This dissertation investigates high school students' drug use and the variables identified as risk factors for such use. Specifically, the purpose of this research was to analyze drug use data with regards to levels of Subjective Distress, Parental Bonding, Parental Supervision, and Sensation Seeking, to understand how experimental marijuana users experience these risk factors when compared to other types of drug users. This research posits that experimental marijuana use may be more reflective of adolescent development than of pathology. The theoretical construct underlying this research is the perspective that certain behaviors are deemed harmful based more on moral judgments and the social construction of risk as opposed to the actual danger the behavior poses for the individual. This research used data from a cross-sectional survey given to high school students from a New England college town. Statistical analyses was conducted on the responses of a quantitative, Likert style survey which included 452 questions all derived from existing national surveys. The survey was voluntary and administered to 993 students in grades nine through twelve in January of 2000. The results indicated that a simple, stepwise progression between the level of drug use and the risk factors Parental Bonding, Parental Supervision, and Subjective Distress did not exist. In most cases, experimental marijuana users were more like abstainers than other drug users. The relationship between Parental Supervision and drug use was more related to an adolescent's age than to the actual supervision. Consideration of gender differences revealed that the genders experience the risk factors, specifically parental bonding, differently. Females, when compared to males, did not experience as strong a relationship between parental bonding and drug use. The application of a quadratic regression equation revealed that males' relationship between drug use and parental bonding was more complex; moderate levels of parental bonding predicted drug use more strongly than low levels of parental bonding. The results suggest that future research must be more sophisticated in its analyses of drug use and adolescents, considering the developmental stage of the adolescent, the type of drug used, and questioning the assumption that experimental marijuana use is unequivocally harmful.

The main objective of this dissertation was to characterize the tool-using ability of rhesus monkeys and children by examining the acquisition and comprehension of tool-using behavior, and by identifying factors that might be related to individual differences in the ability to use tools. The first study examined whether twenty rhesus monkeys could use a rake to extend reach, whether they understood the required properties of the tool, and whether tool-using ability was correlated with behavioral characteristics. Fifteen monkeys used the rake to retrieve treats placed out-of-reach; however, none of the monkeys tested selected an effective rake from an ineffective rake. The level of tactile oral exploration in non-tool-using contexts was positively correlated with the number of rewards retrieved. The second study examined whether rhesus monkeys could use a rod to insert and probe and whether they understood the effects of using the tool. Only two monkeys used a rod to push a reward out of a clear tube. Subsequent manipulations involving multi-tube combinations, in which only one tube was baited, indicated that the monkeys were unable to select the correct path or tube. However, these monkeys correctly selected the baited tube over empty tubes when the tubes were presented on separate walls. The third study examined whether rhesus monkeys and 36-month-old children were able to use two different tools in series to retrieve a desired object. Both of the two monkeys tested used a rake to retrieve a rod and then used the rod to push a reward out of a clear tube, and all but one of the children tested used the tools in series either on their own or following hints or demonstrations. The fourth study revealed that certain types of object manipulation and behavior were related to tool-using ability in monkeys. In summary, this dissertation characterized tool-using in rhesus monkeys and children, validated new procedures for assessing comprehension in tool-using tasks, and identified certain factors related to individual differences in tool-using ability. The implications of these results are discussed.

Handedness is a widely studied behavioral asymmetry that is commonly measured as a preference for using one hand over the other. Right hand preference in humans occurs at a ratio of 9:1, whereas left hand preference in rhesus monkeys has been estimated at 2:1. Despite differences in the direction and degree of hand preference, this dissertation investigated whether primates share common underlying factors for the development of handedness. Previous work in human infants has identified a predictive relationship between rightward supine head orientation and later right hand preference. Experiment 1 examined the relationship between neonatal head orientation and later hand use in rhesus monkey infants (N=16). A leftward supine head orientation bias was found that corresponded to greater left hand activity for hand-to-face movements while supine; however, neonatal head positioning did not predict later hand use preference for reaching or manipulation on a coordinated bimanual task. A supine posture is common for human infants, but not for rhesus monkey infants, indicating that differences in early posture experience may differentially shape the development of hand use preference. Movement quality is an additional factor that may affect how the hands are used in addition to neonatal experience. 2-D and 3-D kinematic analyses were used to examine the quality of reaching movements in rhesus monkey infants (N=16), human infants (N=73) and human adults (N=12). In rhesus monkey infants, left hand reaches were characterized as ballistic as compared to right hand reaches independent of hand use preference (Experiment 2). Left hand ballistic reaching in rhesus monkeys may be a carryover from earlier primates that relied on very fast reaches to capture insect prey. Unlike monkey infants, reach quality was a function of hand preference in human infants (Experiment 3). By contrast, a right hand advantage for reaching was observed in human adults regardless of left or right hand preference (Experiment 4). Differential hand experience due to hand preference in early infancy may in part be responsible for the hand preference effects on movement quality observed in human infants but not monkey infants. Motor control may become increasingly lateralized to the left hemisphere over human development leading to the right hand advantage for reaching observed in human adults, as well as over primate evolution leading to right hand use preferences in higher primates like chimpanzees. An underlying mechanism such as a right shift factor in humans and a left shift factor in rhesus monkeys may be a common basis for primate handedness. Environmental and experiential factors then differentially shape this mechanism, including species-typical development. Further work examining the ontogeny of hand preference and hemispheric specialization in various primate infants will lead to a greater understanding of how different factors interact in the development of hand use across primate species.

One of the many ways that the ubiquitously expressed Polycomb Group protein, Yin-Yang1 (Yy1), is believed to regulate gene expression is through direct binding to DNA elements found in promoters or enhancers of target loci. Additionally, YY1 contains diverse domains that enable a plethora of protein-protein interactions, including association with the Oct4/Sox2 pluripotency complex and the Polycomb Group silencing complexes. To elucidate the in vivo role of YY1 during gastrulation, Yy1 was deleted in the epiblast of mouse embryos using Sox2-Cre. Yy1 conditional knockout (cKO) embryos initiate gastrulation, but the primitive streak fails to extend anteriorly. Migration through the streak is severely impaired, and streak descendants fail to downregulate E-Cadherin resulting in an aberrant accumulation of streak cells. Intriguingly, we find an accumulation of Nodal and a concomitant reduction of Nodal antagonists suggesting that YY1 is normally required for proper Nodal regulation. We have observed that definitive endoderm is specified but fails to properly delaminate into the outer layer and mutant embryos also fail to accumulate any axial midline structure. Although anterior neuroectoderm is clearly specified, mesoderm specification is severely restricted. Our results reveal critical requirements of YY1 in several important developmental processes, including epithelial to mesenchymal transition (EMT), Nodal regulation and PRC2 mediated H3K27Me3 of the inactive X-chromosome. Despite the localization of Oct4 and Sox2 transcripts in the neuroectoderm of the Yy1 epiblast cKO and the presence of stable transcripts of both genes in the Yy1 RNAi knock down blastocyst, both proteins are void in these models and Oct4 protein is absent in the peri-implantion Yy1 KO mouse. We believe YY1 is required for stabilization of the Oct4/Sox2 pluripotency complex in vivo. We have identified two endogenous forms of YY1 and we believe these posttranslational modifications of YY1 permit the protein to perform the diverse activities it performs in vivo. For example, in addition to the roles in transcriptional regulation and protein complex stabilization, we have also observed a role in YY1 in epigenetic regulation in vivo, including deposition of histone 3 lysine 27 trimethylation (H3K27Me3) on the inactive X-chromosome in female embryos and a role in imprinted gene expression of the Dlk1/Dio3 locus. Detailed analysis of the peri-implantation lethal Yy1 KO mouse in utero revealed unexpected novel developmental events. A large scale follow up examination of wildtype implantation primarily through analysis of immunohistochemical data and gene expression profiling at the cellular level. We analyzed expression patterns of important developmental genes including Oct4, Sox2, Nanog, Cdx2, Gata6 and Sox17, as well as markers of epithelial biogenesis including ZO1, E-Cadherin and Laminin. Interestingly we identified consistent variances in cell populations within the ICM as well as likely primitive endoderm progenitors that produce Laminin and first appear at the periphery of the ICM. We also identified a novel upregulation of Sox17 specifically at the site of implantation. With these data we compose a staging diagram of peri-implantation embryonic and maternal changes during the elusive window of development. These results are the first to elucidate the role of YY1 during gastrulation and peri- implantation, providing potential in vivo targets of YY1 and highlighting the diversity of function of YY1 in the early embryo. Additionally we have been able to advance molecular knowledge of peri-implantation development, in order to provide a platform from which to analyze other peri-implantation lethal KO mice, as well as to aid biomedical understanding of implantation and implantation failure in mammals.

Perspective-taking skills are central to the successful navigation of social situations. Children need perspective-taking skills to help them correctly interpret different cues and accurately assess social situations so they can determine how to best respond. Children with Autism Spectrum Disorders (ASD) exhibit marked impairments in this area. In order to develop successful social skills interventions for this population, it is critical that we have a strong understanding of the nature of their deficits. While there is robust evidence that children with ASD experience difficulty making inferences about the beliefs of others, research on their ability to infer emotions has had more mixed results (Baldwin, 1991; Baron-Cohen, 1991; Happe, 1994; Hillier and Allinson, 2002; Kaland et al., 2005; Joliffe & Baron-Cohen, 1999; Serra et al., 2002; Williams & Happe, 2010). This study examined how well children with autism spectrum disorders are able to make emotional inferences using three different measures of emotion attribution. The measures were administered to a clinical sample of participants with high functioning-autism spectrum disorders (HF-ASD) and a comparison sample of typically developing participants to determine whether individuals with HF-ASD experienced more difficulty making emotional inferences from different cues than their typically developing peers. The hypotheses that children with HF-ASD make fewer spontaneous emotional inferences and have lower levels of emotional awareness than their typically developing peers were also tested. Finally, performance on these emotional inferencing measures was examined to determine whether they were able to reliably discriminate between participants with different levels of autism-related symptomatology. Participants with autism performed as well as their peers on all measures of emotion attribution in this study. These findings and their implications are explored.

The purpose of the study is to describe the development of infant melatonin levels form birth to six months, and to examine the effects of seasonal luminosity, and nutrition on the development of melatonin levels and changes in circadian sleep:wake cycles. Additionally the study will investigate the role of infant, maternal and care giving variables on the development of infant sleep. This longitudinal study will be conducted in Tromso, Norway, which, because of its far northern location (70° North), provides extremes in seasonal variations and light/dark cycles. For two months in the Winter the sun never rises above the horizon and for two months in the Summer it never sets below the horizon. A total of 146 infants (ranging in age from birth to 6 months) and 146 mothers participated in the study. Four sampling periods occurred within a two week interval surrounding the Summer and Winter solstices and the Spring and All equinoxes. Results show that age is the primary developmental influence and seasonal light influences actual levels of development at three and six months of age.

An individual's social identity development in pluralistic societies going through an integration process has been little understood. A study was conducted on the Lebanese individual's social identity development. Based on a study of the theories of the psychology of social identity development, four Lebanese Identity development stages were proposed where an individual's social identity progresses from an unintegrated Lebanese, sectarian group identity, towards a more integrated Lebanese Identity. To test the validity of these stages, two research studies, a qualitative and a quantitative study, were conducted to explore the Lebanese social identity. In the qualitative study, open ended interviews of a number of Lebanese community leaders were conducted and analyzed. While the four proposed identity stages were reflected in the subjects' views, the majority of their views reflected a higher stage of identity development where the emphasis was on a civic society and the satisfaction of the individual's rights and needs as a basis of the integrated Lebanese social identity. These results were in agreement with the proposed Lebanese Identity development stages. Moreover, a quantitative research study examined the relationship between an individual's various socio-economic factors and their level of identity development. The results revealed that there is a strong relationship between an individual's level of identity development and the following socio-economic variables: Sectarian identity, profession, level of education, source of data collection, and nature of dual Lebanese nationality. In general, it was concluded that individuals had higher levels of Lebanese Identity development when they enjoyed a more secure life, had higher levels of communication and exposure to others in society as well as higher levels of education.

This study examined the role of the coping process as a mediator of the long-term psychological adjustment of survivors of childhood sexual abuse, with a focus on three specific areas of coping: self-criticism, support seeking behavior, and disengaged coping. The study also addressed a limitation of the existing research in this area by controlling for the potentially confounding effects of depression through the use of a control sample that was matched for the level of depressive symptomatology. Fifty-one undergraduate women with a history of childhood sexual abuse and eighty-eight nonabused undergraduate women completed the Depressive Experiences Questionnaire, the Coping Strategies Inventory, the Beck Depression Inventory, the Symptom Checklist 90-Revised, and the Relationship Questionnaire. There were significant relationships between abuse-severity characteristics and elevated levels of self-criticism and differences in interpersonal functioning. Both self-criticism and avoidant coping predicted psychological symptomatology, but these associations were not specific to abuse victims. Hypothesized relationships between social support and adjustment were not confirmed; however, the findings suggest that attachment style is a particularly sensitive measure of interpersonal functioning within abuse victims.

Piaget (1953) believed object permanence emerges through a series of stages at approximately 18-months. Contemporary researchers have suggested infants achieve object permanence by 3.5-months. A series of studies by Baillargeon (1987) utilized a violation-of-expectation paradigm habituating infants to a paddle moving 180$\sp\circ$. During test trials, a block was positioned in the path of the paddle. During "possible" trials, the paddle moved 120$\sp\circ$, stopped at the block and returned. During the "impossible" trials, the paddle moved 180$\sp\circ$, seemingly through the block. Infants looked longer at the impossible events suggesting an understanding that one object cannot occupy the space of another object contiguously. Looking times could not be explained by detecting perceptual novelty because the impossible event was the more familiar of the test events. Hunter and Ames (1988) have demonstrated that infants look longer at familiar stimuli if they have not thoroughly encoded habituation stimuli. These researchers believed that habituation is a function of time, age, and task difficulty. The current research examines the possibility that infants look longer at impossible events because these events are perceptually familiar. To test whether infants had sufficient opportunity to encode habituation events using the moving paddle paradigm, the number of habituation trials and infants' age were manipulated. Four-month-olds who received 7-180$\sp\circ$ habituation trials looked longer at the 180$\sp\circ$ test event (a significant familiarity preference). Four-month-olds receiving 7-112$\sp\circ$ habituation trials looked longer at the 112$\sp\circ$ test event (a significant familiarity preference). Four-month-olds receiving 12-180$\sp\circ$ habituation events looked significantly longer at the 112$\sp\circ$ test event (a significant novelty preference). A group of 6-month-olds habituated to 7-180$\sp\circ$ trials showed no preterential looking during the test trials. For the four-month-olds, looking times during the test trials were a function of the type of familiarity event and whether there were enough trials to fully encode the habituation events. Looking time was not necessarily a function of an inferred violation of physics. Performance on the moving paddle paradigm might be more easily explained by perceptual mechanisms.

Although it has been hypothesized that children's attention is mediated by their comprehension (Anderson & Lorch, 1983), very little research has examined what toddlers actually understand of what they see on television, mostly due to their limited verbal abilities. Research on the comprehension of other symbolic media (i.e., pictures or scale models) indicates a rapid developmental change between two and three years of age in the realization that a symbol represents something other than itself. Two experiments were designed to non-verbally test whether 2- to 3-year-olds showed a similar developmental progression in understanding the correspondence between television and reality. In Study One, 2-, 2.5-, and 3-year-olds were shown a video of a toy being hidden in a room. Subsequently, they were asked to find the toy. Their performance was compared to that of children who saw the same event through a window. At all ages, children who watched through the window were able to find the toys. Three-year-olds who watched the events on TV were also able to find the toys. Two- and 2.5-year-olds who watched the events on TV were able to find the toy during their first trial but on subsequent trials frequently made an error of going to the location where the toy had previously been hidden. The 2.5-year-olds were able to correct such errors but 2-year-olds had difficulty doing so. In Study Two, 2-year-olds' ability to use televised information was examined with an easier task. They watched on video or through a window as a person placed a toy on a piece of furniture. They were subsequently asked to imitate the toy placement. Performance was again superior after watching presentations through a window than on TV. Two-year-olds performed better with this imitation task than they had with the searching task. Performance was better during the first 2 trials than during the latter 2 trials. The findings from this research indicate that toddlers have some sense of the correspondence between TV and reality. Nevertheless, there are considerable developmental advances in the stability of this understanding between two and three years of age. It was suggested that young toddlers' difficulty with using televised information was due to a weaker representation, requiring them to use alternative strategies. Understanding of the correspondence between television and reality appears to show a developmental progression similar to that seen with other symbol systems, suggesting that there are underlying cognitive changes that are necessary in order for children to be able to understand the representational function.