A5
Framing & ReferenceEndowment Effect
Ownership should not affect valuation
5
Models Tested
3
Confirmatory
0.787
Mean Effect
1.772
Max Effect
Theoretical Context
Theoretical Anchor
Thaler (1980)
Normative Violation
Ownership should not affect valuation
Cross-Model Comparison
Effect sizes for Endowment Effect across all tested models
OpenAI
GPT-5.4 Thinking
The Deliberative Calibrator
h = +1.772Confirmatory
OpenAI
GPT-5.2
The Steady Traditionalist
h = +0.877Confirmatory
OpenAI
GPT-5.3 Instant
The Directive Optimist
h = +0.876Confirmatory
Google
Gemini 2.0 Flash
The Consistent Optimist
h = +0.288
Anthropic
Claude Sonnet 4.6
The Cautious Contrarian
h = +0.119
Statistical Details
Full results with confidence intervals and sample sizes
| Model | n (A) | n (B) | Cohen's h | 95% CI | Status |
|---|---|---|---|---|---|
| GPT-5.4 Thinking | 50 | 50 | +1.7722 | — | Confirmatory |
| GPT-5.2 | 50 | 50 | +0.8770 | — | Confirmatory |
| GPT-5.3 Instant | 50 | 50 | +0.8763 | — | Confirmatory |
| Gemini 2.0 Flash | 50 | 50 | +0.2882 | — | Exploratory |
| Claude Sonnet 4.6 | 50 | 50 | +0.1189 | — | Exploratory |