Global and Local Processing of Letters and Faces in Children and Adolescents with Typical and Atypical Development

Background/Objectives: this paper investigates the local vs. global visual processing preference in typically developing (TD) children, youth with Down syndrome (DS), and youth with Williams syndrome (WS). In particular, the global precedence effect (GPE) and the global interference effect (GI) have recently been described as two distinct and at least partially independent effects. Methods: in this study, 50 participants (TD = 25, DS = 13, WS = 12) completed two experiments requiring the identification of either the global or local level of hierarchical stimuli, which consisted of letters and schematic faces. For each stimulus type, two separate blocks were conducted, one with the task to focus on the local elements and the other with the task to focus on the global shape. Results: our results indicate that TD children demonstrate a global precedence effect for letters but not for schematic faces, suggesting a developmental modulation of configural processing. In contrast, both DS and WS groups showed a global processing bias for schematic faces and a significant global interference effect in both conditions, likely reflecting deficits in inhibitory control. Conclusions: these findings challenge the notion that DS and WS individuals can be classified strictly as global or local processors, respectively, emphasizing the influence of stimulus type and cognitive demands. Implications for neurodevelopmental research and clinical interventions are discussed.