B
Evidence Grade B
Graded
accuracy verified by the review judge
Safe to Cite
Current
7.92%
7.92% -- theft rate for Petrified Forest visitors (Cialdini experiment) (2026)
In Cialdini's Petrified Forest experiment, the theft rate was 7.92% when visitors were shown a sign indicating past theft.
- Result occurred when using negative social proof messaging compared to a 2.92% control rate with no sign
Attribution:
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Lighthouse Research Team
Last verified:
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Source verified
Evidence graded
Value
7.92%
Unit
Percentage
Data Vintage
2026
Entity
Evidence Quality
B
Strong, reliable evidence
Sourced from a well-regarded research firm or industry leader with transparent methodology and a reasonably large sample.
Single source - not yet corroborated
Score breakdown
Extraction
50
Source Trust
60
Citation Chain
20
Independence
30
Methodology
45
Freshness
95
Source
Robert Cialdini
Primary
Tier C
https://kirro.io/social-proof-examples ↗
Source Article
15 Social Proof Examples That Actually Convert (2026)
Social proof is people copying other people. That’s it. You check restaurant reviews before booking. You read testimonials before buying software. You pick the busier coffee shop over the empty one. All social proof. And it works: products with just five reviews sell 270% better than products with z…
Original Research
Robert Cialdini
· Original study ↗
Methodology
Cialdini field experiment at Arizona's Petrified Forest, cited by kirro.io
Methodology documented
Segmentation
Industrymarketing
Cite this stat
Plain Text
Petrified Forest visitors (Cialdini experiment): 7.92% theft rate. Source: Robert Cialdini (2026). Via Lighthouse Intelligence -- https://lighthousedata.io/data/petrified-forest-theft-tripled
HTML Embed
<blockquote cite="https://lighthousedata.io/data/petrified-forest-theft-tripled" style="border-left:3px solid #2563eb;padding:12px 16px;margin:16px 0;font-family:system-ui,sans-serif;background:#f0f4ff;"><strong>7.92%</strong> -- theft rate for Petrified Forest visitors (Cialdini experiment)<br><small>Source: Robert Cialdini (2026) · <a href="https://lighthousedata.io/data/petrified-forest-theft-tripled" target="_blank" rel="noopener">Lighthouse Intelligence</a></small></blockquote>
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