it may be that deprivation of grasping experience within the first 3 months of life leads to a deficit in grasping skill in later months.
The absence of or deficiency in the respiratory occlusion response may be related to the occurrence of the still unexplained, so-called "crib death" that takes the lives of a large number of infants at around 2 and 3 months of age. Many infants who succumb as "crib death" cases are known to have had a mild cold, usually described as "sniffles," just prior to their unfortunate death. Still others have been diagnosed on autopsy as having pneumonitis, presumably not so serious as to cause death. It is an empirical problem for developmental psychologists and psychobiologists to determine whether respiratory occlusion, and the failure to make appropriate adjustive responses to such occlusion, are pertinent factors in such deaths. Throat-clearing responses in the older child and adult are so prevalent and facile that, as with so many mature and fairly universal behaviors, we do not concern ourselves much with their ontogeny. It is possible, however, that just as learning (and failure to learn) are important antecedents of life-saving responses (and their absence) in other spheres of human activity, so also is the learning of maneuvers to prevent respiratory occlusion necessary for the survival of the infant.
It is not inconceivable that a modicum of early practice is required for the infant to achieve a suitable level of "respiratory retrieval" when faced with the threat of occlusion. The infants who achieve the required minimum of practice are perhaps those whose experience at retrieval has been most frequent and most vigorous. These would be the infants who at birth and shortly thereafter have vigorous responses to the threat of a respiratory occluding stimulus. That is to say, most practice in this situation is probably self-administered, as the baby lies in his crib, especially in the prone position, and as the infant moves around among blankets, hands, and other objects that are so readily brought to the mouth by the infant's own arms. In this connection, one wonders whether the lethargy of response displayed by the "failure-to-thrive infant" may not have had its earliest representation in a deficiency of this and similar neonatal response patterns, or in the failure of opportunity to practice early congenital patterns of behavior.
Anastasi, A. Heredity, environment, and the question "How? Psychological Review, 1958, 65, 197-208.