fabien Silone, and Mathieu David (2016) set out to see if the technique discussed here could be used to get people to stop smoking cigarettes. They focused on the conditions under which smokers would agree not to use tobacco for 24 hours. (A day without a cigarette is a trivial thing for non-smokers, but a real challenge for smokers.) In the control condition, participants were simply asked to refrain from smoking for 24 hours. The rationale for this was that the researchers were interested in learning about the impressions of smokers who quit for a while. The effectiveness of the now-familiar foot-in-the-door technique was tested in two different conditions. In the first, participants were asked to complete a short survey about their addiction. They responded to questions about their favorite brand of cigarettes, how long they had been smoking, whether their parents smoked, and whether they had ever tried to quit. They were then asked to abstain from smoking for 24 hours. In another condition, participants were first asked to refrain from smoking for two hours, and after a period of time, a request to refrain from smoking for 24 hours was made. In the two-feet-in-the-door condition, the participants were first asked to complete the aforementioned questionnaire, then to abstain from smoking for two hours, and only finally to abstain from smoking for a full 24 hours. In all the conditions of this experiment, the researchers first recorded whether the participants agreed to 24 hours of nicotine abstinence and then asked them if they managed to keep their word. The foot-in-the-door technique proved to be effective. While in the control condition, where participants were immediately asked to abstain from smoking for 24 hours, only about 27% of those questioned said they would do so and only about 12% said they actually managed to keep their word, both of these numbers were higher when participants first complied with the easy request. If they completed a short survey, 41.5% of the participants agreed to 24 hours of nicotine abstinence, and almost 21% declared post factum that they had not smoked for 24 hours. If the initial request was to abstain from smoking for two hours, both of these rates were even slightly higher (nearly 63% and nearly 28%, respectively). However, the effect was by far the best in the conditions in which participants first completed a survey, then abstained from smoking for two hours, and finally were asked to attempt 24-hour abstinence. In this situation, as many as 93% agreed to abstain from smoking for 24 hours, and 46.5% declared that they had not smoked a single cigarette for 24 hours!

The two-feet-in-the-door technique is an extension of the foot-in-the-door technique. We can also easily imagine even more complex forms of such interaction. The final request would then be preceded not by two clearly easier requests (as in the study described above), but three, four, or even more. Of course, it is assumed that the psychological mechanism underlying this technique is analogous to the technique in which only one easy request precedes the formulation of the final request. However, the more requests there are in the sequence, the factor inducing the participant to fulfill the final, difficult request should be stronger and act more strongly. The results presented above, as well as those of many other psychological studies, indicate that this is indeed the case.

Robert Cialdini and Brad Sagarin (2005) noted that people's inclination toward consistent behavior is often exploited by door-to-door sellers. Before such salespeople offer to sell “a great set of vitamins and trace elements,” they have a short chat with the customer. They first ask their customer if health is important. Then, they ask whether it's worth taking care of one's health. Another question goes “Is it better to prevent diseases than to cure them?” All of these, after all, are rhetorical questions. The person being asked will answer “yes,” “yes,” “of course,” “yes.” And only now do they offer a sensational substance capable of preventing almost all diseases and ailments. How can people who have clearly and unambiguously declared that health is a very important consideration for them not buy this incredible product?

A group of French psychologists – Nicolas Gueguen, Robert-Vincent Joule, Didier Courbet, Severine Halmi-Falkowicz, and Marie Marchand (2013) conducted a study that ostensibly was merely about the foot-in-the-door technique. It was a field study, and the participants were unsuspecting passersby. In the control conditions, they were asked if they would agree to fill out a rather long survey consisting of 45 questions. Of course, they could do it at home, and if they agreed, they would receive a stamped envelope into which they would put their responses after completing the questionnaire and send it back to the researchers. A total of 30% of the participants agreed to do so. In other conditions of this experiment, before participants were asked to take home a long questionnaire, they were asked a few questions. We know what this is, right? Foot-in-the door! Were those who first answered a few questions then more likely to agree to complete a long survey? Yes, this was indeed the case. But from the perspective of the technique, we are now presenting, the key point is how these initial questions were formulated. As it is, half of the time they were worded so that the obvious answer was almost always “yes” (e.g., “Have you ever assembled a storage unit?”), and the other half of the time so that respondents almost always answered in the negative (e.g., “Have you ever installed a solar water heater?”). It turned out that if the respondent answered in the negative several times within this short field survey, the percentage of people who agreed to take the long survey doubled, reaching 60%. But if the questions of the survey were formulated in such a way that the respondent said “yes” several times, the rate reached a skyrocketing 83%!

Four walls is a technique in which the interlocutor is induced to make statements that lead toward a consistency trap. Failure to accept the offer will constitute incorrect and inconsistent behavior. In fact, one could say that it would make the interlocutor a hypocrite. The French researchers have demonstrated that merely saying the word “yes” can cause an impact. When “yes” is repeated several times, the general tendency to agree and approve increases. This is because in many situations people function with little reflection and quite automatically. People who have in a fashion set themselves up to agree by saying “yes” to several statements are more likely to also agree to the next one than people who have set themselves up to disagree by responding “no” several times over. From this perspective, it is plausible to think that although salespeople might trick their interlocutors into a consistency trap by asking a series of questions that will be answered negatively (e.g., “Is it healthy to eat a huge amount of sweets instead of vitamins?”), more effective salespeople ask questions that evoke affirmative responses.

In the case of the four walls technique we discussed earlier, the interviewee is initially asked a series of questions. The person's positive answers to these questions then make them more willing to comply with the request. The request is consistent with the content of the answers the person has just given. But what if, before asking us for something, someone uses a general and “smooth” statement like “Could you do me a favor?” or “Could you do me a service?”. Unless we are tired, upset, or in a hurry, we are unlikely to say “no.” Most probably we will either react normally, simply responding “yes,” or we will answer a little more carefully, using the phrase “it depends.” So if we answer “yes,” we will not really be able to refuse the request that will appear in a moment (especially if it proves not too difficult to fulfill). If we answer “it depends,” then probably… it depends. Depending on the nature of the request, we will accept or refuse it. As for the people who reject the question “Could you do me a favor/service?”, they would probably also refuse a directly formulated request. So it would seem that preceding the request with the phrase we are talking about here may clearly increase the chances of its fulfillment. Is this really the case? Let us take a look at the results of a simple experiment.

The study conducted by Sebastien Meineri, Michael Dupre, Boris Vallee, and Nicolas Gueguen (2015) was carried out in France, in a mid-sized city. It was conducted alte...