On Skin-to-Skin Contact, Associative Learning, and Reward-Based Learning

Across the lifespan, the learning of all feeding and drinking skills reflects procedural learning, reinforcement learning, reward-based learning, and associative learning. During associative learning, we learn to predict relationships, such as between two or more stimuli, a stimulus and a response, and between a response and its consequence.

For young newborns, learning milk-feeding skills is supported and hastened by the primitive survival reflexes, pre-adapted movements that are further adapted during sensory-perceptual-motor learning. The crawl reflex enables us to “drive” to nature’s first restaurant, and the rooting reflex further orients us to the dining location. As the infant determines the action (action planning) of moving still closer toward the nipple-areolar complex, a reflexive lunge is displayed by the infant toward the breast, in tandem with a reflexive wide open gape, with the tongue extended over the lower alveolar ridge. When the baby learns how to achieve and sustain the oral grasp, the suck reflex is soon stimulated. In mutuality and reciprocity between both members of the dyad, milk is released via the initial Milk Ejection Reflex (MER) as well as subsequent MERs in the same meal, much like service at a fine dining establishment, as one course at a time is served. Should the flow of milk temporarily overwhelm the young novice, the cough reflex helps us to reorganize our swallowing movements. With the repetition of practice, the baby’s suck reflex becomes increasingly more coordinated with the swallow reflex, in support of increasing motor control for the infant’s effective transfer of milk.

However, the remarkable presence of the primitive survival reflexes does not guarantee the oral grasp and effective sucking for all infant milk-feeding methods all the time. Following a learning experience with an artificial nipple and the subsequent return to the breast, skill decay (decreased speed and accuracy) is often observed for the baby’s oral grasp/latch at the breast, and/or effective sucking for adequate milk transfer, reflecting the cognitive demands of task-switching. These cognitive demands are particularly pronounced during early learning when memories are in their most fragile state, and furthermore, the younger we are, the greater the cognitive demands of task-switching.

When clinicians are called upon to assist the infant in a transfer of learning from artificial nipple to the breast, finger-feeding is often a highly effective technique in helping the infant learn to associate the smell, touch, and taste of the mother or other caregiver’s skin with sucking and receiving milk. In the language of the cognitive sciences, this pairing of associates is critical for learning and re-learning. However, the very first clinical recommendation is often skin-to-skin contact ad lib, also to familiarize the infant with that rich sensory milieu, including the visual field of that feeding location.

Susan Ludington, RN CNM PhD FAAN is the Executive Director of the United States Institute for Kangaroo Care (USIKC). Ludington has been studying skin-to-skin contact via Kangaroo Care since 1988, and offers this extensive annotated bibliography and reference list on the USIKC website. http://www.kangaroocareusa.org/uploads/KCBIB2018.pdf

Associative learning is heavily studied in the cognitive sciences, as is reward-based learning, reinforcement learning, and procedural learning. Some recent studies:

Title: Pavlovian reward learning elicits attentional capture by reward-associated stimuli.

Authors: Mine C, Saiki J.

In: Attention, Perception & Psychophysics 2018 Jul;80(5):1083-1095. doi: 10.3758/s13414-018-1502-2.


Title: I like it by mere association: Conditioning preferences in infants.

Authors: Jenny L Richmond, Jenna Zhao, Gabrielle Weidenmann.

In: Journal of Experimental Child Psychology 2017 September;161:19-31. doi: 10.1016/j.jecp.2017.03.015.


A new meta-analysis on associative word learning and task-switching in infancy:

Title: Associative word learning in infancy: A meta-analysis of the switch task.

Authors: Tsui ASM, Byers-Heinlein K, Fennell CT.

In: Developmental Psychology 2019 Feb 7. doi: 10.1037/dev0000699.


And one more: These authors reviewed neuroimaging studies of cognitive flexibility, with emphasis on set shifting and task switching. 

Title: Demystifying cognitive flexibility: Implications for clinical and developmental neuroscience.

Authors: Dajani DR, Uddin LQ.

In: Trends in Neurosciences 2015 Sep;38(9):571-8. doi: 10.1016/j.tins.2015.07.003.

Full text/author manuscript: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5414037/pdf/nihms709425.pdf