Despite continuing interest in the development of children's understanding of the mind, many studies have continued to rely upon one test to measure such a complex understanding; the standard false belief test. This thesis presents two experiments understanding; the standard false belief test. This thesis presents two experiments which move away from this standard test, attempting to unravel early forms of understanding by examining: 1. Whether there are developments in evidence before the 3-4 year 'shift' in standard false belief development; 2. If the child's access to mental state knowledge undergoes a more gradual progression than dominant theorists within the field argue; and 3. What precursor skills (mental state and/or executive function) feed into social understanding.

This work seeks to advance our understanding ofa preschool-age view of the relationship between representations and their referents. Here we have outlined and tested a novel task - the false objects task - designed to mirror its predecessor - the false photographs task (Zaitchik, 1990). In line with previous false photograph work, behavioural measures here have indicated that children perceive representations and their referents to be in accordance with one another, over-endowing referent objects with aspects which are unique to the photograph's own spatiotemporal history. In five initial experiments we have provided a robust demonstration of children's tendency to make errors on this novel task, in contrast to suitable controls and across a range of materials. In the second half of this body of work we sought to investigate the factors contributing to errors on the false objects task, and concluded that these could not be attributed to memory difficulties, cueing or a proclivity to view the situation in accordance with magical casual reasoning. In contrast, error rates reduced when the experimental context encouraged children to view the representation and referent object as separate items. We conclude that these results most strongly support an account of children's difficulty with the dual nature of representations. These findings support and extend our understanding of the repercussions of this difficulty, and indicate that confusion between ''the sign and the thing signified" is evident in children's behaviour as well as in their verbal reports.

Individuals with Down syndrome typically have marked delays in language development relative to their general cognitive development, with particular difficulties in expressive compared to receptive language, and syntax compared to vocabulary. Knowledge is currently limited with regard to which factors in early infancy may predict language outcomes at age 3. The current study assessed a group of infants with Down syndrome and a group of typically-developing infants on a variety of factors that have been shown to be related to language in both typical infants and those with developmental delays. These factors included: Non-Verbal Mental Ability, Speech Segmentation, Initiating Joint Attention, Initiating Behavioural Requests, Responding to Joint Attention, and Parental Responsivity. The primary aim of this longitudinal study was to investigate which of these factors are the strongest predictors of later language in typically-developing infants and infants with Down syndrome. When infants with Down syndrome (mean age 19.5 months) were compared to typically-developing infants of approximately 10 months of age, no differences were found between groups on any of the measures, apart from Receptive Vocabulary and Initiating Behavioural Requests, for which the infants with Down syndrome outperformed the typically developing group. Longitudinal analyses of the relationships between predictor measures and language showed that Speech Segmentation and Initiating Joint Attention were the most important predictors of later language in the typically-developing group, whereas Non-Verbal Mental Ability and Responding to Joint Attention were the most important predictors of later language for the infants with Down syndrome. These results are considered in relation to findings from previous research, and the theoretical implications are discussed, with the findings largely being argued to support a neuroconstructivist view of language acquisition.

Early emotion regulation is an important factor in predicting later socio-emotional development, with difficulties in coping with negative emotions being linked to the development of emotional and behavioural problems. The ability to effectively regulate emotion is a major task for infants and toddlers, and identifying the conditions which promote optimal regulation is an important focus for research. Despite this, little empirical research has addressed its development over time, particularly in the first three years. Moreover, research has emphasised the importance of parenting in children's development of emotion regulation, yet limited studies have looked at the direct effect of parental support on infants' developing emotion regulation. The current thesis seeks to extend existing research by examining the developmental trajectory of emotion regulation over infancy and toddlerhood, and by investigating the relative contribution of parental involvement over time. Participants were 136 mother-child dyads. The main analyses focused on a frustrating, toy separation task, which was administered when children were 15-, 26-, and 37-months, during which the level of support mothers could provide was manipulated. Child and parent behaviour was coded based on their responses during the task. Analyses found that emotion regulation improved with age, beginning to stabilise between 2 and 3 years of age. Younger children showed more distress and less regulation with increased maternal involvement, while they demonstrated the reverse effect as they got older. Concurrently, sensitive, responsive parenting was associated with less distress and more effective emotion regulation, while intrusive parenting behaviours were associated with more distress and less effective regulation. There was also evidence to suggest that some of these findings may extend longitudinally. These findings emphasise the importance of external factors influencing the development of emotion regulation, particularly demonstrating the importance of active parental involvement and sensitivity in facilitating optimal regulation. Results are discussed with reference to child temperament, attachment, and gender.

This study describes a critical exploration of theory into practice. Two principles of Vygotskian cultural historical theory: mixed age play and enhanced home-school links, already integrated into practice in Zolotoi Kluchick (Golden Key) programme schools in Russia, were adapted and implemented in an early years setting (3-6 years) in Northern Ireland. These principles were implemented, evaluated and modified, in a cyclic process, involving the school community throughout. Over one school year, six teachers, 15 classroom assistants, 106 children, five sets of parents, and the researcher, formed a pedagogical collective to explore both the process of implementation, and resultant impact of the Intergrated Play Programme (IPP). The study explores critically the translation of Vygotskian theory into practice. A constructivist methodology was employed, which viewed collaboration within the school community as vital to its success. Vygotskian theory was foundational in the developmental methodology that saw new research methods emerge throughout the research. Findings and conclusions drawn from this study were drawn primarily from participant perspectives. Vygotskian concepts of the zone of proximal development (ZPD), social situation of development (SSD), internalisation and cultural mediation guided the analysis, evaluation, and reflection. Findings revealed that the translation process was not straightforward, and required modifications to the original principles. The concept of 'family' appeared to connect home and school emerged as the major factor in modifying the implementation process. A 'family pedagogy' was developed, in which mixed-age play groups were known as 'school families'. Children's discussion of their 'school family' at home generated curiosity and interest from parents and carers, and provided a dialogical tool and cultural tool to bridge children's home and school learning. The study highlights the value of using play as the basis for this family pedagogy and, in line with Vygotskian theory, presented play as the predominant developmental activity for young children

This study, undertaken in Nicosia, Cyprus, explored the impact of developmentally appropriate practices (DAP) by studying how the attitudes and practices of Greek/Cypriot parents (n = 142) and teachers (n= 16) regarding the developmental importance of academics and play vary, and in particular, how classroom practices are related to the social, emotional and cognitive development of Greek/Cypriot children (n = 142) between 4.10 and 7.0 years of age. Results indicated that observed and reported classroom practices were related systematically to parental attitudes and practices, thereby providing evidence of selection that needed to be statistically controlled. Children exposed to fewer art activities in the classroom were rated as being more playful by their teachers, and younger (i.e., preschool) children in more developmentally inappropriate classrooms scored higher on teacher-rated social skills. Grade-I children in more developmentally appropriate classrooms manifested greater anxiety in the testing situation. Children who were in classrooms in which teaching practices and values regarding play proved inconsistent with the those of their families scored higher on teacher-rated behaviour problems; however, children in classrooms in which family- classroom consistency was the norm scored higher on parent-rated behavioural problems. Because some of the results were inconsistent with previously-reported findings, and hence contradict the claims that inappropriate classroom practices are harmful to young children, the question arises as to why this proved to be the case in Cyprus. Implications for future research are therefore discussed.

Background: The prevalence rates of aggressive and antisocial behaviour among children and adolescents are a cause for concern among parents, teachers and policy makers. The aetiology of these dimensions of child psychopathology remains high on the research agenda. Attention has been directed at specific family relations, including inter-parental and parent-child relationships, and school-based factors, such as student-teacher relationships and school transitions, as aspects of children's social environment that may contribute to externalising problems. This thesis explores the role of home-school interplay by examining the pathways through which pre- and post-transition inter-parental conflict is associated with children and adolescents' externalising problems in secondary school. Method The thesis employs a mixed methods design. Multivariate analysis using both cross-sectional and prospective, longitudinal research designs are used to assess relationships between inter-parental conflict and children's externalising problems during the transition from primary to secondary school. This is supplemented by a thematic analysis of qualitative responses identifying the school-based factors that children, their parents and teachers have identified as helpful and unhelpful to foster adaptation to school transition. Results Findings emphasise the importance of family relations for children's school- based adjustment. Inter-parental conflict preceding and co-occurring with the school transition consistently predicted externalising problems in secondary school via children's responsibility attributions for the conflict. The results also underscore the value of considering the interface between home and school for understanding variation in children's psychological adjustment by showing that inter-parental conflict increases children's transition-related anxiety, which predicts poor adjustment to secondary school. Supportive teacher behaviour appears to be a significant factor that helps children prepare for the transition. It appears to be particularly important for children experiencing heightened levels of discord and hostility within the home, who may be among those at greater risk of manifesting externalising problems. Conclusions It is important to consider aspects of the home and school environment to understand variation in children's externalising problems in school during periods of transition. Results are discussed and recommendations made for policy and practice aimed at reducing aggression and antisocial behaviour during this critical period of normative life stress.

This thesis's aim was to examine the effect of vocal intonation on mental state understanding. This thesis has found that vocal intonation provides important cues for communicating the intentions of others' to infants. The results indicate that infants rely on intonation when making attributions about other people's goal-directed behaviour. These results were first found using an imitation paradigm and extended and confirmed with a looking time paradigm. The first two experimental chapters of this thesis have shown that the tone of voice is a salient cue to mental states. Infants did not only distinguish between intentional and accidental words such as "Whoops" and "There" but they also made the distinction between intentional and accidental mental states from the intonation alone. A looking time measure has also shown promising results for the same distinction between intentional and accidental mental states. The looking time study has confirmed and extended the findings that we saw through imitation. Infants seemed able to distinguish between an intentional and an accidental intonation and looked longer during scenes where the accidental intonation was paired with the end-result. These findings are the first to report results on the intonation of accidental and intentional mental states. The results of this thesis contribute to the literature concerning intention understanding and they extend our knowledge about intonation and the significant role it plays in infancy.

This thesis draws on Jacques Derrida's idea of 'differance' (difference as both distinction and deferral) to argue that, within post-Darwinian humanist culture, the category of 'the human' can only be defined by differentiating it from 'the animal'. Following Derrida, this project seeks to 'determine the number, form, sense, or structure' of the 'plural and repeatedly folded frontier' between these two categories. Chapter 1, 'Becoming Human', examines the chronological boundaries between the human and extinct hominids such as <italic> Homo erectus</italic> and Neanderthals. It reads contemporary scientific accounts of 'how we became human' to demonstrate that they preserve the conceptual framework of earlier creation myths. However, despite their humanism, these accounts inevitably unsettle the boundaries between human and animal by revealing the play of traces across them. Chapter 2, 'Acting Human', reads Descartes' <italic> Discourse on the Method</italic> with Judith Butler's theory of gender performance to argue that the human can only be identified by its behaviour. Those who do not behave 'correctly', such as people with autism, threaten humanism and are consequently punished. Conversely, when animals are seen to 'act human' (for example, the chimpanzee artist Congo) this is dismissed as anthropomorphism. However, these possibilities demonstrate that human behaviour is not tied to an internal essence. Chapter 3, 'Talking Human', deconstructs the opposition between human language and animal communication which underpins contemporary humanist discourse. The human voice is identified with presence, truth and subjectivity, while animals are mute, inarticulate objects. However, the human subject is never fully in control of its communication, as demonstrated by blushing and involuntary nonverbal 'leakage'. I conclude that 'language' and 'the human' are constituted only by referring to each other. This thesis critiques the mythology of humanism in order to challenge the unethical acts that are committed in the name of the human.

This thesis investigates whether children's understanding of both mental and non-mental representations can be accounted for by the same underlying competence in representational understanding. This research question stems from a long-standing dispute between domain-specificity and domain-generality in understanding mental representations. In Chapter 1,1 highlight the importance of using false representations to assess representational understanding, and discuss a fundamental problem inherent in previously devised false non-mental representation tasks in comparison to false mental representation tasks. I also outline the confounding of other cognitive skills such as language and executive function during the assessment of representational understanding. This motivates the subsequent empirical work for this thesis which includes (1) the development of novel measures for assessing children's understanding of non-mental representations and (2) the investigation of the equivalence between children's understanding of mental and non-mental representations. Evidence for this equivalence was shown by a transfer of training between a new false non-mental representation task and an existing false mental representation task presented in Chapter 2. With the use of another novel false non- mental representation task which minimises and eliminates the confounding factors of language and cognitive inhibition, the two experiments in Chapter 3 further indicated that the equivalence between false non-mental and false mental representation tasks could not be explained by these confounding factors. Chapter 4 extended the research from typical to atypical development, namely Autism Spectrum Disorder (ASD) as individuals with ASD are known to be specifically impaired in processing social and mental information. Intriguingly, the findings in Chapter 3 were shown to be generalised to children with ASD. Finally, the consistent findings of the five experiments reported in this thesis are discussed in relation to the theoretical accounts and neurological basis of typical and atypical cognitive development.