Computer models are used to simulate pedestrian behaviour for safety at mass events. Previous research has indicated differences between physical crowds of co-present individuals, and psychological crowds who mobilise collective behaviour through a shared social identity. This thesis aimed to examine the assumptions models use about crowds, conduct two studies of crowd movement to ascertain the behavioural signatures of psychological crowds, and implement these into a theoretically-driven model of crowd behaviour. A systematic review of crowd modelling literature is presented which explores the assumptions about crowd behaviour being used in current models. This review demonstrates that models portray the crowd as either an identical mass with no inter-personal connections, unique individuals with no connections to others, or as small groups within a crowd. Thus, no models have incorporated the role of self-categorisation theory needed to simulate collective behaviour. The empirical research in this thesis aimed to determine the behavioural effects of self-categorisation on pedestrian movement. Findings from a first study illustrate that, in comparison to a physical crowd, perception of shared social identities in the psychological crowd motivated participants to maintain close proximity with ingroup members through regulation of their speed and distance walked. A second study showed that collective self-organisation seemed to be increased by the presence of an outgroup, causing ingroup members to tighten formation to avoid splitting up. Finally, a computer model is presented which implements the quantified behavioural effects of self-categorisation found in the behavioural studies. A self-categorisation parameter is introduced to simulate ingroup members self-organising to remain together. This is compared to a physical crowd simulation with group identities absent. The results demonstrate that the self-categorisation parameter provides more accurate simulation of psychological crowd behaviour. Thus, it is argued that models should implement self-categorisation into simulations of psychological crowds to increase safety at mass events.

The ability to accurately interpret facial emotion is crucial to social being and our capacity to correctly interpret threat-related expressions has obvious adaptive value. Healthy individuals appear to process facial emotions rapidly, accurately and effortlessly, while individuals with schizophrenia often present with marked impairment in emotion processing. The hypothesis of continuity between schizophrenia and normal behaviour suggests that the signs and symptoms of the disorder also occur to varying, lesser degrees in the general population. This thesis presents a series of studies that explore the limits of facial emotion processing in healthy individuals, and its relationship with schizotypal personality traits. The first paper describes a set of three studies that use eye tracking techniques to explore the limits of rapid emotion processing. It is shown that we can quickly orient attention towards emotional faces even when the faces are task-irrelevant, presented for very brief intervals, and located well into peripheral vision. The remaining studies explore whether high schizotypes have similarities to individuals with schizophrenia in the way that they process facial emotion. High schizotypes were significantly less accurate at discriminating facial emotions and significantly more likely to misperceive neutral faces as angry, offering support for continuum models of visual hallucinatory experiences. A further study revealed that high relative to low schizoptypes feel as though they are exposed to angry faces for longer. It is argued that this experience itself may serve to maintain hypervigilance to social threat. Finally, laterality biases during face perception were explored. Contrary to the predictions of continuum models of schizophrenia, high schizotypes had an increased left side / right hemisphere bias for face processing. In summary, the thesis offers partial support for the hypothesis of continuity between the impairments in emotion discrimination observed in individuals with schizophrenia, and normal, healthy variation in facial emotion processing.

Self-affirmation has been successfully applied as a technique to promote open processing of health-risk information. However, much research in this area has explored the uniform effectiveness of self-affirmation interventions. The current thesis adds to existing literature by exploring whether different aspects of self-regard moderate self-affirmation effects. Study 1 (N = 328) investigated whether global self-esteem moderated the effectiveness of self-affirmation at promoting openness to a message highlighting the risks of insufficient exercise. Global self-esteem was found to be a significant moderator. Self -affirmed individuals with low global self-esteem reported more positive attitudes and intentions towards increasing their exercise behaviour, together with less message derogation; there was no effect of self-affirmation for those high in global self-esteem. Study 2 (N = 166) extended this research by exploring the moderating impact of a variety of self-regard aspects on self-affirmation effects. Contingent self-esteem emerged as a significant moderator. Thus self-affirmed individuals with low contingent self-esteem reported more positive attitudes and perceptions of control towards increasing their exercise behaviour; there was no evidence that self-affirmation promoted openness for those high in contingent self-esteem. Study 3 (N = 139) explored whether experimentally induced contingent self-esteem moderated the effectiveness of a self-affirmation manipulation at promoting open processing of a message detailing the risks of insufficient exercise. There was no evidence of this for any of the outcome variables. Lastly, study 4 (N = 125) investigated whether the moderating impact of global and/or contingent self-esteem on self-affirmation effects would extend to a message detailing the risks of alcohol consumption. Both self-esteem aspects moderated the impact of the self-affirmation manipulation on perceptions of behavioural control regarding reducing the amount of alcohol consumed. Moreover, self-affirmation was associated with lower levels of alcohol consumption at follow-up for those with low global self-esteem, and with higher alcohol consumption at follow-up for those with high global self-esteem.

Exercising to improve one's appearance has been consistently associated with negative body image (e.g., Tiggemann & Williamson, 2000). However, little is known about either the processes underlying this association, or the causal direction of the effects. This thesis draws upon both self-determination theory (SDT; Deci & Ryan, 2000) and objectification theory (Fredrickson & Roberts, 1997) in order to investigate the role of regulations for exercise and self-objectification in the link between appearance goals and body image. The thesis examines both individual variations in these constructs, and their influences on body image among young women, utilising cross-sectional, longitudinal and experimental methodologies with both student samples and a community sample of gym-users (Chapter 2 and 3). It also considers factors in the exercise environment that can influence regulations of behaviour and feelings of self-objectification, using the physical education classes of adolescent girls as an exemplar (Chapter 4 and 5), drawing upon recent work on objectifying environments (Moffitt & Syzmanski, 2011) and the existing self-determination theory literature on motivation in physical education. The four empirical papers highlight in particular the importance of introjected, or guilt-based, regulation in the link between appearance goals and negative body image, and illuminate the associations with self-objectification. Furthermore, they highlight the negative impact that an objectifying and non-autonomy supportive environment can have on girls' engagement in and enjoyment of physical education, and on their body image. The theoretical and practical implications of these findings are discussed, in relation to an integration of self-determination and objectification theories as well as the potential for autonomy-supportive, non-objectifying exercise interventions that de-emphasise guilt and emphasise the intrinsic value and joy of physical activity.

Section A provides a literature review of transgender people and their friendships. The first part of the literature review explores the historical context of transgenderism and its relation to medical and psychiatric diagnosis. The following part concentrates on biopsychsocial issues of transgender identity formation highlighting the need for support in light of interpersonal losses and societal discrimination. The final part reviews the friendship literature more generally, then specifically in relation to transgender persons. The review concludes by identifying an absence of friendship research with transgender individuals and suggesting directions for future research. Section B describes a study carried out with seven trans men, which investigates discourses they use to construct friendships and negotiate intimacy within friendships. While research focusing on friendships of sexual minority individuals has increased over the last two decades, studies of transgender persons’ friendships have been largely absent. Given that trans individuals are vulnerable to a range of psychological stressors in the context of societal lack of understanding and discrimination, friendships may be particularly important. This study explored the gap in the friendship literature and drew on creative methodologies (drawing of systems maps) that offered empowering strategies to facilitate trans men’s stories of friendships. Foucauldian Discourse Analysis was applied to analyse discourses of friendship and gender identity. Dominant discourses identified included ‘friends as family’, ‘romantic love’, ‘equality and reciprocity’, ‘change in lesbian friendships’ and ‘disowning male privilege’. The results indicate that trans men elevate the status of friends to those of other culturally dominant relationships (e.g. biological family or sexual partner). Furthermore, their friendships, in particular lesbian friendships, can become complex platforms from which to contest privilege and power associated with their (trans) masculinities. Implications for further research and clinical practice are discussed. Section C provides a critical appraisal of the study and offers the researcher’s reflections on research skills developed, what she would do differently if she could do the project again, how the research may impact her clinically and what further research she would like to carry out.

Psychiatric diagnosis is used to categorise and treat mental health problems in the UK yet is widely criticised for struggling to convincingly categorise the experience of distress and that it is socially constructed from the culmination of historical and cultural interactions. Service-user accounts are varied and there is a paucity of qualitative research that considers the positive and negative effects of labelling. To understand identity construction in the context of a psychiatric diagnosis, the present study recruited 16 participants from a service-user research group and five focus groups were conducted. Transcripts were studied using Foucauldian Discourse Analysis. Two major identities were detected ‘illness identity’ and ‘recovery identity’. Participants drew on multiple and competing discourses and which placed them in the position of patient and/or survivor. Medical discourses were dominant throughout the focus groups and were used in a way to convey the fluidity of the identity and how they related to their diagnosis. The study’s limitations are discussed, together with implications for clinical practice and future research.

Little research has looked in detail at the subjective experience of adolescents who have been admitted to psychiatric hospital and the potential impact of this on their developing identity. This study aimed to construct a theory of the perceived impact of hospitalisation on the identity of young people admitted to a psychiatric ward, the ways young people might manage threats to their identity and any perceived impact of diagnosis. Nine young people aged 15-17 were interviewed in depth about their experience of admission and any perceived impact on their identity. Young people were current in-patients or ex-patients attending follow-up treatment in the community. Grounded theory methodology was employed in this study. A preliminary model is proposed showing the process from admission to post-discharge with hypothesised impacts on personal and social identity at each stage. Positive outcomes were associated with an improved sense of self and self-efficacy. In contrast, the development of an “illness” explanation for one’s difficulties while in hospital may be a risk for a more negative self-concept and a less favourable future outlook. The study concluded that longitudinal research is required to ascertain long-term outcomes of the proposed model. Emphasizing psychological formulation may ameliorate the perception of individual ‘deficit’ that appeared to be associated with diagnosis.

Section A critically reviews relevant theoretical literature and empirical studies exploring the particular impact of chronic illness on identity formation in adolescents. Theoretical conceptualisations of the adolescent period and of the process of identity formation are explored. Following this, empirical literature regarding the impact of chronic illness on the developmental tasks of adolescence and in particular identify formation will be critically examined. A number of clinical implications are discussed to enable clinicians to effectively support young people and future research directions are outlined. Section B reports a narrative analysis of young people's experiences of forming an identity with a diagnosis of an adolescent-onset chronic illness (CI). Identity formation is argued to be one of the key developmental tasks of adolescence. Despite implications for adolescent development, research into CI onset during this period has been notably sparse. This study aimed to explore how diagnosis impacts on the developmental tasks of adolescence, what role adolescent-onset CI plays in identity formation, and how adolescents incorporate the diagnosis into their identity. Individual semi-structured interviews were carried out with 8 young people aged 14-19 who lived with a diagnosis of a CI diagnosed between the ages of 12-16 years. Two illness types were studied; crohn’s disease and juvenile idiopathic arthritis. Interviews were audio-recorded, transcribed and analysed using narrative analysis. Participant narratives contained five core narrative themes: Walking a different path, tolerating contradiction, a changed interface with others, locating power and a fluid relationship. Narratives were considered to have been influenced by factors such as the interview context and dominant social narratives concerning health and illness. Adolescent-onset CI was found to have a significant, though not exclusively negative, impact on developmental tasks. The findings are discussed in relation to existing literature and potential clinical implications. Section C critically appraises the narrative study. A discussion begins with reflections on the research skills developed and insights into the research process. Areas of further learning are identified. Implications of clinical practice are explored and the section concludes with considerations for further research in this area.

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The amount of food thrown away by UK households is substantial and, to a large extent, avoidable. Despite the obvious imperative for research to identify key factors that motivate, enable or prevent household food waste reduction, little research to date has directly addressed this objective. The research presented in this thesis had two clear aims: (1) to investigate antecedents of household food waste reduction and barriers to change, and (2) to explore whether self-affirmation techniques can increase motivation to reduce household food waste. Four empirical studies were conducted. The first study qualitatively explored thoughts, feelings and experiences of 15 UK household food purchasers. Analysis revealed seven core categories representing both motivations and barriers to household food waste reduction. The second study (N = 279) applied an extended theory of planned behaviour (TPB) model to predict household food waste reduction intention and behaviour. Results revealed that the extended TPB variables predicted 64.55% of intention to reduce household food waste and 5.03% of the variance in household food waste behaviour. Studies 3 and 4 explored whether self-affirmation techniques would promote openness to information detailing the negative consequences of household food waste. Study 3 (N = 224) found that self-affirmed participants reported more positive cognitions towards household food waste reduction on a number of outcomes compared to their nonaffirmed counterparts. However, there was no impact of the self-affirmation manipulation on behaviour at follow-up. Study 4 (N = 362) failed to replicate the impact of selfaffirmation on cognitions. However, self-affirmed participants reported that they threw away less household food waste at follow-up. Further research in the context of selfaffirmation on food waste reduction behaviour is required.