Historically, newborns, and especially premature newborns, were thought to "feel nothing." However, over the past decades, a growing body of evidence has shown that newborns are aware of their environment, but the extent and the onset of some sensory capacities remain largely unknown. The goal of this review is to update our current knowledge concerning newborns' perceptual world and how ready they are to cope with an entirely different sensory environment following birth. We aim to establish not only how and when each sensory ability arises during the pre-/postbirth period but also discuss how senses are studied. We conclude that although many studies converge to show that newborns are clearly sentient beings, much is still unknown. Further, we identify a series of internal and external factors that could explain discrepancies between studies, and we propose perspectives for future studies. Finally, through examples from animal studies, we illustrate the importance of this detailed knowledge to pursue the enhancement of newborns' daily living conditions. Indeed, this is a prerequisite for assessing the effects of the physical environment and routine procedures on newborns' welfare.
Despite a growing body of research on perinatal sensory abilities, data on the extent of tactile sensitivity and more particularly passive touch (i.e. sensitivity to a stimulation imposed on the skin) are relatively limited, and the development and processing of tactile function are still thus little known. This question is particularly of high importance for infants with atypical early development such as those born prematurely who are exposed to many sensory (including tactile) stimulations (being in a hospital setting) during a critical period of brain development and those born at early term whose birth occurs at the precise time of cortical reorganization, in particular in the sensory areas. Some parents and health-care providers have for instance reported that children born prematurely exhibit atypical (e.g. higher) sensitivity to "benign" tactile stimuli. In the present study, we hypothesized that preterm and earlyterm infants may show altered tactile sensitivity. We compared the behavioral responses around term-equivalent age of infants born either pre-term, early-term or at term to the application of a light (0.008 grams) mechanical stimulus. We found that almost all preterm infants perceive this tactile stimulus, contrarily to the two other groups of infants. This extreme tactile sensitivity may be due to experiential, maturational or more likely both processes. We also compared the tactile sensitivity of these infants to that of adults. We found that adults were irresponsive to the light mechanical stimulus. This finding opens not only new insights in understanding development of tactile processing, but also new lines of thought about the particular sensory world of premature and early-term infants and hence about the potential impact of early care practices.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.