Reinforcement from the sucking environment and subsequent modification of sucking behavior in the human neonate

The reinforcing aspects of sucking behavior in 36 human newborns was examined in a limited instrumental conditioning paradigm where sucking was both operant and reinforcer. During training, response density (rate based on sucking opportunity time) and latency were measures of two components of nonnutritive sucking, contingent negative pressure suction, and incidental jaw movement. The strategy for determining the reinforcing aspects of sucking involved comparisons of three types of sucking stimuli as reinforcers. The nature of modified operant sucking was investigated during extinction by examining number of sucks per burst, number of bursts emitted, and interburst interval time. The feedback from sucking which acted as reinforcement was concluded to be response density. Sucking was modified by changes in pausing behavior, including response latency and pauses between bursts of sucks. The number of sucks per burst also showed a significant change under certain conditioning arrangements.     

The quality of sucking in infants with colic

Feeding problems have been reported in infants with colic. The purpose of this study was to examine the nutritive sucking pattern of infants identified as having colic. Twenty-nine infants (16 with colic and 13 controls) between the ages of 1 to 3 months, being bottle-fed by their mothers, were observed by a blind examiner. We hypothesized that infants with colic would show greater disorganization in nutritive sucking and show greater variability in sucking rate than infants without colic, as assessed by the revised Neonatal Oral Motor Assessment Scale (NOMAS). Infants with colic were found to present a disorganized sucking pattern; namely, a lack of rhythmical movement and a difference in amount of sucks per burst than infants without colic. Methods of intervention are suggested.     

Analysis and treatment of finger sucking

We analyzed and treated the finger sucking of 2 developmentally typical children aged 7 and 10 years. The functional analysis revealed that the finger sucking of both children was exhibited primarily during alone conditions, suggesting that the behavior was maintained by automatic reinforcement. An extended analysis provided support for this hypothesis and demonstrated that attenuation of stimulation produced by the finger sucking resulted in behavior reductions for both children. Treatment consisted of having each child wear a glove on the relevant hand during periods when he or she was alone. Use of the glove produced zero levels of finger sucking for 1 participant, whereas only moderate reductions were obtained for the other. Subsequently, an awareness enhancement device was used that produced an immediate reduction in finger sucking.     

Neonatal sucking: Effects of quantity of the response-contingent fluid upon sucking rhythm and heart rate

The temporal organization of neonatal nutritive sucking and heart rate were studied in two consecutive 4-min periods to analyze the effects of two quantities of response-contingent fluid. One group of newborns experienced only the larger amount, a second experienced the smaller, and two other groups experienced both in counterbalanced order. Cumulative pausing time and intersuck intervals (sucking rate within bursts) were both affected by the amount of fluid delivered at each response. At the start of sucking bursts, heart rate accelerated to a stable level. Within-burst heart rates were higher with increased quantity of contingently delivered fluid. The results are discussed in relation to the distinction between nutritive and nonnutritive sucking and to previous findings on the effects of fluid sweetness upon sucking.     

Microcomputer measurement and analysis of newborn sucking

An on-line Basic computer program with on-line monitor prompts and read-out collects, stores, and digitizes pressure and latency of sucking responses for later analyses. The program and analog equipment are described, and approximate costs are noted.     

The organization of non-nutritive sucking in the premature infant

Changes in non-nutritive sucking contingent upon the repeated presentation of unpatterned and patterned light stimulation were examined in a sample of 18 premature infants. Stimulus contingent sucking change in chronologically younger infants tended to be somewhat shorter in duration than that of the chronologically older infants and showed stimulus contingent sucking acceleration as well as suppression. Evidence was also found for less orienting among infants showing abnormalities in their sucking behavior. No evidence for habituation was found in any subgroup. Possible factors contributing to the strength and nature of stimulus contingent non-nutritive sucking changes in infants are discussed.     

Neonates' heart rate,sucking rhythm,and sucking amplitude as a function of the sweet taste

In previous studies of human newborn sucking, the effects of increasing fluid sweetness and/or volume included a decrease in sucking rate within sucking bursts and, paradoxically, an increase in heart rate. To determine whether the heart rate increase can be attributed to increased sucking amplitude for sweeter fluids, sucking and heart rates of 20 full-term infants were studied. Half sucked for three consecutive 2-min periods, first receiving small drops of water for each suck, then no fluid, then 15% sucrose. The other half experienced the reverse order. The results for sucking and heart rate were consistent with previous studies; sucking rates within bursts were slowest for sucrose and fastest for no fluid. Heart rate was higher for sucrose than for the other fluid conditions, however, only in the water-first group. The heart rate increase was significant on statistical tests which controlled for sucking amplitude as well as for several other motor variables. Sucking amplitude itself varied with fluid sweetness in the water-first group only, in which it was highest for water. There were more total sucks, longer sucking bursts, and less time between successive bursts under the sucrose condition. Multivariate statistics helped establish a set of dependent variables—sucking rate within bursts, total number of sucks, and heart rate—which most parsimoniously describes the effects of fluid sweetness. A hedonic explanation of the response of newborns to sweetness is thus reiterated.     

Differential sucking by neonates of depressed versus non-depressed mothers

Forty-two neonates (M = 39-h old) of depressed and non-depressed mothers sucked on cold (50 °F) and warm (78 °F) nipples on alternating trials. Half the infants received the cold nipple on the first of the eight trials (20 s each) and the other half received the warm nipple first. Neonates of depressed mothers sucked twice as much as neonates of non-depressed mothers, suggesting arousal dysregulation, overactivity or greater hedonic behavior in the newborns of depressed mothers. Although the newborns did not show a preference for cold or warm nipples, a temperature order effect revealed that neonates who received the cold nipple on the first trial sucked significantly more on trials 2–8 than those who received the warm nipple on the first trial, suggesting that an initially cold nipple might elicit greater sucking. More research is needed on maternal mood effects and temperature of objects to determine how these factors affect neonatal sucking behaviors.