Comparing feedback learning and arousal responses in Down, Fragile X, and Williams syndromes.

Mechanisms underlying feedback learning in intellectual disability (ID) remain poorly understood. Down syndrome (DS), Fragile X syndrome (FXS), and Williams syndrome (WS) are genetic syndromes associated with ID, with distinct attention and arousal regulation profiles. Pupil dilation is a well-established index of feedback processing in typical development; little is known about these processes in non-social learning in these syndromes. Participants with DS (n = 13), FXS (n = 13), WS (n = 27), and typically developing (TD) individuals (n = 56) aged 6-60 years completed a reward contingency reversal task while eye-tracking recorded pupil dilation and gaze allocation. Data were analyzed using Bayesian mixed-effects models. All groups effectively learned from feedback, staying with rewarded options and switching after losses. WS participants performed similarly to TD participants. DS and FXS individuals showed more variable behavioral performance, indicating potential individual differences in feedback processing that warrant further investigation. Physiologically, TD individuals showed greater pupil dilation following losses than wins, whereas WS individuals showed no difference, suggesting attenuated physiological sensitivity to feedback valence. All groups tended to fixate on the previously rewarded options. This research highlights the value of combining behavioral and physiological approaches in ID research.