Consumer Credit with Over-Optimistic Borrowers

Do cognitive biases call for regulation to limit the use of credit? We incorporate over-optimistic and rational borrowers into an incomplete markets model with consumer bankruptcy. Over-optimists face worse income risk but incorrectly believe they are rational. Thus, both types behave identically. Lenders price loans forming beliefs—type scores—about borrower types. This gives rise to a tractable theory of type scoring. As lenders cannot screen types, borrowers are partially pooled. Over-optimists face cross subsidized interest rates but make financial mistakes: borrowing too much and defaulting too late. The induced welfare losses outweigh gains from cross subsidization. We calibrate the model to the U.S. and quantitatively evaluate policies to address these frictions: financial literacy education, reducing default cost, increasing borrowing costs, and debt limits. While some policies lower debt and filings, only financial literacy education eliminates over borrowing and improves welfare. Score-dependent borrowing limits can reduce financial mistakes but lower welfare.