Developing a self from the inside out: Investigating multisensory body awareness across human infancy and early toddlerhood

The processing and integration of sensory information originating from inside and outside the body provides a basis for our sense of self. Yet, how infants begin to navigate this interplay to perceive the body and its sentient experience in the world is unknown. Across four studies, this thesis aimed to examine the trajectory of interoceptive and exteroceptive body awareness across human infancy and early toddlerhood. Studies 1 and 2 tested theoretical proposals that parents’ own interoceptive abilities may be related to qualities of their caregiving interactions with their infant. According to the findings of these online studies, parents’ self-reported ability to regulate their own bodily states related to their reported engagement in specific caregiving behaviours. Studies 3 and 4 adopted a novel longitudinal approach, using a range of psychophysiological and behavioural methods, to elucidate the construction of bodily self-awareness across infancy and early toddlerhood. Specifically, in a sample of infants at 13- and 21-months-old, Study 3 traced the development of exteroceptive and interoceptive (cardiac) bodily self-awareness to test the theoretical account in adults that individuals differ in the extent to which their model of the self is biased towards interoceptive or exteroceptive sensations. The findings provide the first evidence that these individual differences exist in human infancy. In the same sample of participants, Study 4 built on the findings of the previous studies to examine whether caregiving interactions and parental self-reported interoception shape infants’ own developing interoceptive sensitivity. The findings extended those of Studies 1 and 2 to show that cardiac sensitivity at 21 months was predicted by the interaction between parental interoceptive self-regulation and interactional synchrony during a parent-infant interaction at 13 months. Taken together, the findings of this thesis have important theoretical implications for understanding the developmental pathways to self-awareness. Beyond this, the developmental approach taken here sheds light on the mechanisms supporting interoceptive body awareness that have otherwise been unobtainable from studies conducted with adults.