The vestibular system of the inner ear detects head position using three orthogonally oriented semicircular canals. Vestibular function relies on precise canal shape and orientation, and slight changes can cause vestibular defects. Canals are sculpted from pouches that protrude from the otic vesicle, the simple sphere of epithelium that forms the inner ear. In the center of each pouch, a "fusion plate" forms where cells lose their epithelial morphology and the basement membrane breaks down. The opposing layers of the fusion plate intercalate and are subsequently removed, creating a canal. Proper fusion depends on Netrin-1, which regulates basement membrane breakdown during fusion in mice, although the underlying molecular mechanism is unknown. This dissertation describes our work to better understand the cellular effects of Netrin-1 during canal formation. Although vestibular apparatus structure is shared among species, some developmental events that lead to this structure differ. For example, while fusion plate basement membrane breakdown is conserved, apoptosis is required for fusion in chicks, but not in mice. We used gain-of-function approaches to determine the main cellular effect of Netrin-1 during fusion in chicks and mice. We show that overexpression of Netrin-1 in chicks prevents canal fusion from occurring normally by interfering with apoptosis. On the other hand, we show that ectopic expression of Netrin-1 in mice using a conditional expression allele causes excessive fusion, resulting in canal truncation. This suggests that Netrin-1 may play divergent roles during canal morphogenesis in chicks and mice. To determine if Netrin-1 regulates the basement membrane in other contexts, we created a Netrin-1 conditional null allele. This was necessary because existing Netrin-1 mutants express residual Netrin-1 protein, which could be sufficient to rescue basement membrane defects in other tissues, and because existing mutants die shortly after birth, preventing postnatal analysis. Complete loss of Netrin-1 protein in our newly generated mice does not cause more severe defects in fusion compared to existing Netrin-1 hypomorphs, suggesting that residual Netrin-1 protein does not affect the basement membrane during fusion in Netrin-1 hypomorphs. Future work will determine if complete loss of Netrin-1 affects basement membrane integrity in other tissues.

In order to break the cycle of poverty for disadvantaged children through early intervention, a counseling component is needed. As perceived by parents and teachers, counseling services would reduce the long-range damaging effects caused by social problems such as crime, violence, and drugs. This study attempted to determine the counseling needs of three- to five-year-old educationally disadvantaged children. The research method was descriptive and used a questionnaire. The survey questionnaire was administered to a sample of 22 parents and 22 teachers at a Head Start facility. Survey respondents were 44 African-American subjects: 1 male and 43 female teachers in Atlanta, Georgia. In conclusion, a counseling model was proposed to implement subsequent results of this study.

<p> Using a meaning making lens and a qualitative methodology, this dissertation study sought to explore transformative meaning making and implicit beliefs of parenting among a sample of 40 adolescent mothers participating in a home visiting program during their transition to parenthood. Given the high attrition rate for interventions serving adolescent moms, the study also explored the alignments between meaning making and home visiting program participation. Through iterative coding and theme analysis, this investigation revealed that participants&rsquo; beliefs about parenting evolve as they transition from pregnancy to parenting. They engage in meaning making throughout the process, which leads to scripts of change in three areas: improvements in relationships, changes in life outlook, and changes to self. Two groups emerged on either end of the spectrum of meaning making. High meaning-making <i> transformers</i> tended to remain actively enrolled in the intervention while the low meaning-making <i>remainers</i> all dropped out by the second year. An analysis of implicit beliefs about parenting, or meta-parenting mindset, identified three groups of participants: <i>fixed theorists, </i> <i>incremental theorists,</i> and <i>mixed theorists. </i> Fixed theorists, who believed parenting ability was natural or instinctual, had a lower retention rate in the program (14%) than the overall rate of the sample (42%) even after controlling for participants who moved away. Incremental theorists, who attributed their parenting abilities to gradual growth and learning, had a 50% retention rate and also represented just 6.6% of those receiving a low number of visits and 66.6% of those who had high rates of home visits.</p>

The present study assessed the relationship between one's attachment style and one's chronic (trait-based) and acute (state-based) emotional responses to others, focusing on one's level of empathic concern. The individual attachment styles of subjects were assessed using the Brennan, Clark and Shaver (1998) Experiences in Close Relationships Scale. In the first part of the project, participants' emotional responses were assessed when confronted with another individual in need in an experiment based on the Batson et al. (1988) "Katie Banks" paradigm. "Katie Banks" is a fictitious student who needs help raising money to assist in taking care of her orphaned siblings. This experimental paradigm was used to measure participants' affective responses to learning of her plight. The second part of the project involved an assessment of the trait of empathy as related to individuals' attachment styles. The participants completed the Davis (1996) Interpersonal Reactivity Index (IRI) to assess four sub-measures of empathy. Potential links between these measures and attachment style were explored. The primary hypotheses were that individuals with attachment styles characterized by a tendency to focus on others would be more able to express other-focused emotional responses to another in need (and in general) than those individuals who tend to focus on themselves and generally avoid relationships. In addition, those individuals who typify attachment styles that tend to become anxious within relationships were predicted to express more distressing emotional responses than those who represent attachment styles with less anxiety within relationships. Whereas some of the results from the trait assessment of empathy supported these hypotheses, results of the state-based affective responses did not. With regard to trait-based measures, securely attached individuals tended to take the perspective of others more than less securely attached individuals, and secure individuals expressed significantly less distress. In addition, preoccupied individuals (and high anxiety individuals in general) exhibited significantly more distress. Finally, those with low avoidance attachment styles responded significantly higher on the fantasy scale. With regard to the state-based measures, contrary to predictions, there were no differences among the attachment styles in the type of affective responses to the laboratory need situation.

Previous genetic research has identified many human genes with allelic variation that are associated with differences in hormone synthesis. Still other non-genetic biological research has shown that increased levels of hormones are predictive of onset of puberty and that pubertal maturation is one of the strongest predictors of sexual activity onset. Studies informed by evolutionary theory have also shown that family context, such as the presence or absence of the biological father in early childhood, can predict pubertal maturation and, indirectly, subsequent sexual activity. This study was unique in that no research to date had attempted to use genetic markers as direct predictors of pubertal maturation and subsequent onset of sexual behavior in adolescents. Two genes of particular interest included the androgen receptor (AR) gene and the cytochrome P450c17-alpha gene (CYP17). Saliva samples (for genetic marker identification), pubertal status, and sexual behavior measures were gathered bi-annually from 248 post-menarcheal females over 2--3 years. Hierarchical linear modeling and growth curve analyses revealed that the A1/A1 allele of the CYP17 gene was predictive of the presence of a biological father, which predicted age at menarche. Later ages at menarche predicted lower onset level of sexual development and earlier ages at menarche predicted higher onset levels of sexual development; however, lower onset levels of sexual development predicted faster rates of sexual development. These findings show that genetic markers can be used to help identify variation in timing of pubertal development. Also, these results provide additional insight into understanding the differences in rates of sexual development among girls and suggest that there are mediating factors that may be buffering girls with higher onset levels of sexual development from progressing through sexual stages faster.

Sexual identity is examined in terms of three distinct parts: sexual style, self-concept in relational and sexual domains, and concepts of relationships and partners. Sexual style, the first component of sexual identity in this study, is defined operationally to include numerous features of sexual behavior and attitudes about behavior. Self-concept in relational and sexual domains is the second component of sexual identity and includes beliefs about the self in relationships, desire for relationships, personal marriage expectations and gender role beliefs. Concepts of relationships and partners, the third component of sexual identity, includes features of dating relationships in general, beliefs about dating, experience of communication and violence in relationships, and for people in relationships, specific characteristics of the relationship. The data for this project were taken from Wave 7 (age 20-21) of the Michigan Study of Adolescent Life Transitions (MSALT). Part one of the study utilized hierarchical cluster analysis with split halves of females and males to group individuals into different sexual style clusters. Clusters were based on the measured variables: Usual frequency of intercourse, importance of regularly having sex, satisfaction with sex life, experience of coercion for sex, and sexual risk reduction. For females, the following five-cluster solution best represented the sample: Satisfied, Moderate, Active Unprotected, Pressured and Comfortably Inactive. For males, the following six-cluster solution best represented the sample: Satisfied, Dissatisfied, Moderate, Active Unprotected, Pressured and Comfortably Inactive. The model to predict sexual style was based on a model of sexual identity, and used multivariate logistic regression to estimate the probability of cluster membership given a certain level of each predictor variable, holding constant the other predictor variables. Using the model of sexual identity, it was possible to correctly classify between 35--47% of the females and males into the correct sexual style.

The study attempted to explore if epistemological development occurs among first-year college students and to untangle the process of that development by investigating the role of intersubjectivity and metacognitive awareness as mechanisms of change. Epistemological development is an orderly sequence of five increasingly complex positions through which students reason about the nature of knowledge (Perry, 1970). Intersubjectivity is the cognitive developmental process whereby interacting peers who begin problem-solving tasks with different understandings arrive at shared understanding in the course of communication with each other (Tudge, 1992). Metacognitive awareness, the ability to facilitate the control aspect of cognition (Schraw & Dennison, 1994), may play an important role in the resolution of ill-structured problems (Kitchener, 1983). Eighty-three participants (treatment N = 50; control N = 33) completed the Measure of Epistemological Development, an open-ended paper-and-pencil five-domain instrument which was created for this study (Baxter-Magolda, 1987; Moore, 1990) and administered at pre-test, post-test, and follow-up. The developmental process variables were measured by self-report intersubjectivity items (i.e., exposure to new forms of reasoning; adopted others' reasoning) and the Metacognitive Awareness Inventory Regulation of Cognition Sub-Scale (Schraw & Dennison, 1994). Treatment group discussions about ill-structured problems were guided by seven probe questions (Kitchener & King, 1981), offered scaffolding and contextual support (Kitchener, Lynch, Fischer, & Wood, 1993), and ended with peers reaching agreement. Epistemological reflection developed significantly between pre-test and follow-up (t = -2.60, p < .01). The control group changed little over time, while the treatment group slightly regressed from pre-test to post-test then developed significantly by follow-up F(df = 2, 7.06, p < .01). Intersubjectivity moderated change in epistemological reflection between pre-test and follow-up (R² = .645, p < .05). Treatment participants who reported the lowest levels of intersubjectivity scored higher on follow-up epistemological reflection than all other treatment participants. Metacognitive awareness moderated change in epistemological reflection differentially for treatment and control participants. The unique effects of the metacognitive-awareness-by-condition interaction term and metacognitive awareness remained after the effects of pre-test epistemological reflection, metacognitive awareness, and the pre-test-by-metacognitive-awareness-by-condition interaction term were controlled statistically (R² = .532, p < .05).

The purpose of this exploratory study was to provide insight into the contextual influences (events, experiences, and relationships) that impact multidimensional identity development during college. Specifically, the types of influences that shape identity development and the processes by which this development occurs were of interest. The sources of data for this study included the stories told by college alumni as well as the concepts found within commonly used student development inventories and assessment tools. Two methods were used to gather data from the respondents: lifelines and semi-structured interviews. The lifeline was used to encourage reflective thought among the alumni; whereas, the interviews were used to gather information about their experiences during college. A document analysis was conducted on the student development inventories and assessment tools in order to determine the conceptualization of identity found therein. In interpreting the data, a conceptual framework that drew on two bodies of literature (the research that concerns student identity development and the research that focuses on life events and experiences) was used. The results of the current study not only provide insight into the contextual influences that shape multidimensional identity development but also suggest the importance of embracing a constructivist framework and holistic conceptualization when studying identity development. Moreover, the results suggest new ways of thinking about the influence that faculty and administrators have over the environment in terms of shaping identity. Future research should continue to investigate the underlying process of multidimensional identity development.

Attention is one advanced skill in the field of neuropsychology which is associated with the frontal lobe of the human brain. As there have been many studies supporting the idea that sexually abused children demonstrate attentional deficits (Williamson, Borduin, & Howe, 1991; Putnam, 1993; Mennen, 1994; Maynes, 1994), the current study sought to assess attentional deficits in sexually abused children, and then establish any relationship linking child sexual abuse (CSA) and neuropsychology. Victims of sexual abuse have also been found to demonstrate higher levels of anxiety than non-sexually abused children (Conte & Schuerman 1987; Briere & Runtz, 1988; Heibert-Murphy 1992; Mennen & Meadow, 1994; Trickett & Putnam, 1994b). Secondarily, this study examined level of anxiety, in an effort to determine whether the children's attentional problems could be related to high anxiety level. Both the neuropsychological ability to sustain attention and self-reports of level of anxiety were examined in a group of thirty children, fifteen of whom had been sexually abused and fifteen who were reported to be non-sexually abused, for the purpose of learning whether any differences would be discovered between the two groups. Sustained attention was measured through three different assessment instruments: the Wisconsin Card Sorting Test, the Mazes subtest of the Wechsler Intelligence Scale for Children - Third Edition, and the Trail-Making Test, Parts A and B. Anxiety was measured by the children's self-reports of anxiety on the Revised Children's Manifest Anxiety Scale. Although trends of greater perseverative responses to attentional tasks were found in the sexually abused group, no significant main effects for group were found on the neuropsychological test performance. Similar to the findings of previous research studies, the sexually abused group displayed significantly higher levels of physiological anxiety, worry/oversensitivity, and social concerns. Present findings seem to suggest that attentional difficulties in sexually abused children may be more related to emotional than neuropsychological difficulties.

The purpose of this project was to investigate which spatial and physical object properties 9-month-old infants would use to trace an object in time and space. The particular object characteristics of interest were size, location and features. A two-location task was used, with looking time as the dependent measure. Infants observed a small toy troll, which was subsequently occluded. When the two flaps were removed, the infants observed either a standard or a change event. During the standard event no change occurred (the small troll was revealed at the same location). During a change event, some sort of physical or spatial change took place; the object might have changed its size (the large troll was revealed at the same location), its location (the small troll was revealed at the other location), its features (the small bear was revealed at the same location), or some combination of these attributes. Infants only observed one type of change event, depending on which of the seven conditions they were assigned to. The findings from this study can be interpreted in terms of two default assumptions: the Same Location/Same Object Rule and the Different Location/Different Object Rule. Nine-month olds use size cues to inform them about object identity in both situations; additionally, they use featural cues to inform them in the second case.