Developing system 1: knowledge automatization drives sound intuiting

Recent dual-process research shows that adults can generate correct responses intuitively, whereas younger reasoners rarely do so. Yet the nature of their lower intuitive accuracy remains unclear. Does it reflect a general deficit in intuitive ("System 1") reasoning, or simply more limited task practice? We addressed this by manipulating task familiarity in two studies with 7^th-grade adolescents (approximately 12 years old). We contrasted performance on numerical reasoning tasks involving well-practiced logico-mathematical principles for these students (Study 1: arithmetic word problems; Study 2: decimal comparison) with a task involving a less-practiced principle (the bat-and-ball problem). Using a two-response paradigm, participants first provided an answer under time pressure and cognitive load, followed by a final, unconstrained answer to distinguish intuitive from deliberate reasoning. Across both studies, correct responses on well-practiced tasks were predominantly intuitive, whereas both intuitive and deliberative accuracies were low on the less-practiced task. This supports the view that correct intuitive reasoning depends on prior knowledge automatization and provides evidence against a generic "System 1" developmental deficit.