Delay discounting violations vary by adolescent sociodemographics: Excluding nonsystematic data may bias conclusions.

Delay discounting tasks are increasingly used across psychology to examine self-regulation and value-based decision making. These tasks assess how individuals devalue rewards as delays to receipt increase, with responses expected to follow a decreasing pattern. When participants report higher valuation at longer delays-a violation of this expected trend-such responses are often flagged as nonsystematic and, in many cases, excluded from analysis. Although intended to optimize data quality, such exclusions may systematically bias samples and distort downstream inferences. Using data from the Adolescent Brain Cognitive Development study (N = 11,307), we examined whether nonsystematic responding covaried with demographic, cognitive/behavioral, and environmental characteristics. Nearly half of participants exhibited at least one nonsystematic responding violation, with greater likelihood among youth from low-income households, low-resource neighborhoods, and racially minoritized backgrounds. Nonsystematic responding was also associated with lower abstract reasoning and higher positive urgency. Violations disproportionately occurred at the earliest presented task delays, suggesting a possible learning effect. These findings raise concerns that data exclusion criteria may bias behavioral samples and alter conclusions in translational research domains such as addiction science, behavioral pharmacology, and public health. (PsycInfo Database Record (c) 2026 APA, all rights reserved).