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Investigations of caregiver-infant interaction have increasingly suggested a three pronged thesis about its structure, development and function: a) that such interactions conform to a hierarchically organized, rule governed exchange of message carrying displays (e.g., Stern et al., 1977; Tronick et al., 1979); b) that such exchanges evolve over time "shifting from a prominently biosocial to a more clearly psychosocial level" (Sander, 1977); and c) that it is within the ontogeny of this exchange that the precursors of adult communication are found (Kaye, 1977, 1979; Sander, 1977; Tronick et al., 1979). A central hypothesis of the first prong of this thesis is that caregiver displays which convey contradictory messages violate the rules governing the exchange and that such violations produce negative affect and disturbance in the infant. The goal of this project is to test this hypothesis and alternative hypotheses by evaluating the infants 1 response to simulated maternal depression using appropriate sequential analyses- This display presents the infant with powerful contradictory messages, and sequential analyses produce powerful descriptions of the quality of the infant's response to it

Summary When it comes to studying bilingualism and language acquisition in kids and infants, minimal pair-word learning is of particular importance due to this process being at play within a language and between languages. Having to discriminate between similar-sounding words within a language (i.e., dye & bye) and across languages (i.e., elephant & éléphant) is a complex task. The assumption that researchers have had since the early 1980s is that bilinguals may be better at certain aspects of word learning due to having to manage two languages concurrently. Previous studies have found mixed results regarding minimal pair word learning for both monolingual and bilingual groups depending on the ages. Discriminating between similar-sounding words is typically challenging before the age of 17 to 20 months regardless of the number of languages a child is learning. To investigate this question, we tested 19 participants between the ages of 14 and 18 months of age (14 monolingual and 5 bilingual). The level of attrition during the habituation trial or testing phase of the experiment made the data collection particularly difficult. Infants were recruited online from the Ottawa-Gatineau region and in Canada and the United States via a website for parents wishing to participate in various studies. During test trials, we recorded the looking time to the correctly and incorrectly labeled objects. Participants' performances were analyzed considering their language background, age, and socioeconomic status. Participants in the study were not able to discriminate between the two similar-sounding words regardless of their demographics. In conclusion, even while having access to visual cues from the speaker, monolingual and bilingual infants were not able to successfully learn similar-sounding words. Future studies should use a similar task using a live speaker via Zoom as opposed to a pre-recorded video to investigate whether the results would be different.

Thesis (M.S.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / Judgment methodology was employed to provide a qualitative description of mother/child interaction during infant play. Videoclips of 40 9-month-old infants in a free play situation with their mothers were rated by a panel of 10 judges using a series of 9 point Likert scales. Thirteen qualitative items, grouped into the five different areas of communication, coordination, engagement, affect, and overall quality of interaction, were rated from low or absent (0) to consistently high (8). Each mother/child dyad was assessed on two different segments. The reliability of the scales for assessing the mother/child interaction (mean ratings of 10 judges) ranged from .65 (mismatch) to .81 (mutual responsiveness) with an overall mean effective reliability of .77. There was a high intercorrelation among individual variables and overall quality of the interaction suggesting that no one of the rated qualities was more predictive of the overall mother/child interaction. Differences found in the rated quality of mother/child interaction between the two segments raise questions regarding the validity of conclusions about the overall quality of interaction based on a single short segment. Results are discussed in terms of the psychometric features of the scales and in terms of the mother/child interactional patterns. Suggestions for revising the methodology and the assessment tool are made to improve reliability and validity. More studies are necessary to validate the usefulness of the judgment methodology as an alternative approach to studying the quality of mother/child interaction. / 2031-01-01

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This thesis focuses on infant and maternal health through the examination of different government regulated policy interventions. Specifically, this thesis comprises of three essays. First, I examine the effect of a reduction in coal-fired power plant emissions on infant health outcomes of downwind counties. Second, I analyze how limiting lawyers’ contingency fees affects physicians’ decision to perform C-sections on women and, ultimately, its effect on infant mortality. The third, and final, paper investigates whether or not medical malpractice tort reforms have altered physicians’ decision to take part in defensive medicine. Chapter 1 examines the Clean Air Interstate Rule (CAIR) which mandated the reduction of power plant emissions in the eastern United States. This policy improved air quality in neighbouring downwind counties, greatly reducing exposure to a specific form of pollution—fine particulate matter. I investigate the impact of this reduction exposure on birth outcomes using data from the U.S. Natality Detail Files. I find that female babies experience improvements in premature birth and low/very low birth weight status which are driven by the reduction in prematurity. I also focus on full-term babies to better isolate the impact of prematurity from fetal growth on birth weight. Consistent with recent work, I find that full-term male babies experience an increase in birth weight, demonstrating an improvement in intrauterine growth due to lower exposure to fine particulates. Finally, I find a reduction in infant mortality for babies whose mothers were categorized as “high-risk” pregnancies, suggesting that reduced exposure may lead to improved birth outcomes among those most at risk. Chapter 2 analyzes a limit on contingency fees for lawyers in medical malpractice cases enacted in Nevada. Generally, such limits are thought to change the composition of liability cases as they induce lawyers to drop more frivolous cases in favour of ones involving death and serious injury. Inadvertently, obstetricians faced a greater fear of litigation. Applying synthetic control methods, I find a 2.8 percentage point increase in the C-section rates of high school dropout patients, translating to a ten percent increase after the reform. There is no statistically significant difference in C-section rates after the enactment of the reform on patients with at least a college degree, and further, no statistically significant effect on infant mortality. Limiting contingency fees in medical malpractice cases induces obstetricians to engage in defensive medicine by performing more C-sections on low income patients, illustrating that tort reform can alter physician procedural patterns, albeit in heterogeneous ways. Chapter 3 continues with the theme of government regulated policy intervention by examining the effects of medical malpractice tort reform on maternal and infant health. Numerous papers examined the effects of tort reforms on physician behaviour using data from the 1990s. However, a medical malpractice “crisis” in the early 21st century saw many US states adopt tort reforms to alleviate this issue. Using data from 1995 to 2012 I observe that tort reforms are not as effective as they once were. However, I find evidence that physicians’ procedural choices are affected by tort reforms. Not only are C-section rates and “preventable” complications affected by tort reforms, but I also observe that tort reforms influence physicians’ decisions with non-risky patients. / Thesis / Doctor of Philosophy (PhD)

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The present study provides information about the relationships between parental reactions to their children‘s expression of negative emotions at 8 months, parent-infant attachment at 12 and 15 months and parental reactions to children‘s negative emotional expressions at 24 months, and as well as the extent to which all of these variables predict children‘s emotional expressivity as toddlers at 24 months, after controlling for infant emotional reactivity. Analyses showed that parental responses to infant negative emotions, insecure attachment and parental responses to toddlers‘ negative emotions as well as infant emotional reactivity all made independent contributions to predicting toddler negative (vs. positive) affect. Only insecure infant-parent attachment, not parental socialization or infant emotional reactivity, predicted toddler flat (vs. expressive) affect. The inclusion of fathers in this study is important not only to clarify how mothers and fathers differ in socializing their children‘s negative emotions, but also to have a more complete study of how emotional expressivity develops. Analyses conducted separately by parent gender revealed differences in the relationship between parental socialization, attachment and emotional expressivity across mothers and fathers, indicating that researchers should continue to include fathers in studies of socialization of emotional expressivity. / text