Individual variation in preferences to maintain vs. change the societal status quo can play out in the political realm by choosing leaders and policies that reinforce or undermine existing inequalities. We sought to understand which individuals are likely to defend or challenge inequality in society by exploring the neuroanatomical substrates of system justification tendencies. In two independent neuroimaging studies, we observed that larger bilateral amygdala volume was positively correlated with the tendency to believe that the existing social order was legitimate and desirable. These results held for members of advantaged and disadvantaged groups (men and women). Furthermore, individuals with larger amygdala volume were less likely to participate in subsequent protest movements. We ruled out alternative explanations in terms of attitudinal extremity and political orientation per se. Exploratory whole brain analyses suggested that system justification effects may extend to structures adjacent to the amygdala, including parts of the insula and orbitofrontal cortex. These findings suggest that the amygdala may provide a neural substrate for maintaining the status quo, and opens avenues for further investigation linking system justification and other neuroanatomical regions.

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.

In two studies we tested for a relationship between consumption of a Western-style diet, characterised by high intakes of saturated fat and added sugar, and individual differences in impulsivity. In Study 1, participants completed both a food frequency measure to assess diet and a measure of trait impulsivity. Greater trait impulsivity was associated with consumption of a Western-style diet in both men and women, independent of body mass index (BMI). Greater intake of sugar-sweetened beverages and take-away food were specifically linked to greater trait impulsivity. In Study 2 lean participants completed a laboratory-based impulsivity battery. Habitually consuming a Western-style diet was associated with greater trait self-report urgency and with more impulsive behaviour on a food delayed discounting task (DDT). Dietary relationships with trait sensation seeking, and performance on the Matching Familiar Figures Test, were moderated by gender. Dietary restraint, disinhibition, and hunger scores from the Three Factor Eating Questionnaire had only a small impact upon the relationship between a Western-style diet and impulsivity. These findings suggest that greater impulsivity is associated with consuming a Western-style diet, with possibly bidirectional causation.

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.

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.

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.

Individual differences in adult human brain structure have been found to reveal a great deal of information about variability in behaviors, cognitive abilities and mental and physical health. Driven by such evidence, what contributes to individual variation in brain structure has gained accelerated attention as a research question. Findings thus far appear to support the notion that an individual’s brain architecture is determined largely by genetic and environmental influences. This review aims to evaluate the empirical literature on whether and how genes and the environment contribute to individual differences in brain structure. It first considers how genetic and environmental effects may separately contribute to brain morphology, by examining evidence from twin, genome-wide association, cross-sectional and longitudinal studies. Next, evidence for the influence of the complex interplay between genetic and environmental factors, characterized as gene-environment interactions and correlations, is reviewed. In evaluating the extant literature, this review will conclude that both genetic and environmental factors play critical roles in contributing to individual variability in brain structure.

Face adaptation techniques have been used extensively to investigate how faces are processed. It has even been suggested that face adaptation is functional in calibrating the visual system to the diet of faces to which an observer is exposed. Yet most adaptation studies to date have used unfamiliar faces: few have used faces with real world familiarity. Familiar faces have more abstractive representations than unfamiliar faces. The experiments in this thesis therefore examined face adaptation for familiar faces.
Chapters 2 and 3 explored the role of explicit recognition of familiar faces in producing face identity after-effects (FIAEs). Chapter 2 used composite faces (the top half of a celebrity's face paired with the bottom half of an unfamiliar face) as adaptors and showed that only recognised composites produced significant adaptation. In Chapter 3 the adaptors were cryptic faces (unfamiliar faces subtly transformed towards a celebrity's face) and faces of celebrity's siblings. Unrecognised cryptic and sibling faces produced FIAEs for their related celebrity, but only when adapting and testing on the same viewpoint. Adaptation only transferred across viewpoint when a face was explicitly recognised. Chapter 4 demonstrated that face adaptation could occur for ecologically valid, personally familiar stimuli, a necessary pre-requisite if adaptation is functional in calibrating face processing mechanisms. A video of a lecturer's face produced FIAEs equivalent to that produced by static images. Chapters 5 and 6 used a different type of after-effect, the face distortion after-effect (FDAE), to explore the stability of our representations for personally familiar faces, and showed that even representations of highly familiar faces can be affected by exposure to distorted faces. The work presented here shows that it is important to take facial familiarity into account when investigating face adaptation effects, as well as increasing our understanding of how familiarity affects the representations of faces.

Our paper illustrates the importance of authenticity to student non-drinkers. Semi-structured interviews focussing on the lived experiences of five non-drinking students were subjected to interpretative phenomenological analysis (IPA). We present four inter-related themes: ‘Retaining authenticity by not drinking’; ‘Tainting the self by drinking alcohol’; ‘Feeling trapped by superimposition and self-exposition’ and ‘Doing what you want with your life’. Self-authenticity informed the decision not to drink, became relevant within conversations about non-drinking, and underscored issues of choice and agency raised by alcohol consumption. Entrenched assumptions about alcohol’s self-realising utility are challenged in our discussion and future research recommendations are suggested.

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.

Current cognitive models stress the importance of negative self-perceptions in maintaining social anxiety, but focus predominantly on content rather than structure. Two studies examine the role of selfstructure (self-organisation, self-complexity, and self-concept clarity) in social anxiety. In study one, self-organisation and self-concept clarity were correlated with social anxiety, and a step-wise multiple regression showed that after controlling for depression and self-esteem, which explained 35% of the variance in social anxiety scores, self-concept clarity uniquely predicted social anxiety and accounted for an additional 7% of the variance in social anxiety scores in an undergraduate sample (N = 95) and the interaction between self-concept clarity and compartmentalisation (an aspect of evaluative self-organisation)at step 3 of the multiple regression accounted for a further 3% of the variance in social anxiety scores. In study two, high (n = 26) socially anxious participants demonstrated less self-concept clarity than low socially anxious participants (n = 26) on both self-report (used in study one) and on computerised measures of self-consistency and confidence in self-related judgments. The high socially anxious group had more compartmentalised self-organisation than the low anxious group, but there were no differences between the two groups on any of the other measures of self-organisation. Self-complexity did not contribute to social anxiety in either study, although this may have been due to the absence of a stressor. Overall, the results suggest that self-structure has a potentially important role in understanding social anxiety and that self-concept clarity and other aspects of self-structure such as compartmentalisation interact with each other and could be potential maintaining factors in social anxiety. Cognitive therapy for social phobia might influence self-structure, and understanding the role of structural variables in maintenance and treatment could eventually help to improve treatment outcome.