Less systematic decision-making during delay discounting, but not discounting rate, is robustly linked to psychopathology.

Delay discounting, the preference for smaller rewards available sooner over larger rewards available later, exhibits robust individual differences and is thought to contribute to risky behaviors, problematic substance use, and a variety of psychiatric disorders. An individual's behavior on delay discounting tasks is often measured using a hyperbolic discounting model, but this model does not account for inconsistent or nonsystematic choices, which can lead to high rates of exclusions. The practice of excluding participants whose behavior is not perfectly systematic can bias results and is inconsistent with a wealth of cognitive science research demonstrating that nonsystematic responses are a characteristic feature of human decision-making. Here, we extended the hyperbolic discounting model to include a parameter that accounts for systematic decision-making and explored how individual differences in systematicity and discounting rate differentially relate to psychopathology and cognition. In a data set of 8,884 adolescents, we found robust relationships between systematicity, but not discounting rate, and parent-, teacher-, and self-report measures of attention problems, internalizing psychopathology, and externalizing psychopathology. Systematicity was also related to cognitive ability, executive functioning, and other parametric measures of noisy decision-making. These findings were then replicated in an independent sample of 115 young adults. Overall, these results suggest the need for further examination of findings in the existing delay discounting literature and emphasize the importance of capturing decision-making mechanisms beyond discounting rate. (PsycInfo Database Record (c) 2026 APA, all rights reserved).