Object representations and physical reasoning in the infant brain

• Behavioral evidence indicates infants understand that understand basic properties of physical objects from birth but gradually learn about physical properties such as support through development (Baillargeon 1998). • fMRI research has shown that infants have object responses across cortex (Deen et al. 2017; Livingstone et al. 2017) but the degree to which different regions of the infant brain respond to similar or different properties has never been probed. • In adults, the lateral-occipital complex (LOC) responds to shape, the ventral temporal cortex (VTC) responds to higher-level categorical object features, and parietal cortex responds object interactions (Yildirim et al. 2019). • A lateral-occipital, ventral-temporal, and two parietal regions have been implicated in intuitive physical reasoning in adults (Fischer et al. 2016). • Infant lateral-occipital cortex responds to shape but not texture or color (Emberson et al. 2017). Research Question: Do regions that support object representations and physical reasoning in adults have similar functional profiles in infancy? Hypotheses: • Parietal cortex in infants is engaged in physical inference such as object motion, interaction, solidity, and support. • Object cortex in infant VTC represents object-specific properties invariant to orientation. • LOC in infants represent general shape features independent of object identity (i.e., a response that is not invariant to orientation). Predictions: • In infant LOC, object responses will be similar to face and body responses and different than scene responses. • In infant VTC, object responses will be similar to scene responses and different than face and body responses. • In the parietal regions, one prediction is that the response will be adult-like (objects>bodies>scenes>faces). An alternative possibility that is supported by behavioral studies(Saxe, Tzelnic, and Carey 2006) is that for infants, object responses will be similar to body responses and different than face and scene responses (objects~bodies>scenes~faces). Finally, it is possible that one parietal region (lateral or middle) will have the adult like pattern and one will not. Alternatively, it is possible that the infant brain will not distinguish the relatively fine-grained differences between these stimuli that we hypothesize and/or that these stimuli do not adequately represent the type of physical reasoning infants are capable of.