Dissociating top-down and bottom-up temporal attention in Down syndrome: A neurocostructive perspective

Recent studies suggest that both top-down and bottom-up temporal orienting (TO) of attention are established early and show stable trajectories in typical development. Yet, no evidence is available about atypical development of TO. In the present study, we first investigate the interplay between top-down and bottom-up temporal attention mechanisms in Down Syndrome (DS). Children and adolescents with DS (n = 33) and typically developing individuals matched to children with DS by either chronological (TD-CA; n = 33) or mental age (TD-MA; n = 31) performed a simple cued reaction time designed to assess top-down (endogenous TO) and bottom-up (foreperiod and sequential effect) temporal attention. Mean task accuracy was on average lower and more variable in the DS group than controls and it was predicted by both verbal and nonverbal ability. A subsample of high-performing children, showing comparable task speed and higher accuracy (>= 65%), was then extracted from each group to test the presence of top-down and bottom-up temporal attention while limiting possible floor effects and overly slow responding. While the control groups showed both top-down and bottom-up TO effects, only the latter were present in DS group. Consistent with a neuroconstructivist account, this study identifies an atypical domain-general cognitive mechanism, temporal orienting of attention, that may constrain the build-up of domain-specific skills in DS, and is for investigation in other atypically developing groups.