Nearly all forms of early memory are fragile, with examples of learning the alphabet or a new language, learning a new telephone number or a new computer password, or building motor memory for new motor skills. To build robust memory, the repetition of task-specific practice is critical.
At birth, the presence of the primitive survival reflexes hastens our learning for milk-feeding skills in support of our survival. When a breastfed infant is given a learning experience with an artificial nipple, the fragility of early motor memory is often on display for the infant's oral grasp of the nipple-areolar complex and/or effective suckling, i.e., the primitive survival reflexes are not equally weighted for all infant milk-feeding movements all the time, and a recency effect is often observed for the more recently learned milk-feeding method. Similarly, when an exclusively bottle-fed infant is given a learning experience with a different style of artificial nipple, immediate task-switching ability by the infant for the oral grasp of the novel artificial nipple, followed by a prompt and competent return to the original artificial nipple is not at all expected.
In the cognitive sciences, there is a well-known developmental progression of our cognitive flexibility for switching back and forth between tasks. Cognitive flexibility is most limited in the young, and the younger we are, the more limited our cognitive flexibility. Children display greater cognitive flexibility than infants, and adolescents display greater cognitive flexibility than children. Adults possess greatest cognitive flexibility, yet task-switching is often complex and demanding in adulthood as well.
Another tenet from the field of motor learning: The greater the difficulty of the task, the greater the need for practice that is specific to the task. A timely example of the critical need for task-specific practice will be in evidence in the U.S. tonight during Game 2 of the National Basketball Association (NBA) finals between the Cleveland Cavaliers and the Golden State Warriors. These elite athletes will never rehearse for competition with a novel basketball that differs in diameter, texture, weight, and/or bounce, followed by a sudden switch to a regulation-sized basketball for the fierce competition against their opponents. Furthermore, such a poor and unthinkable practice strategy is never recommended by the teams' coaches. As it is, these elite players must contend with environmental constraints in regard to changes in their visual field when they are not playing on their home court, and numerous formal studies have indeed shown a home court advantage (1).
When infants present with a recessed chin, tethered oral tissues, or cleft lip, for example, the task of learning the oral grasp at the breast and/or effective suckling may be more challenging for the infant. In the field of motor learning, such potential learning challenges are referred to as individual constraints. Task constraints may also be present, such as retracting nipple anatomy; and/or flat nipple anatomy that is not readily protractile; and/or inverted nipple anatomy; and/or and breast engorgement. These anatomical variations may also present temporary and transient challenges, moderate challenges, or more prolonged challenges for the infant who is learning the oral grasp and/or effective suckling at the breast.
The above-mentioned tenet is also applicable to newborns who are learning their first feeding skills, in that the greater the difficulty of the task, the greater the need for practice that is specific to the task, i.e., it is particularly important that artificial nipples are avoided in the presence of any possible learning constraints. This is not at all to say that artificial nipples should be offered to breastfed infants in the absence of any possible learning constraints, nor should it be said that exclusively bottle-fed infants should receive alternating learning experiences with different styles of artificial nipples, regardless of whether possible learning constraints are present. A reminder: cognitive flexibility is most limited in the young, and the younger we are, the greater the limitations in our cognitive flexibility.
The current widespread use of nipple shields in many childbearing settings in the U.S. often follows the infant's learning experience with an artificial nipple whether in non-Baby Friendly or Baby Friendly settings, even when an infant has initially learned the oral grasp at the breast, or when the infant is to become a breastfed infant but has not yet practiced feeding skills at the breast, having first learned bottle-feeding skills. Until the baby has the opportunities to learn or relearn feeding skills at the breast, a "home field advantage" is a standard recommendation, i.e., the rich sensory milieu of the mother's chest is recommended for the infant via skin-to-skin contact.
The frequent risks of task-switching are the well-known switch costs of decreased speed and accuracy for the task. Measurement parameters of motor performance as well as task-switching and switch costs include reaction time (RT), movement time (MT), response time (reaction time + movement time = response time), and the inhibition of return (IOR), the delay in responding to the previously cued (or orienting) stimulus. All of these parameters are measured in milliseconds (ms).
Pronounced and prolonged individual constraints may include complete cleft of the lip and palate until surgical repair takes place. In the absence of pronounced and prolonged learning constraints, many motor skills soon reach an elegant level of performance with effective practice that is specific to the task. For the infant's acquisition of milk-feeding skills, the baby's increasing expertise is evidenced by the rapid oral grasp, as well as the baby's ability to consistently and effectively transfer adequate volumes of milk over increasingly shorter periods of time. When the older baby is able to multi-task while nursing, such as reaching for his toes while feeding, or playing with a button on his mother's shirt while suckling, great heights in motor control have been reached. Such an "elite" level of performance for an infant is not achieved overnight but requires months of practice, even in the absence of any possible learning constraints.
1) Jamieson Jeremy P. The Home Field Advantage in Athletics: A Meta-Analysis. Journal of Applied Social Psychology 9 July 2010. https://doi.org/10.1111/j.1559-1816.2010.00641.x