There are two very important researchers who have written extensively about this: Robert Cialdini (an expert in the psychology of persuasion), and Daniel Kahneman (an expert in the psychology of cognitive biases).
I highly recommend that everyone be familiar with Cialdini's work, because it relates to making good decisions in the modern world. Cialdini has spent decades studying the persuasive techniques which are used in sales and marketing, with the rigorous and thoughtful eye of a scientist and experimental social psychologist. A problem with Cialdini, however, is that his books seem too focused on an audience of business people and marketers.
Kahneman: Cognitive Biases
Kahneman's work focuses more on the cognitive mechanisms that affect judgment, and this area is an important complement to Cialdini. Kahneman is the only psychologist to have won the Nobel prize! His psychological work is very relevant to economics--it is a quantitative look at how human cognitive biases affect all decision making, including small and large economic or financial decisions.
Why is this Important?
Cialdini -- and probably Kahneman too -- are most appreciated by people in the business community, especially marketers, since their ideas are likely to help any business earn more profit. But I think these ideas should be part of everyone's knowledge base, since they will help us all to protect ourselves from being influenced by marketing in an unwelcome way. Not just obvious marketing, such as commercial advertising, but also subtler forms of "marketing," such as experiencing persuasive forces in the workplace, in the media, in politics, and even in our personal or social lives.
In his initial work, Cialdini described 6 factors contributing to persuasion:
1) Reciprocity. If someone gives you something, you will be more apt to give something back, including your approval or support! If you are treated to lunch, you will be more likely to comply with someone's request afterwards! This is a normal, natural thing, and even part of good social skills...but be careful about this, because sometimes the person giving you a free lunch may have an agenda to change your mind about something that you would otherwise not want to change. A very troubling example of this in current events is of extremist groups providing free food, shelter, and other care to people in need...while helping people in need is wonderful, it also leads the people receiving this help to be more likely to join the extremist group! We can address this problem politically by making a big effort to help people in need long before an extremist group does, rather than focusing only on military solutions to such problems!
2) Consistency. Once you have done a certain action, or agreed to a certain thing, or committed in a small way to a certain thing, you are more likely to go further with that same thing in the future. If you once joined a particular political party, you will be much more likely to keep supporting it in the future, even if you would otherwise disagree. If your parents and grandparents have always supported a certain political or religious group, you will be more likely to also support the same group, since it could seem inconsistent, or even a "betrayal," to change your mind or your actions. This consistency can be a great thing--it is part of maintaining a personal or community culture. But it can also cause people to be "stuck" with ideas or behaviours which are unhealthy or harmful, yet with a resistance to change. Marketers use this phenomenon all the time, by encouraging you to become a "member" of a points plan for a particular business, to have consumer "loyalty" programs, by having you formally endorse one of their products, which leads to a long-term tendency to choose the same products again.
Be careful about this one! Consistency is good, but not if it prevents us from changing our mind when change is needed. Some of the most disastrous events in world history happened when people's consistency and commitment led them down a dark path...
3) Social Pressure, or Social Proof. If you see that something is becoming more popular, you are more apt to support it. Suppose you are starving in the woods, and you see bushes with berries on them. You are not sure whether they are poisonous or safe. If you see other people happily eating those same berries, you will obviously be reassured that they are safe, and you will happily pick some berries for yourself! In this case, social proof is very useful and protective. But marketers routinely use information about social proof to push us to support things or buy things. Even the polls that we see in the media can have this effect: if someone claims that a particular candidate is soaring in popularity, many people will be more likely to join in and support that person as well. This effect is especially pronounced if the social proof comes from people who are similar to us in some way. For example, if you are shown that most people who are around your age, and who come from a similar ethnic background, and who share similar cultural interests, are all supporting a particular political candidate, you will be more likely to be persuaded to support this candidate as well.
Once again, this is a normal and often efficient way to make decisions in life, by assessing the decisions that similar people are making already. It is what Kahneman calls a "cognitive short-cut."
But marketers use this factor all the time, to push us to support things, or to buy things, that we otherwise would not want.
4) Liking. If someone you really like asks you to do something, or to change your mind, you are more likely to comply! This is again a completely normal, understandable, and often useful human behaviour. But be careful with this one! Marketers, politicians, and even people in your social circle could sometimes push you to make decisions you otherwise would not make, just by being nice, and by being "likeable." The stereotype of a "con man" usually includes being physically attractive, charming, and superficially likeable. Be careful not to let these factors affect your judgment more than you want!
5) Authority. This is a huge factor, both in the marketplace and in a professional work environment. It is another very useful cognitive short-cut to assume that an "expert" has good advice. Often the expert or authority (such as a famous doctor or researcher) really does have useful advice and wisdom! But people are easily prone to shutting off their critical judgment if they are told something by an expert. In many cases, an expert may have a particular agenda for change which is not directly related to their expertise. And in many cases, a speaker may be granted more "authority" or expert status than is reasonably warranted. For example, it is a tradition for speakers at a meeting or conference to be introduced with a glowing biographical vignette, summarizing a list of very impressive credentials, degrees, awards, and a publication record. These facts may be completely accurate, but it is important to know that this introduction will increase the speaker's persuasive influence over the audience...While this is often useful and reasonable, it could also often give the speaker license to influence the audience about all sorts of things that are outside of their expertise!
I have seen this in my work very often: a speaker with impressive credentials is greatly respected by the audience. The speaker's ideas about treatment strategies (e.g. medication or therapy approaches for treating depression) or about health care policy (e.g. how to set up an efficient medical system) are accepted by the audience in a much more uncritical way, with much less reasoned debate, than would be the case if the same ideas were shared without the introductory eulogy about credentials!
Be careful when you see a commercial featuring an esteemed expert or authority endorsing a product. The information you hear should be considered seriously, but remind yourself that you may exaggerate the validity of this information, simply because you respect the expert's authority. Always question authority! Don't reject it outright, but always question it!
6) Scarcity. If you know that something is rare, or disappearing, you are more likely to desire it more. This factor is routinely used in sales and marketing: if a particular product is "disappearing fast," or if you are told it is your "last chance" then you are more likely to be interested in it. If you are guided to believe that you have some kind of rare, special, personalized knowledge about something, then you are more likely to act on it.
In marketing and politics, the fear of loss can have an exaggerated influence on people's decision making. The fear of loss of security or safety can lead to a greatly increased focus on policies addressing this (e.g. military or policing issues). While it is reasonable to focus on such things, ironically the fear involved can distract attention away from other policy factors which would ultimately have a much better chance of improving safety (such as enhancing diplomacy, improving education, focusing resources on eliminating poverty, etc.)
In Cialdini's more recent work, we could add another factor, one which Kahneman has talked about extensively as well. It is something which all the other 6 factors incorporate to some degree as well:
7) Guided Attention & the Focusing Illusion
If our attention is guided towards something, we are much more likely to assume that this thing is important, and that it has some causal influence. A magician or illusionist routinely makes use of this...most magic tricks involve carefully guided attention, so that we don't notice the magician fooling us, right in front of our eyes! I encourage you to look at some YouTube videos showing clever illusionists using this phenomenon; here's a good example: https://www.youtube.com/watch?v=GZGY0wPAnus
This factor is arguably the most powerful of all persuasive influences. When a person or a group is focusing on something, we will be guided into thinking that this focus is more important and causal than it really is, and it will prevent the person or group from asking other important questions!
Cialdini gives a good example of this, having to do with the journalists who were allowed to cover a recent war. The journalists were given unique, unprecedented "embedded" access to soldiers in their daily lives. On the one hand, this allowed a valuable transparency about the goings on in the war. It led to a focus upon the daily dramas in the life of a soldier: the harsh climate, the food, the camaraderie and bonding with fellow soldiers, and especially the heroism, bravery, and self-sacrifice involved in the battles. As a result of this focus, the viewers would form an understandable and healthy attachment to the human stories on the battleground, and would form a completely normal and healthy admiration for the bravery and nobility of the soldiers. But--because of this, the viewer would be less likely to question the strategy of the war itself!
The manner in which a story is focused upon can distract us from asking other questions about the story, which may need to be asked!
In a work environment, there could be a new policy scheme, which in some ways could be similar to the example above...it could involve honourable, devoted, intensive efforts from many warm-hearted people, all of whom nobly striving towards making things better. But once such a plan is in action, the attention of the group becomes focused upon the daily "battles" and human dramas associated with enacting the plan. The group is much less likely to question the strategy of the plan itself, even if the plan is unhealthy or harmful.
One can see this in political movements: supporters of a particular political party or candidate are working very hard, are forming strong social and emotional bonds with the cause...they are motivated honourably, often with strong wishes to make the country better. There are daily struggles with polls, with debates, with interviews, with criticisms from opponents...these struggles are analogous to a battlefield. The stories involved with the battles are dramatic and engaging, and the media on both sides of the battle are eager to focus on them. But because of this, supporters are likely to simply focus on continuing the battle they started, rather than pausing, reflecting, thinking deeply, and being willing to change their strategy or beliefs if necessary and morally right.
So, this is what I mean by "GroupThink." It is going along with what other people are thinking...due to reciprocity, consistency, social pressure, liking, authority, and the focusing illusion...we then risk getting caught up in things that aren't good for us.
"GroupThink" can often be efficient, to get certain tasks done. If everyone in a group is constantly stopping, reflecting, and questioning themselves, then the group's actions could be frozen...but we must always at least be aware of how powerful "GroupThink" is, and how it affects all of us. The antidote for this, the way to keep this force balanced, is to always be willing to question things!
Be willing to question others, even authorities, even people whom you really like! Be willing to question yourself! Just because you have thought, felt, or done a certain thing for a long time doesn't mean you can't change your mind, your feelings, or your actions!
Be aware that there are powerful persuasive factors in our lives, all around us...we don't have to be afraid of them, but we do need to know that it can be easy to follow these factors passively. We can live healthier, happier, more satisfying lives if we take some time to step back, think carefully about our decisions, and be willing to speak up!