Postpartum maternal mood,feeding practices,and infant temperament in Barbados

Maternal mood, infant feeding practices, and infant temperament, using the Carey-R scales, were assessed in 226 healthy, well-nourished Barbadian mothers and their infants during the first 6 months of life. Maternal moods were assessed by self-report using the Zung depression and anxiety scales and a morale scale. Even after correcting for background variables, maternal depression and anxiety ratings and reports of despair at 6 months postpartum were significantly associated with infant temperament ratings at 6 months, using the original Carey-R scales, with factors derived from principal components analysis of the Carey items, and with summary difficulty scores. Maternal depressive symptoms were associated with decreased infant adaptability, reduced approach, negative mood and an increased sensory threshold. Infants of depressed and anxious mothers were more resistant to change and preferred constancy. These significant relationships were linear across the range of maternal mood scores and were not limited to diagnosed cases of depression or anxiety. In contrast, feeding practices were not significantly correlated with infant temperament, although infant difficulty on the temperament scales was associated with an increase in difficult feeding behaviors and with fathers’ involvement in the feeding of their infants. We conclude that interventions focused on improving maternal mood in the postpartum period are likely to impact positively upon maternal perceptions of their infants, with implications for improving child behavioral development and health in this underserved population.     

The rooting reflex as an infant feeding cue

Experts in infant health and development consider the rooting reflex a cue of a baby's hunger and recommend feeding the infant when this reflex occurs. However, the relation between rooting and infant feeding status has not been well established in the literature. In the current study, seven parents documented the occurrence of their newborns' rooting, crying, and a control reflex (palmar grasp) before, after, and between naturally occurring feedings. For all participants, rooting occurred during a greater percentage of reflex checks prior to feedings, whereas the palmar grasp occurred during a similar percentage of checks across these time periods. These results provide empirical support for the rooting reflex as a feeding cue. However, data for only one dyad suggested a high probability of the rooting reflex occurring without crying during prefeeding checks. Thus, our data do not provide evidence that feeding in response to the rooting reflex would preempt infant crying.     

Perception and recall of aversive material as a function of personality type

Relationships between personality dimensions of extraversion (E), neuroticism (N), psychoticism (P) and barrier (B) and patterns of psychophysiological responding during exposure to and subsequent recall of aversive and non-aversive material were investigated. Sixteen male volunteers were asked to recall the critical features of 10 film segments containing either neutral or aversive material. Heart rate (HR), skin conductance (SC) and electromyographic (EMG) responses were recorded throughout the session. Analysis showed that during exposure to aversive material, high BE Ss recorded high levels of autonomic responding and low levels of muscle tension, while during recall, they showed reduced autonomic activity and significantly higher levels of muscle tension. Low BE Ss showed significantly higher levels of muscle tension during film presentation and significantly lower levels during recall, with little change in autonomic reactivity between treatments. Recall data indicate that high BE Ss had significantly better recall under all conditions. N and P differences were unrelated to patterns of psychophysiological responding or efficiency of recall.     

Neonatal responsiveness as a function of maternal contact and obstetrical drugs

This work was designed to study changes in neonatal behavior during the first two days of life. Infants in Part I were from middle-class backgrounds. Half of these infants had unrestricted maternal contact during the first two days of life, the other half had contact with their mothers only at feeding time. Infants in Part II were from low socio-economic backgrounds. They were cared for entirely by the nursery staff during the first two days of life, so that differences in maternal style did not affect their behavior. Half of these babies were born to mothers who received 50 mg meperidine during labor, half to mothers who received no meperidine. This work provided evidence for the sensitivity of the neonate during the first two days of life. Both those infants who received unrestricted maternal contact and those whose mothers had received no obstetrical drugs exhibited more behavioral change than those who received low maternal contact or whose mothers had received meperidine during labor. High maternal contact and absence of obstetrical drugs also resulted in increased sensitivity to some environmental stimuli.     

Choice as a function of local versus molar reinforcement contingencies.

Rats were trained on a discrete-trial probability learning task. In Experiment 1, the molar reinforcement probabilities for the two response alternatives were equal, and the local contingencies of reinforcement differentially reinforced a win-stay, lose-shift response pattern. The win-stay portion was learned substantially more easily and appeared from the outset of training, suggesting that its occurrence did not depend upon discrimination of the local contingencies but rather only upon simple strengthening effects of individual reinforcements. Control by both types of local contingencies decreased with increases in the intertrial interval, although some control remained with intertrial intervals as long as 30 s. In Experiment 2, the local contingencies always favored win-shift and lose-shift response patterns but were asymmetrical for the two responses, causing the molar reinforcement rates for the two responses to differ. Some learning of the alternation pattern occurred with short intertrial intervals, although win-stay behavior occurred for some subjects. The local reinforcement contingencies were discriminated poorly with longer intertrial intervals. In the absence of control by the local contingencies, choice proportion was determined by the molar contingencies, as indicated by high exponent values for the generalized matching law with long intertrial intervals, and lower values with short intertrial intervals. The results show that when molar contingencies of reinforcement and local contingencies are in opposition, both may have independent roles. Control by molar contingencies cannot generally be explained by local contingencies.     

Effects of smoking and nicotine on EEG lateralization as a function of personality

The effects of nicotine/smoking on lateralization of the EEG were evaluated in 40 smokers while they responded to a low-stress, visual vigilance task. Smoking a high-nicotine cigarette was associated with a relatively larger increase in right hemisphere EEG arousal in extraverts and Type-A individuals, but with a relatively larger increase in left hemisphere EEG arousal in introverts and Type Bs. These findings suggest that nicotine/smoking may differentially influence the left and right hemispheres and that this interaction may be a function of personality.     

Choice for signalled over unsignalled shock as a function of shock intensity

Choice between a signalled shock schedule and an unsignalled one was examined at various shock intensities. Three rats were given the opportunity to change from the unsignalled schedule to the signalled one at intensity values between 0.15 mA and 1.0 mA. Steps were usually 0.15 mA and both ascending and descending series were given. For two other rats, shock intensity increased from 0.20 mA to 1.0 mA in 0.20-mA increments; for two additional rats, shock intensity was first 3.0 mA and was then reduced to 1.0 mA. Subjects tended to remain in the unsignalled schedule at the lower shock intensities, but spent most of each session under the signalled schedule at the higher intensities (1.0 mA and 3.0 mA). In addition, the time spent in the signalled schedule tended to vary systematically with shock intensity over at least part of the range of intensity values. It was concluded that the relationship between shock intensity and choice behavior is similar to the relationship between intensity and behavior in procedures involving avoidance, escape, and punishment.