Humans are altricial, that is – they are born in an undeveloped state, incapable of caring for themselves. They require continuous caregiver attention in order for their survival needs to be met, and this need is especially pressing shortly after birth. Crying is the neonate’s mechanism for eliciting parental care, and over evolutionary time crying has likely become optimised to achieve this. This requires adaptation in both the infant and caregiver – on the side of the infant, to produce an effective cry and on the side of the caregiver, to be driven to respond to the cry by providing nurturing responses that ensure the infant’s survival. At the heart of this proposal lies a bipartite question: how do the relationships between cries and caregiving develop on an evolutionary timescale and how do they develop on an ontogenetic timescale? Thus, one strand of the proposed research aims to determine whether there is any empirical evidence for suggesting that the acoustics of neonatal cries confer a benefit to the infant, supporting an evolutionary argument for their development as a survival mechanism. A second strand is the empirical investigation of the developmental timecourse of the neural substrates that underlie the production of these, presumably optimised, neonatal cries.
Newborn infants have been shown to produce spontaneous cries that are natively-accented - they have a pitch-contour consistent with that of the language prevalent in the environment in which they gestated. It may be supposed that an ability present at birth is highly relevant to the infant’s survival, but the role of accented crying in neonates is unknown. I hypothesise that in addition to providing a functional basis for future articulatory skills, crying with a native accent subserves a direct and immediate survival function. Crying can elicit the attention of caregivers, but crying is both salient and aversive. An infant that is salient but excessively aversive may not elicit care but potentially detrimental, indeed abusive, responses. I suggest that cry melody helps to render cries maximally salient while mitigating aversiveness. In order to assess this, I will use a large-scale crowd-sourced behavioural investigation to examine the role of cry melody in modulating subjective aversiveness and salience, followed by an investigation of the impact of cry melody on autonomic responses, using eye-tracking. This will be followed up by a large-scale neuroimaging investigation examining how cry melody affects the engagement of the adult cry-processing network, and in particular the subnetworks associated with executing care-giving activity.
I further hypothesise that there is well-developed in utero mechanism that allows the fetus to acquire the articulatory motor patterns necessary for producing accented cries. This mechanism involves an automatic mapping of speech experienced in utero onto motor substrates, thereby tuning the fetal motor system to the properties of the environmental language. In order to test this, I will use in utero imaging. In a first instance I propose to use publicly available fetal imaging datasets (offered by the Developmental Human Connectome Project) to provide insights into the functional and structural development of the relevant neural pathways. A second strand will use in utero functional MRI in a large sample of third trimester fetuses to probe whether fetal brain responses to auditory stimulation, in particular by speech are coupled to motor responses, thus providing the first documented evidence of the existence of the requisite cerebral mechanisms in utero. A final experiment will examine whether there is a fetal articulatory-motor response to hearing speech in utero, to evaluate whether there is a mechanism that induces fetal mirroring of speech sounds.
By elucidating the role of natively-accented crying this project re-evaluates neonatal crying as a communicative act, illustrates the importance and sophistication of fetal learning and expands our understanding of the development of the neurophysiology of speech production. The project is integrated into major inter-disciplinary strategic initiatives at UZH (e.g. the Linguistic research Infrastructure and the development of fetal MRI at the University Children’s Hospital), which allows this to be investigated in an integrated, interdisciplinary manner, laying fertile ground for future investigations of infant language development and parent-infant interaction, from developmental and evolutionary perspectives.