Garbage in, garbage out: stringent quality control of behavioral data boosts signal in brain-behavior associations.

Low reproducibility in brain-behavior association studies has prompted calls for larger samples, but rigorous quality control (QC) of behavioral measures may also strengthen the robustness of observed associations. This study examined how varying levels of behavioral QC affect brain-behavior associations using delay discounting, a widely studied measure of immediate reward orientation. Data were drawn from the Adolescent Brain and Cognitive Development Study (n = 10,936), and delay discounting data were subjected to eight increasingly stringent QC levels. Associations between delay discounting and brain structural morphometry were evaluated in 15 bilateral a priori regions of interest (ROIs), and changes in effect size, significant associations, and multivariate behavioral prediction were quantified across QC levels. Greater QC stringency substantially amplified association strength, with effect sizes increasing by an average of 188.52% across ROIs, the number of statistically significant associations more than doubling, and multivariate prediction improving by 267%. Although higher QC levels reduced sample size by up to 65%, strengthening of associations plateaued at intermediate levels, suggesting asymptotic improvements in resolution. Overall, stringent behavioral QC substantially increased the magnitude of brain-behavior associations, suggesting this is a critical methodological consideration for improving reproducibility in cognitive neuroscience.