biostudies-literatureUnknown4(1)Wu QHonda Research Institute USAThe origins of human prosociality, in particular between strangers, are multifaceted. While laboratory studies support a cost-benefit account of helping, real-life scenarios involve additional socio-emotional motives grounded in subjective intuitions. How the cost-benefit model generalizes to everyday helping behavior remains unclear. In this study, we comprehensively assessed how motivations jointly shape helping across 100 naturalistic helping scenarios: an online sample (N<sub>1</sub> = 215) rated willingness to help after reading brief vignettes, and a subset (N<sub>2</sub> = 140) rated the strengths of candidate motivations elicited by each scenario. Two key factors-benefit to both helper and helpee, and cost to the helper-were identified through a factor analysis of the motivation raCommunications psychology2https://www.ebi.ac.uk/biostudies/studies/S-EPMC12770495biostudies-literatureProsocial decisions in naturalistic helping scenarios are predicted by cost-benefit tradeoffs and individual disposition.PMC12770495Dunning DSong MWu QTian DAyoub JMoradi-Pari EfalseProsocial decisions in naturalistic helping scenarios are predicted by cost-benefit tradeoffs and individual disposition.The origins of human prosociality, in particular between strangers, are multifaceted. While laboratory studies support a cost-benefit account of helping, real-life scenarios involve additional socio-emotional motives grounded in subjective intuitions. How the cost-benefit model generalizes to everyday helping behavior remains unclear. In this study, we comprehensively assessed how motivations jointly shape helping across 100 naturalistic helping scenarios: an online sample (N<sub>1</sub> = 215) rated willingness to help after reading brief vignettes, and a subset (N<sub>2</sub> = 140) rated the strengths of candidate motivations elicited by each scenario. Two key factors-benefit to both helper and helpee, and cost to the helper-were identified through a factor analysis of the motivation ra2025-01-01T00:00:00Z2025 Dec2026-06-11T04:51:09.493Z2026-06-11T03:08:06.373ZS-EPMC127704954142233910.1038/s44271-025-00371-x