The effects of stimulus symmetry on hierarchical processing in infancy.

The current study investigated the effects of stimulus symmetry on the processing of global and local stimulus properties by 6-month-old short- and long-looking infants through the use of event-related potentials (ERPs). Previous research has shown that individual differences in infant visual attention are related to hierarchical stimulus processing, such that short lookers show a global processing bias, while long lookers demonstrate a local processing bias (Guy, Reynolds, & Zhang, 2013). Additional research has shown that in comparison with asymmetry, symmetry is associated with more efficient stimulus processing and more accurate memory for stimulus configuration (Attneave, 1955; Perkins, 1932). In the current study, we utilized symmetric and asymmetric hierarchical stimuli and predicted that the presence of asymmetry would direct infant attention to the local features of stimuli, leading short lookers to regress to a local processing strategy. Results of the ERP analysis showed that infants familiarized with a symmetric stimulus showed evidence of global processing, while infants familiarized with an asymmetric stimulus did not demonstrate evidence of processing at the global or local level. These findings indicate that short- and long-looking infants, who might otherwise fail to process global stimulus properties due to limited visual scanning, may succeed at global processing when exposed to symmetric stimuli. Furthermore, stimulus symmetry may recruit selective attention toward global properties of visual stimuli, facilitating higher-level cognitive processing in infancy.

Neural correlates of individuation and categorization of other-species faces in infancy.

The goal of this study was to investigate 9-month-old infants' ability to individuate and categorize other-species faces at the subordinate level. We were also interested in examining the effects of initial exposure conditions on infant categorization and individuation processes. Infants were either familiarized with a single monkey face in an individuation procedure or familiarized with multiple exemplars of monkey faces from the same species in a categorization procedure. Event-related potentials were recorded while the infants were presented: familiar faces, novel faces from the familiar species, or novel faces from a novel species. The categorization group categorized monkey faces by species at the subordinate level, whereas the individuation group did not discriminate monkey faces at the individual or subordinate level. These findings indicate initial exposure to multiple exemplars facilitates infant processing of other-species faces, and infants are efficient at subordinate-level categorization at 9 months of age.