The Human Face Becomes Mapped as a Sensorimotor Reaching Space During the First Year

Trajectories of brain and behaviour development in the womb, at birth and through infancy

Birth is often seen as the starting point for studying effects of the environment on human development, with much research focused on the capacities of young infants. However, recent imaging advances have revealed that the complex behaviours of the fetus and the uterine environment exert influence. Birth is now viewed as a punctuate event along a developmental pathway of increasing autonomy of the child from their mother. Here we highlight (1) increasing physiological autonomy and perceptual sensitivity in the fetus, (2) physiological and neurochemical processes associated with birth that influence future behaviour, (3) the recalibration of motor and sensory systems in the newborn to adapt to the world outside the womb and (4) the effect of the prenatal environment on later infant behaviours and brain function. Taken together, these lines of evidence move us beyond nature-nurture issues to a developmental human lifespan view beginning within the womb.

Self-recognition: From touching the body to knowing the self

Recognizing oneself in a mirror is a classic test of self-concept. A new study has revealed the perceptual-motor foundations of conceptual self-knowledge: infants' success in the mirror test was accelerated after touching a tactile stimulus while viewing themselves in a mirror.

Tactile localization promotes infant self-recognition in the mirror-mark test

Mirror self-recognition has been hailed by many as a milestone in the acquisition of self-awareness with respect to phylogenesis and human ontogenesis.1,2,3,4,5,6 Yet there has been considerable controversy over the extent to which species other than humans and their closest primate relatives are capable of mirror self-recognition, and to the mechanisms that give rise to this ability.1,7 One influential view is that mirror self-recognition in humans and their closest primate relatives is a cognitive advance that is a product of primate evolution, stemming from more recently evolved neural structures and networks that develop through experience-independent mechanisms during ontogenesis.1 In contrast, we show that the development of mirror self-recognition in human infants is a perception-action achievement, building on infants' ability to localize and reach to targets on the body. Infants who were given experience reaching to tactile targets on their bodies in the months prior to recognizing themselves in a mirror achieved mirror self-recognition earlier than infants in either a yoked age-matched control group or a longitudinal control group without such experience. Our results demonstrate that self-touch functions as an intermodal gateway through which infants learn how to localize and reach to stimuli on their bodies, including those that can only be seen in a mirror. These findings identify an overlooked role for the routine activity of self-touch in establishing a representation of the body and suggest that the development of human self-awareness is rooted in self-directed action.

Tactile training facilitates infants' ability to reach to targets on the body

This longitudinal study investigated the effect of experience with tactile stimulation on infants' ability to reach to targets on the body, an important adaptive skill. Infants were provided weekly tactile stimulation on eight body locations from 4 to 8 months of age (N = 11), comparing their ability to reach to the body to infants in a control group who did not receive stimulation (N = 10). Infants who received stimulation were more likely to successfully reach targets on the body than controls by 7 months of age. These findings indicate that tactile stimulation facilitates the development of reaching to the body by allowing infants to explore the sensorimotor correlations emerging from the stimulation.