Conditional learning abilities in Down syndrome and Williams syndrome

Abstract

We investigated whether individuals with Down (DS) or Williams (WS) syndrome are capable of conditional learning, a hippocampus-dependent process enabling flexible reasoning, using three touch-screen tasks: a visual learning task to assess unconditional learning (A > B and C > D), a 3-item conditional learning task (A > B, B > C), and a 5-item conditional learning task (A > B, B > C, C > D, D > E) to further assess transitive inference abilities. We compared the performance of individuals with DS or WS to typically developing 3–12-year-old children and 20–30-year-old adults. Most participants exhibited unconditional learning, but only 12% of individuals with DS, 15% of individuals with WS, and 42% of children exhibited conditional learning, as compared to 95% of young adults; only adults demonstrated transitive inference. Our findings indicate that conditional learning and transitive inference, which depend on brain structures impacted in these disorders, including the hippocampus and the prefrontal cortex, are beyond reach for most individuals with DS and WS.