Concept
Dynamic Social Proof
social-proof marketing growth
A variant of Social Proof that highlights a growing trend ("more and more people are doing X") rather than a static majority ("most people do X"). Harry Dry notes this is specifically valuable for smaller brands and creators who aren't the established category leader, since a static-majority claim only works if you're already the biggest — a growth claim works at any absolute size.
Researchers Sparkman and Walton's 2017 study on restaurant meat-free ordering demonstrated the mechanism directly: a static-majority-style message ("30% of Americans reduce their meat consumption") actually backfired, since it implicitly signaled that most people don't reduce meat, functioning as negative social proof — only 17% chose a meat-free dish after reading it. A dynamic version of the identical statistic ("in the last five years, 30% of Americans have started to reduce their meat consumption") reframed the same number as a growing trend, and 34% chose the meat-free dish — a large relative improvement using the same underlying figure (see Sparkman Walton Dynamic Social Proof Study).
Harry Dry applies the same principle to his own newsletter growth messaging, favoring "400 new people are joining this newsletter every day" over "80,000 people have signed up over two years" — the growth figure, even though smaller in absolute terms, reads as more compelling proof of current momentum.
Two further real-world illustrations of the same static-norm backfire, one working and one not (Episode 256). A British university's campus campaign stating "the average student drinks six pints per night... stop binge drinking" backfired: students drinking less than six pints increased their own drinking to match the stated (undesirable) norm (see University Binge-Drinking Norm-Backfire Case). By contrast, Dutch bank ING's email telling under-saving customers they were saving less than most of their neighbors — framing saving more as the norm — increased engagement, while a Skin+Me SPF ad stating "91% of you do not apply enough SPF" repeats the university campaign's mistake, reinforcing under-application as the norm rather than correcting it (see ING and Skin+Me Norm-Framing Cases).
Named and broadened in a 2024 replication (Episode 280). Costello et al.'s seven-experiment paper, including field studies, dubs the mechanism the "uptrend effect" and confirms "more people are doing X now than before" outperforms "most people do X" specifically for uncommon health behaviors — the same pattern as the Sparkman/Walton study, now with a named effect and a broader evidence base.
Cialdini's own practical recommendation and supporting study (Episode 281). For a product/service without an existing popularity majority to cite, Cialdini recommends reporting a genuine upward trend across at least three data points (e.g. "15% two months ago, 20% last month, 30% this month") rather than a single static percentage, since a bare 30% figure also implies 70% haven't adopted it. His own water-conservation field study confirms the mechanism directly (see Cialdini Water-Conservation Trend-Framing Study).
Discussed in
- Episode 76 — 76- Harry Dry-s favorite marketing examples
- Episode 256 — 256-this-small-change-can-make-a-politician-electable (university binge-drinking backfire; ING and Skin+Me contrast)
- Episode 280 — 280-when-you-can-t-stop-seeing-the-thing-you-ve-just-discovered (Costello et al. "uptrend effect" replication)
- Episode 281 — 281-these-two-words-increased-sales-by-18-robert-cialdini (Cialdini's own trend-framing recommendation and water-conservation study)