For many decades, the impact of artificial nipple use on feeding skills in breastfeeding infants has been measured in studies on breastfeeding duration, measuring rates of exclusive breastfeeding duration and/or the duration of the entire breastfeeding course (see Appendices 1 - 6 in the Resources section of this website). Skill acquisition, skill decay, and re-acquisition of infant breastfeeding skills can also be studied and measured in real time, i.e., in milliseconds (ms), utilizing the parameters below during direct observation of infant feeding behaviors.
Similarly, in bottle-feeding populations - regardless of whether the milk is expressed mother's milk, human donor milk, or artificial infant milk - the acquisition of bottle-feeding skills, skill decay, and the re-acquisition of infant bottle-feeding skills can also be measured in regard to task-switching between different styles of artificial nipples that vary in diameter, length, texture, shape/contour, scent, and taste. Task-switching between similar yet different pacifiers/dummies can be studied as well. Task-switching is much studied in the cognitive sciences, including the subsequent and frequent switch costs of decreased speed and accuracy for the task.
Reaction time (RT): the interval between the presentation of a stimulus and the initiation of a response, measured in milliseconds (ms). After a newborn’s learning experience with an artificial nipple and subsequent return to the maternal breast, a delay in the infant's reaction time to the maternal stimuli (nipple-areolar complex) is often observed.
Movement time (MT): the interval of time between the initiation of a movement and its completion, also measured in milliseconds. Following an infant's learning experience with an artificial nipple and subsequent return to the maternal breast, the infant’s movement time for achievement of the oral grasp and/or effective suckling at the breast is often prolonged.
Response time: the interval from the presentation of a stimulus to the completion of a movement; the sum of reaction time (RT) and movement time (MT).
The equation: RT + MT = response time.
Inhibition of return (IOR): the phenomenon of the delay or impairment in responding
to a previously cued (orienting) stimulus (by 500 - 3000 milliseconds [ms] or more).
*1 second (s) = 1000 milliseconds (ms)
The above learning terms can also be utilized to further define infant feeding confusions and preferences, expanding on the first formal definition of nipple confusion provided by Neifert, Lawrence, and Seacat (1995).