21 Psychological Effects for Communication and Persuasion: From the Foot-in-the-Door Effect to the Zeigarnik Effect

Quick answer: - The 21 effects below come from a widely shared Zhihu compilation, translated into Vietnamese, valued for how directly they apply to everyday communication. - The persuasion group includes the foot-in-the-door effect, the forced-choice principle and the power of the word "because" when asking for help. - The people-reading group includes the silence effect, the mirroring effect, body language and the keyword-repetition rule. - The self-management group includes the 5-minute start method, the Zeigarnik effect and the principle of learning by teaching others. - Some effects on the list are documented in psychology research, while others are folk communication tips drawn from experience; treat them as heuristics to test, not absolute laws.

"Which psychological effects leave people in awe?" — that Zhihu question gathered a list of 21 applied psychological effects and tricks, translated into Vietnamese by Xi Xi and posted in the Weibo Việt Nam group. The list ranges from textbook psychology — the foot-in-the-door effect, prospect theory, the Zeigarnik effect — to everyday conversational tips such as looking at someone's nose when eye contact feels awkward.

What are applied psychological effects?

An applied psychological effect is a recurring pattern in how people perceive, judge and act, condensed into a ready-to-use tip for communication, persuasion, negotiation and self-management.

#	Effect	Core mechanism	Suggested use
1	Foot-in-the-door	Agreeing to a small request first raises agreement to a bigger one later	Ask in steps
2	Silence	Silence plus eye contact pressures people to tell the truth	Listening, interviews
3	Mirroring	Nodding and positive signals increase agreement	Presenting ideas
4	Forced choice	Choice questions instead of yes/no questions	Invitations, closing
5	Fixed action pattern	Adding a "because" reason raises compliance	Asking for help
6	Darkness	Dim light lowers unease and increases closeness	Dating
7	Pratfall / revealing flaws	Small flaws make an impressive person more likeable	Building goodwill
8	Suggestion	Modelling behavior and praising beats scolding	Management, parenting
9	5-minute start	Committing to 5 minutes defeats procrastination	Starting work
10	Expectation management	Modest starts with visible progress impress more	New employees
11	Body language	Feet direction, crossed legs and gaze reveal attitude	Reading people
12	Prospect theory	Segregate gains, combine losses when presenting	Negotiation
13	Zeigarnik	Unfinished tasks create an urge to complete them	Progress tracking
14	Learning pyramid	Teaching others is a top way to learn	Studying, training
15	Stockholm syndrome	Victims in unequal relationships cling to their harmers	Spotting toxic relationships
16	Bandwagon	A group's label shapes how others see you	Choosing your environment
17	Emotion management	Staying calm makes a humiliator the weaker party	Conflict
18	Opposite-sex effect	Mixed-gender activities tend to feel more fun	Organizing activities
19	Similarity	Shared views and hobbies create fast rapport	Building relationships
20	Repetition	Repeating the other person's keywords shows you are listening	Conversation
21	Projection	People attribute the adjectives you praise others with to you	Personal image

Which effects belong to the persuasion and asking group?

1. The foot-in-the-door effect. To get agreement to a relatively hard request, first ask for something small — borrowing a pen — then make the real request. Wanting to stay consistent with their self-image and "help through to the end", people are more likely to agree to the bigger ask.

4. The forced-choice principle. When you want someone to do something, do not ask a yes/no question; offer a choice: replace "Are you free this weekend?" with "Shall we go shopping or see a movie this weekend?". This lowers the chance of refusal and raises your success rate.

5. The fixed action pattern. When asking for help, attach a reason: hearing the word "because" — however trivial the reason — makes people default to assuming your request is justified. In most non-urgent situations, people are naturally willing to help to a degree; this is a built-in reaction of the brain.

Which effects belong to the listening and people-reading group?

2. The silence effect. To get someone to tell the truth, look into their eyes and stay silent. In the relative quiet, a person hiding something feels pressure and may unconsciously let the truth slip out.

3. The mirroring effect. When presenting your view, nod gently to send positive signals. Listeners gradually absorb your thinking without noticing, and their agreement grows stronger.

11. Using body language. Feet are among the most honest body parts: someone facing you while their feet point elsewhere usually wants to end the conversation; crossed legs while listening often signal incomplete agreement. A small tip for people shy about eye contact on a first meeting: look at the other person's nose — you appear to be looking straight at them while your brain stays relaxed.

20. The repetition rule. To make a good impression in a first conversation, repeat keywords from the other person's speech: they mention eggplant for dinner, you reply "Eggplant? Was it good?". Repeating shows attentive listening, and goodwill toward you grows.

Which effects belong to the goodwill and relationships group?

6. The darkness effect. In dim places, two people cannot read each other's emotions clearly, so unease drops significantly and sparks fly more easily. A dimly lit café is therefore said to be a better setting for a confession than a noisy eatery.

7. The flaw-revealing effect (pratfall). When buying a car, talk about the installment pressure and fuel prices; when promoted, talk about the heavy responsibility and late nights. Small flaws make you more likeable: people respect and envy the seemingly perfect, but prefer approaching the imperfect — and even feel sympathy for them.

16. The bandwagon effect. People label by group: returning overseas students are assumed fluent in English; top-university students are assumed smart. Conversely, joining a group of strong English speakers pushes you to learn English; being around readers makes you want to read more.

18. The opposite-sex effect. Psychology research notes an interesting phenomenon: activities with both men and women participating tend to feel more enjoyable than same-gender-only activities — the truth behind the saying "men and women working together never feel tired".

19. The closeness (similarity) effect. People naturally favor those who share their outlook and hobbies. Relationships often grow close quickly after discovering common interests or learning what the other person loves.

21. The projection effect. To build a good personal image, start by praising others. Through "spontaneous trait transference", listeners attribute the very adjectives you use — sincere, kind, smart — to you yourself.

Which effects belong to the self-management group?

8. The suggestion effect. To change someone's flaw, scolding works worse than modelling the behavior yourself and praising them when they get it right — people respond strongly to suggestions absorbed unconsciously. Before a speech, arrive 30 minutes early, walk the venue and stand on the podium so your brain familiarizes itself with the environment. When nervous, drinking water or chewing gum creates a sense of safety and calms the emotion.

9. The 5-minute start method. When you cannot focus, tell yourself "just 5 minutes". In most cases you will work far longer, because once the brain has started, focusing for another 10 or 20 minutes becomes easy. This method suits procrastinators well.

10. Expectation-threshold management. Young newcomers at work should keep their boss's expectations moderate: new hires who perform with excessive enthusiasm make superiors see fewer and fewer new bright spots in them over time, goodwill fades, and their own motivation drops with it. Those who start ordinarily but show clear progress from time to time leave a more positive impression. Still, the article stresses that every skill ranks below real ability — capability is the core competitiveness.

13. The Zeigarnik effect. Try drawing a circle and deliberately leaving a gap: your mind generates a strong urge to close it. People are driven to finish unfinished business; progress bars and percentage charts (say, 75.6%) exploit this psychology to push you through the remaining part.

14. The learning-pyramid principle. Teaching others is among the best ways to learn: knowing you must explain a problem forces you to express it concisely and clarify the key points, and the brain organizes the information more logically. Presenting and speaking in public regularly is how you practice this principle.

17. The emotion-management principle. When someone tries to embarrass you, staying calm is the most effective weapon: your politeness quickly makes the other party the weaker side, even a laughing stock, while losing your temper is exactly what they wanted.

Which effects belong to the negotiation and boundaries group?

12. Applying prospect theory. In negotiation, segregate the gains and combine the losses: present each benefit one by one, but state all the losses in a single go. In the article's birthday example, good news ("I bought you a cake") followed by two pieces of bad news crashes the mood shock by shock, while bad news first followed by successive good news leaves the overall feeling that "the gains outweigh the losses".

15. Stockholm syndrome. In unequal intimate relationships, many people endure emotional abuse, cold violence and verbal attacks, yet cling to the few small joys to return to the person who hurts them — "he hits me, but he loves me". The original draws a practical warning: do not step in to mediate other people's family conflicts on your own, because in the end you may well be the one who gets hurt. Read positively, this is a warning sign for recognizing a toxic relationship.

Frequently asked questions

What is the foot-in-the-door effect?

It is the phenomenon where a person who has agreed to a small request becomes more likely to agree to a larger one from the same person, because they want to act consistently with the helpful self-image they have just displayed.

What is the Zeigarnik effect?

It is the psychological tendency to remember and feel driven by unfinished tasks more strongly than completed ones. Practical uses include progress bars, half-ticked checklists and percentage goals that create motivation to finish the rest.

Why does adding "because" when asking for help work?

Per the compilation, people react almost automatically to the structure "request + reason": hearing "because" makes the brain default to treating the request as justified, even when the reason is tiny. The list names this the fixed action pattern.

How is prospect theory applied in negotiation?

Per this list: segregate gains, combine losses. Present each benefit separately so the other side feels multiple "wins", and bundle all losses into a single presentation so the pain of "losing" is felt only once.

How reliable is this list of 21 effects?

It is a popular compilation from Zhihu, not an academic source. Some entries are psychological effects documented widely (foot-in-the-door, Zeigarnik, prospect theory, bandwagon), while others are communication tips drawn from community experience and personal observation. The sensible way to use them is as suggestions to try and verify in your own communication.

Source: the article "[ZHIHU] Which psychological effects leave people in awe?", originally on Zhihu (question no. 20357247), Vietnamese translation by Xi Xi, posted in the Weibo Việt Nam group on Facebook on November 3, 2026.