Thinking—Fast, Slow, and Artificial: How AI is Reshaping Human Reasoning and the Rise of Cognitive Surrender

People increasingly consult generative artificial intelligence (AI) while reasoning. As AIbecomes embedded in daily thought, what becomes of human judgment? We introduceTri-System Theory, extending dual-process accounts of reasoning by positing System 3: artificialcognition that operates outside the brain. System 3 can supplement or supplant internalprocesses, introducing novel cognitive pathways. A key prediction of the theory is“cognitive surrender”—adopting AI outputs with minimal scrutiny, overriding intuition(System 1) and deliberation (System 2). Across three preregistered experiments using an adaptedCognitive Reflection Test (N = 1,372; 9,593 trials), we randomized AI accuracy via hidden seedprompts. Participants chose to consult an AI assistant on a majority of trials (>50%). Relative tobaseline (no System 3 access), accuracy significantly rose when AI was accurate and fell when iterred (+25/-15 percentage points; Study 1), the behavioral signature of cognitive surrender(AI-Accurate vs. AI-Faulty contrast; Cohen’s h = 0.81). Engaging System 3 also increasedconfidence, even following errors. Time pressure (Study 2) and per-item incentives and feedback(Study 3) shifted baseline performance but did not eliminate this pattern: when accurate, AIbuffered time-pressure costs and amplified incentive gains; when faulty, it consistently reducedaccuracy regardless of situational moderators. Across studies, participants with higher trust in AIand lower need for cognition and fluid intelligence showed greater surrender to System 3.Tri-System Theory thus characterizes a triadic cognitive ecology, revealing how System 3reframes human reasoning and may reshape autonomy and accountability in the age of AI.