Mobile communication devices are now truly ubiquitous; they are present everywhere in the modern world. They are also the first human artefacts capable of automatically detecting the subtle ways in which people reveal the nature of the relationships between them. This information is contained within the communications metadata available on these devices. By analysing these communications metadata certain tie signs become discernible and it becomes possible to estimate the current state of the social relationships of the user of the device. However, although this information is available on mobile communication devices few established techniques for gathering, and interpreting it have been defined. This thesis presents empirical investigations into detecting and categorising social relationships using mobile devices. It introduces mechanisms to detect the social ties between the users of mobile devices, based on the interactions between them, and explores techniques to accurately categorise these ties. The ability to detect social ties allows the construction of a social graph with out any prior knowledge of the social relationships between the users of mobile devices. The results of the investigations reported in this thesis show that, although large amounts of data are lost while gathering social social data using mobile devices, estimated ties are confirmed to be correct in the majority of cases.

Social categorization based on group membership has a significant and broad influence on behaviour (Turner, Hogg, Oakes, Reicher, & Wetherell, 1987). People perceived as being of the same group, ‘in-group' members, are accorded all kinds of special treatment, such as the tendency to reward them over out-group members (Tajfel, Billig, Bundy, & Flament, 1971). At the other extreme is denigration based solely on a person's status as ‘out-group' member, sometimes even to the point of perceiving that person as less human than fellow in-group members, a phenomenon termed dehumanisation (Leyens et al., 2001). Historic examples of dehumanisation are abundant, such as the extermination of Jews in Nazi Germany. What is less well understood, however, are the cognitive processes involved in these inter-group phenomena. How can a normal human being, with fully functioning cognitive faculties, come to not only view another person as sub-human but also to act on such irrational beliefs? One cognitive ability that, according to theory, plays a pivotal role in every human social interaction is the ability to attribute mental states to others, which enables humans to construct a theory of the minds they interact with. Having a ‘theory of mind' allows an individual to interpret and predict behaviour in terms of underlying mental states (Premack & Woodruff, 1978). It is widely acknowledged that theory of mind is of fundamental importance to human social interactions (Baron-Cohen, Tager-Flusberg, & Cohen, 2000). For example, the ability to understand others' intentions and goals allows humans to participate in collaborative action with shared ends, a hallmark capacity required for human social structures such as governments and economic systems (Tomasello, Carpenter, Call, Behne, & Moll, 2005). Given the importance of theory of mind to daily human life, a critical question thus is when and how theory of mind is actually used, especially in inter-group contexts such as those previously mentioned. While the developing, abnormal, and non-human theory of mind have been thoroughly investigated, much less is known about how normal adults deploy their theory of mind in actual social situations, including in situations of inter-group conflict. The present thesis has the primary aim of understanding how group membership affects the quotidian functioning of theory of mind and the social cognitive abilities that form its foundation, representation of intentionality and more basic processes of social learning. To this end, I will examine the effects of group membership on normal adults' theory of mind usage (study 1). I will then go on to look at the deeper effects of group membership on social cognition, particularly its effect on some of the building blocks of theory of mind, representation of intentionality and basic social learning. To this end, I will first look at how intentionality is represented as a function of a person's group membership with and without social competition (studies 2 & 3), and on how perceptions of group membership and social power impact basic social learning processes (studies 4 & 5). This process will elucidate the degree to which social cognition processes, from theory of mind down to its basic cognitive roots, are affected by perceptions of group membership. A secondary goal is to generate more informed hypotheses about the nature of the cognitive mechanisms underlying group- based social phenomena, such as dehumanisation.

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A behaviour change towards sustainable food purchasing behaviour is crucially necessary for the survival of the planet. This thesis applied a mixed method approach, combining results from a cross-sectional online survey (N=474), a lab experiment (N=134) and an agent-based model (ABM) to explore how a change towards sustainable food purchasing may be achieved in society. The methodological approach of this thesis is quantitative confirmatory and exploratory. The online survey, based on main environmental psychology theories (Theory of Planned Behaviour, Norm Activation Model and habit theories) and social network theory, explored which factors significantly influence sustainable food purchasing behaviour. Findings show that social network factors influence sustainable food purchasing behaviour via psychological factors; habit, perceived behavioural control, descriptive and personal norms. Additionally, segmentation of different sustainable behaviour groups (high, medium and low) let to the development of segment specific intervention strategies. The lab experiment, measuring actual sustainable food consumption behaviour, validated and extend these findings by showing that social network members significantly influence sustainable food consumption behaviour compared to strangers. I further applied the empirical findings and theoretical knowledge to build an ABM to understand (1) the spread of sustainable food purchasing behaviour, and, (2) how three social network factors (i.e. network size, percentage of sustainable shoppers and percentage of food discussion partners in the social network) influence this spread of sustainable consumer behaviour via psychological factors shown to be relevant to influence sustainable purchasing behaviour (i.e. intention, habit, personal and descriptive norm). Findings provide evidence that there is (1) a threshold effect during the spread of sustainable food purchasing behaviour in social networks as the spread of sustainable food shopping behaviour is fastest at the beginning phase of the experiments, slowing down towards the middle and end phase. The speed of the spread of behaviour is significantly influenced by the size of the social network and the percentage of initial sustainable shoppers in the personal network (2). This research provides a first glimpse of what behaviour change towards sustainable food shopping may look like with the influence of social networks. Intervention and policy recommendations are discussed.

Overview The current thesis reports on the design and development of a social support measure which explores the perceived functional social support needs of family members who have a relative with a substance related problem. A mixed methodological approach was adopted to operationalise the concept of social support specific to concerned and affected family members, thus completing the nomological set of instruments required to quantitatively assess the Stress-Strain-Coping-Support (SSCS) theoretical model of addiction and the family. Methods The 75-item self-completion Alcohol, Drugs and the Family Social Support Scale (ADF SSS) was piloted with 10 family members, and the resultant 58-item measure was then subjected to extensive psychometric testing with 132 family members, and qualitative feedback was gleaned from 110 family members. This resulted in the production of a refined 25-item questionnaire. Findings Preliminary findings on the refined 25-item questionnaire indicate satisfactory levels of reliability (internal and test-retest) and validity (content and construct) for the overall measure and each of the three constituent sub-scales: frequency of positively perceived general (α=0.913) and ADF related (α=0.727) functional support, and frequency of negatively perceived ADF specific (α=0.851) functional support. Qualitative information from family members revealed that the questionnaire was experientially applicable to their situation in dealing with the excessive substance use of a close relation. Discussion The significance of producing a concise, psychometrically sound social support measure for concerned and affected family members is discussed in the context of implications for research, theory, policy and practice in the field.

In this thesis we contribute to the understanding of online social networks, temporal networks, and non-equilibrium dynamics. As the title of this work suggests, this thesis is split into two parts, \emph{monitoring} and \emph{modelling} social networks. In the first half we look at current methods for understanding the behaviour and influence of individual users within a social network, and assess their robustness and effectiveness. In particular, we look at the role that the temporal dimension plays on these methods and the various representations that temporal networks can take. We introduce a new temporal network representation which describes a temporal network in terms of node behaviour which we use to characterise individuals and collectives. The new representation is illustrated with examples from the online social network Twitter. We model two particular aspects of social networks in the second half of this thesis. The first model, a generalisation of the popular Voter model, considers the dynamics of two opposite opinions in a heterogeneous society which differ by the resolve of their opinion. The second model investigates how the presence of `anti-bandwagon' agents can prevent the spread of ideas and innovations on a social network, particularly on networks with restrictive topologies. This contribution offers new ways to analyse temporal networks and online social media, and also provokes new and interesting questions for future research in the field.

Online social networks pose particular challenges to designing effective algorithms and protocols. Apart from their distributed nature, their behaviour depends on user behaviour and is difficult to test at a realistic scale. Stochastic graph transformation systems can model the operation of such networks but due to the inherent complexity they are hard to analyse. Techniques such as model checking and simulation, which can be used to verify a range of quantitative properties, do not scale well to systems with large graphs and state spaces. Aiming for an efficient alternative, we propose to derive a system of differential equations approximating the average evolution of the network. Variables in these equations represent numbers of occurrences of patterns selected to observe structural features. To keep the number of patterns small, rather than aiming for a fully accurate model we approximate complex patterns by the composition of simpler ones. We describe the approximation and its implementation based on critical pair analysis, illustrate and validate the process by examples of a social network protocol for P2P content policing and a voter model. We will also point out limitations in our approach to approximation and the use of differential equations more generally and discuss how they can be overcome.

Traditionally, research in the decision analysis community has focused on psychological impediments to rational decision making, leading to the development of tools and techniques for decision analysts to help their 'deficient' clients. Although this traditional research framework has led to sophisticated tools and many successful applications, it has also contributed to a fragmented decision analysis community residing in three distinct 'schools' and a current focus on trying to understand the pitfalls of application. This thesis describes a new research framework which arose out of exploring six case studies covering a wide degree of success in applying decision analysis The new framework views the application of decision analysis as a joint intervention into organisational. decision making processes by clients and consultants, and success is achieved when the joint intervention is appropriately designed and implemented to meet both social and technical needs within the organisation. This research concludes that successful institutionalisation of decision analysis requires (1) an early intention to do so, (2) a defined product/process to be institutionalised, (3) a stable home for the product/process, and (4) senior management supporting decision analysis as a value adding process for the organisation and for internal practitioners. It also reveals two further sets of conditions whereby highly successful interventions occur, firstly with a champion and consultant operating as leader-follower on a long term high level organisational change process, and secondly by providing a high level umbrella support for managers to choose to use decision analysis if they wish as part of a process of delegating authority. Finally, this research explores the different schools of decision analysis and concludes that primarily the schools have formed to meet different social and technical needs within an organisation. With a view to increasing understanding for both decision analysts and clients, I offer a new research agenda to further explore the organisational engagement of decision analysis.

According to Adams' (1965) equity theory. individuals determine how fairly they are being treated in relationships by comparing their ratio of inputs and rewards with those of a comparison other. A small number of studies on staff working in services for people with learning disabilities (LD) have utilised this theory, A review of these studies found a number of theoretical and methodological issues that require investigation. The aim of the current study was to address these issues. Specifically, its main aims were to (I) find out what inputs and rewards are relevant to LD service staff and who they compare themselves to (2) develop and evaluate a detailed measure of staff equity perceptions that is suitable for LD service staff - The Equity Perception Scale - Learning Disability Service (EPS-LDS) - and (3) expand on previous research by investigating whether staff equity perceptions are associated with a number of variables that have not previously been investigated within the context of LD services (i.e. performance, job satisfaction and organisational commitment). Data was collected using a combination of qualitative and quantitative methods (i.e. semi-structured interviews (n=; 15), focus groups (n = 7) and postal questionnaires (n = 143)) and data analysis procedures (e.g. template analysis and non-parametric statistical tests). A wide range of inputs, outcomes and comparison others were identified. Overall, the EPS-LDS was found to possess acceptable internal consistency reliability, construct validity and criterion validity. The overall test-retest reliability of the measure, however, was found to be unsatisfactory. Staff equity perceptions were found to be associated with performance. job satisfaction and organisational commitment. Possible explanations for some of the findings are forwarded. The results are discussed in terms of their implications for research and practice. Directions for future research are proposed.