*2.1. Participants*

Seven infants with Down syndrome (mean age = 6 months; age range from 5 months and 3 days to 7 months and 20 days; 3 males) and 24 typically developing infants (mean age = 5.25 months; age range from 5 months and 2 days to 6 months and 28 days; 16 males) took part in this study. DS infants were recruited from the Center for Child Development Diferenças in Lisbon, Portugal. They were born full-term and had normal hearing to mild hearing loss and normal or corrected-to-normal vision (according to clinical screening). TD infants were all born full-term, with no reported medical/developmental concerns. Additionally, questionnaires on language and overall development (see details in Materials and Procedure) served as a screening tool to confirm TD infants' development. All infants were raised in monolingual European Portuguese homes. The study was approved by the Ethical Committee for Research of the School of Arts and Humanities of the University of Lisbon.
