Dissociable contributions of goal-relevant evidence and goal-irrelevant familiarity to n-back performance in youth

Abstract

Recent studies using the diffusion decision model (DDM) find that performance across many cognitive control tasks, including the n-back, can be largely attributed to a task-general efficiency of evidence accumulation (EEA) factor that reflects individuals’ ability to selectively gather evidence relevant to task goals. However, estimates of EEA across different n-back conditions in the Adolescent Brain Cognitive Development (ABCD) Study, a large, diverse sample of youth, appear to contradict these findings. EEA estimates from “lure” trials – which present stimuli that are familiar (i.e., presented previously) but do not meet formal criteria for being a target – show inconsistent relations with EEA estimates from other trials and display atypical v-shaped bivariate distributions, suggesting many individuals are responding based largely on stimulus familiarity rather than goal-relevant stimulus features. We present a new formal model of evidence integration in the n-back task that distinguishes individuals’ EEA for goal-relevant evidence from their use of goal-irrelevant familiarity evidence. We then investigate developmental, cognitive, and clinical correlates of these novel parameters. Parameters for goal-relevant EEA and goal-irrelevant familiarity-based processing showed similarly strong correlations across levels of n-back load, suggesting they are task-general dimensions that influence individuals’ performance regardless of working memory demands. Only EEA showed large, robust developmental differences in the ABCD sample and an independent age-diverse sample. EEA also exhibited higher test-retest reliability and correlations with cognitive and clinical dimensions. These findings establish a principled modeling framework for characterizing cognitive mechanisms underlying n-back performance in youth and have several broader implications for research on neurocognitive development.