The Bayesian Origin of the Probability Weighting Function in Human Representation of Probabilities

Fuente: arXiv
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Autores principales: Tong, Xin, Hoang, Thi Thu Uyen, Wei, Xue-Xin, Hahn, Michael
Formato: Preprint
Publicado: 2025
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author Tong, Xin
Hoang, Thi Thu Uyen
Wei, Xue-Xin
Hahn, Michael
author_facet Tong, Xin
Hoang, Thi Thu Uyen
Wei, Xue-Xin
Hahn, Michael
contents Humans systematically misrepresent probability in a stereotyped inverse-S pattern. It has been documented for decades, but its origin remains unexplained. We propose a Bayesian encoding-decoding account in which probabilities are represented by noisy internal signals and decoded by Bayes-risk minimization. For bounded probability stimuli, we show that distortion decomposes into boundary regression, likelihood repulsion, and prior attraction, yielding a key prediction: the classic inverse-S-shaped weighting pattern implies a U-shaped allocation of encoding precision with greater sensitivity near 0 and 1. Across judgment of relative frequency, lottery pricing, and risky choice, this U-shape is recovered from data without imposing any functional form on the encoding, and our framework outperforms deterministic weighting functions, bounded log-odds models, uniform-encoding Bayesian accounts, and matched efficient-coding models on held-out data. In a new dot probability estimation experiment with bimodal stimulus statistics, the recovered prior tracks the new distribution while the recovered encoding remains U-shaped. Together, these results identify the inverse-S-shaped probability weighting function as the joint product of a stable U-shaped encoding and a flexible prior, integrated by optimal Bayesian decoding.
format Preprint
id arxiv_https___arxiv_org_abs_2510_04698
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Bayesian Origin of the Probability Weighting Function in Human Representation of Probabilities
Tong, Xin
Hoang, Thi Thu Uyen
Wei, Xue-Xin
Hahn, Michael
Neurons and Cognition
Artificial Intelligence
Theoretical Economics
Humans systematically misrepresent probability in a stereotyped inverse-S pattern. It has been documented for decades, but its origin remains unexplained. We propose a Bayesian encoding-decoding account in which probabilities are represented by noisy internal signals and decoded by Bayes-risk minimization. For bounded probability stimuli, we show that distortion decomposes into boundary regression, likelihood repulsion, and prior attraction, yielding a key prediction: the classic inverse-S-shaped weighting pattern implies a U-shaped allocation of encoding precision with greater sensitivity near 0 and 1. Across judgment of relative frequency, lottery pricing, and risky choice, this U-shape is recovered from data without imposing any functional form on the encoding, and our framework outperforms deterministic weighting functions, bounded log-odds models, uniform-encoding Bayesian accounts, and matched efficient-coding models on held-out data. In a new dot probability estimation experiment with bimodal stimulus statistics, the recovered prior tracks the new distribution while the recovered encoding remains U-shaped. Together, these results identify the inverse-S-shaped probability weighting function as the joint product of a stable U-shaped encoding and a flexible prior, integrated by optimal Bayesian decoding.
title The Bayesian Origin of the Probability Weighting Function in Human Representation of Probabilities
topic Neurons and Cognition
Artificial Intelligence
Theoretical Economics
url https://arxiv.org/abs/2510.04698