Marketing · 4 min read
8 Psychology Studies Growth Marketers Cite (and Their Limits)
Short answer
Studies often cited in growth marketing include the mere-exposure effect, the jam study on choice overload, the foot-in-the-door technique, the IKEA effect, the endowed progress effect and the decoy effect; several are solid, but some, like choice overload, have mixed replication results.
Key takeaways
- Read what a study actually tested before borrowing its conclusion.
- Choice overload is real in some settings and absent in others; meta-analyses find mixed effects.
- Use these ideas to design tests, not to skip testing.
- Persuasion techniques that mislead people backfire and may break consumer protection rules.
Growth marketing borrows heavily from psychology, and a handful of studies get cited in almost every slide deck. Some hold up well. Some have been complicated by later research. Here are eight, with what was actually tested and how to use each one honestly.
Which studies come up most often?
These eight appear again and again in marketing advice.
| Effect | Study | Finding in one line |
|---|---|---|
| Mere exposure | Zajonc, 1968 | Repeated exposure tends to increase liking |
| Foot in the door | Freedman & Fraser, 1966 | Agreeing to a small request makes a larger one more likely |
| Decoy effect | Huber, Payne & Puto, 1982 | A clearly worse third option shifts choices between the other two |
| Choice overload | Iyengar & Lepper, 2000 | More options attracted shoppers but fewer bought |
| Endowed progress | Nunes & Drèze, 2006 | People given a head start on a goal are more likely to finish |
| IKEA effect | Norton, Mochon & Ariely, 2012 | Effort put into making something raises how much people value it |
| Zeigarnik effect | Zeigarnik, 1927 | Interrupted tasks are often remembered better than finished ones |
| Social proof | Cialdini and others | People look to others' behavior when unsure what to do |
What did each one actually test?
The details matter, because they limit where the finding applies.
Mere exposure. Zajonc showed people unfamiliar words, shapes and faces at varying frequencies; more frequent exposure was linked with more positive ratings. It's why consistent, repeated presence matters, though repetition of something people already dislike doesn't help.
Foot in the door. In one experiment, homeowners who first agreed to a small request were much more likely to later agree to a big one, such as a large sign in their yard. In product terms: small first commitments, like a free tool, before big ones.
Decoy effect. Adding an option that is clearly worse than one existing option shifted people toward that option. It's the logic behind some three-tier pricing pages. Used dishonestly, it becomes manipulation.
Choice overload. In a supermarket, a tasting table with 24 jams drew more shoppers than one with 6, but about 3% of shoppers at the large display bought, against about 30% at the small one. A 2010 meta-analysis of many later studies found the average effect close to zero, with large differences between settings. Fewer choices help sometimes. Test before you cut your menu.
Endowed progress. Car wash loyalty cards needing eight stamps were completed less often than cards needing ten stamps with two already filled in, even though both needed eight purchases. Onboarding checklists that start partly complete use the same idea; the progress should be real, not invented.
IKEA effect. Participants who assembled boxes or folded origami valued their creations more than identical ones made by others. It's one reason products that ask users to set things up themselves can feel more "theirs".
Zeigarnik effect. Unfinished tasks tend to stay on the mind. Later research has found the memory effect inconsistent, but the general idea, that open loops pull attention, is widely used in series and cliffhanger headlines.
Social proof. A broad body of research shows people follow others when uncertain. It's the case for showing real usage, real reviews and real numbers, and the reason faking them is so damaging when discovered.
How should you use them?
As ideas to test on your own audience, never as permission to mislead.
Write each idea as a hypothesis: "A checklist that shows one step already complete will raise completion." Run it as a test. Keep what works for your users. And keep it honest: fake countdown timers, invented scarcity and fake reviews can break consumer protection law as well as trust.
For headlines, several of these ideas show up as angles: curiosity (open loops), numbers (clear scope), and questions. The Headline Swapper generates those angles; whether they work for your audience is something only your own testing can show.
Questions
What is the IKEA effect?
The finding, from Norton, Mochon and Ariely (2012), that people value things more when they've put effort into making them, even simple things like assembling a storage box.
Did the jam study really show that more choice reduces sales?
In the original 2000 study, a display with 24 jams attracted more shoppers but led to fewer purchases than one with 6. Later meta-analyses found the choice overload effect varies a lot by setting and is sometimes absent.
Can I use these findings in my marketing?
Yes, as hypotheses. Test them on your own audience. And never use them to mislead, for example with fake scarcity or fake progress.
Sources
- Iyengar & Lepper (2000), When choice is demotivating, Journal of Personality and Social Psychology 79(6)
- Scheibehenne, Greifeneder & Todd (2010), Can there ever be too many options? A meta-analytic review, Journal of Consumer Research 37(3)
- Norton, Mochon & Ariely (2012), The IKEA effect, Journal of Consumer Psychology 22(3)
- Nunes & Drèze (2006), The endowed progress effect, Journal of Consumer Research 32(4)
- Freedman & Fraser (1966), Compliance without pressure, Journal of Personality and Social Psychology 4(2)
- Huber, Payne & Puto (1982), Adding asymmetrically dominated alternatives, Journal of Consumer Research 9(1)
- Zajonc (1968), Attitudinal effects of mere exposure, Journal of Personality and Social Psychology 9(2)