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The ability to navigate a spatial environment strongly depends on how well individuals learn, represent and make use of their knowledge about the environment. In the past, research investigated these aspects separately and often in a virtual environment. The current work studied these three aspects of navigation in a real-real world setting to understand how humans navigate naturally in a complex, urban environment like London, UK. Of particular interest was to determine if there was evidence of hierarchical representations during route planning as found in previous behavioural, neuroscientific or computational studies. Most past studies have explored knowledge for simplistic environments or fragmented knowledge of real-world environments. By contrast, licensed London taxi drivers acquire a unique, almost perfect mental representation of the street network, the location of places and the traffic rules that apply to it. Here, the rare knowledge of these navigation experts was explored in three studies with novel approaches. First, to gain an understanding of the training process of unqualified taxi drivers, information from an interview with a teacher, training lessons and study material was collected, summarised and reported. A range of learning strategies was identified that was linked to theoretical, map-based learning and practical, in-situ experiences of London and pointed towards a segmented planning of routes through subgoal selection. Second, a potential mental segregation of London was studied with qualified taxi drivers through boundary drawings of specific London districts with a paper map to understand a potential hierarchical representation. Higher agreement was found for geographical structures and topically distinct districts surrounded by a linear, almost rectangular street network, whereas agreement was lowest for irregularly shaped districts with similarities to neighbouring areas. Finally, taxi drivers were asked to plan and then verbally recall each street they would take along routes between selected origin destination pairs. Audio recordings of these routes made it possible to relate the response times between individual streets to specific street network properties. The analysis using a linear mixed model indicated slower responses at upcoming turns and entering main roads, whereas boundary streets were recalled faster, as were finial streets when compared to initial street. No effects of Euclidean distance or detours were found. Observations from the training process indicate that a potential segregation of the environment, which might impact on later route planning, might be formed already through specific learning strategies. Faster response times for boundary streets support models in which planning is hierarchical. These findings extend past work on route planning in lab-based networks to real-world city street networks and highlight avenues for future research to explore and make use of real-world data.

This thesis brings together historical and empirical research on colour-shape correspondences. Historical accounts usually start with Wassily Kandinsky’s universal visual language of art and design, which explored colours and forms in depth as fundamental building blocks. Whilst colour-shape correspondences provide an example of an intramodal sensory correspondence, modern empirical work in this area has typically been grounded in the field of crossmodal correspondences research. All empirical work conducted on colour-shape correspondences is examined through a systematic review of 28 articles (k = 50, N = 4599), finding, on average, colour and shape to be associated to a small to moderate degree in terms of effect size. However, many inconsistencies in research to date are also found. Over the course of nine experiments, the high amount of variance in colour-shape matches and their task and stimuli-dependent nature is demonstrated. Particular areas that are explored are whether certain shape characteristics can be found that predict chosen colour characteristics, the role of individual differences, and the relationship of colour-shape correspondences with aesthetics. Key conceptual, statistical, and practical issues are highlighted throughout the thesis. Finally, a theoretical groundwork for colour-shape correspondences is posited based on a dynamic representational geometry associative model for intramodal and crossmodal correspondences.

Social contexts often change how people engage with and evaluate available rewards, leading to behaviours that defy simple rules of reward maximization. The current thesis aims to characterize some of the principles that underlie reactions to rewards obtained in a social context and formalize them in computational models. In study 1, I explore how social reward distributions change the hedonic and motivational value of rewards. The study shows that people are often demotivated and distressed by the unfairness of the distribution, and are less willing to work for their offered rewards even if they are the ones benefiting from the unfair situation. I introduce a model that characterizes the responses to reward distributions as a linear combination of statistical dispersion and rank ordering of the rewards and show that its predictions fit more closely to observed behaviour than many other alternative models suggested in behavioural economics and psychology. In study 2, I test how people form subjective judgments about reward distributions. The study demonstrates that subjective judgments are biased by personal position in the distribution, and violate several normative axioms used in economics. In study 3, I demonstrate the effect of the international distribution of rewards on life-evaluations: the study shows that life evaluations are not only sensitive to comparisons with citizens in one’s own country, but also to comparisons with people in other countries. The model characterizing the response to reward distributions as a linear combination of statistical dispersion and rank ordering again is shown to fit well-being data better than any other alternative. Study 4 focuses on the influence of the distribution of beliefs about oneself on preferences for feedback. It shows that people sometimes might prefer negative feedback, and describes heuristics and learning mechanisms that lead to this behaviour. The four studies presented in this thesis expand our knowledge of how external and internal social contexts change our experience with rewards. They introduce computational models that aim to formalize such contextual influences, contributing to a more mechanistic understanding of these effects.

The ability to learn associations between events is of crucial importance for human and non-human animals. Without this ability we would be unable to identify when danger is imminent (e.g., the signs of a looming predator) or how to process the causal structure of our environment (e.g., understanding the role of causes and their corresponding effects). As such, it is essential to understand the factors which influence the formation of learned associations. Indeed, a plethora of studies have been conducted with this goal in mind and many models have been devised to elucidate the factors which influence how associative learning between events arises. A critical factor that a number of these models have identified concerns how the predictiveness of a cue, or a conditioned stimulus, can influence associative learning. For instance, studies have identified that a cue that has reliably predicted an outcome in the past, enters into subsequent associations better than a cue that has been an unreliable predictor of an outcome (e.g., the learned predictiveness effect; see Le Pelley & McLaren, 2003). The predictive ability of a cue can also interact with and influence learning about other cues. For example, prior learning about a cue and an outcome can block leaning between an additional cue and the same outcome, when these cues are presented together (i.e., blocking; see Kamin, 1968; 1969). Furthermore, simply presenting a cue in isolation or in compound – with no prior exposure to either – can also influence learning, with the elements of a cue compound entering into an association with an outcome to a lesser extent than a cue presented in isolation (i.e., overshadowing, see Pavlov, 1927). As such, a considerable amount of evidence has clearly identified the importance of the prior predictive ability of a cue and the extent to which cues can interact with one another to influence learning. However, much less research has explored the extent to which the predictability of an outcome can influence learning and the extent to which outcomes can interact with one another. Interestingly, key associative learning models assume that the prior predictability of an outcome should have no bearing on subsequent learning about this outcome, once separated from the cue which it was first paired with (e.g. Esber & Haselgrove, 2011; Le Pelley, 2004; Mackintosh, 1975; Pearce & Hall, 1980; Rescorla & Wagner, 1972). These models also assume that outcomes are unable to interact with other outcomes, when presented in compound, in the same manner as cues. This approach appears logical: cues can provide information which allows an organism to change its behaviour in anticipation of an event, therefore providing the organism with an evolutionary advantage. Consequently, it appears reasonable to suggest that the associability of cues can be modified based on their associative history or due to the presence of other cues. In contrast, however, when an outcome is presented the event of significance has already happened. As such, there appears to be no evolutionary advantage to the associability of an outcome being modified based on its prior associability, or the presence of other outcomes: once the event has happened it is too late for any advantage to be gained. Nevertheless, there is evidence to suggest that the prior predictability of an outcome can influence subsequent learning about this outcome. In light of this, Experiments 1 – 4 of Chapter 2 sought to further investigate whether the prior predictability of an outcome can influence subsequent learning about this outcome when separated from the cue which the outcome was first paired with. Experiments 1 and 2 revealed that participants learned better about a previously well-predicted outcome than a previously less well-predicted outcome, a finding which is inconsistent with key associative learning models. Experiments 3 and 4 respectively revealed that the concurrent predictability of the outcomes and Stage 1 training is important in obtaining this effect. Chapter 3 sought to assess whether the prior predictability of an outcome could influence subsequent learning about an additional outcome, when these outcomes were presented in compound. The experiments in this chapter employed an outcome blocking procedure using a food allergist task. In Experiment 5 an outcome blocking procedure was employed where an outcome compound was presented consisting of a previously well-predicted outcome and a novel outcome. In addition, an outcome compound was presented featuring a novel outcome and a surprising outcome. In this experiment an interaction effect was observed providing evidence to suggest that the prior predictability of an outcome can influence learning about other outcomes, as has been suggested by some other studies. In contrast to some previous studies in animals, however, an outcome facilitation effect was observed as opposed to the blocking effect which is typically – although not exclusively – seen in cues (cf. Batson & Batsell, 2000). Experiment 6 replicated this effect using a diagnostic task where the outcomes were causes and the cues were effects, thus demonstrating that the effect was present regardless of the type of judgement task participants completed. These findings are inconsistent with the predictions of causal model theory (e.g. Waldmann & Holyoak, 1992). Experiment 7 employed an additional type of control trial within the outcome blocking procedure employed in Experiments 5 – 6. When employing this additional type of control, which received exposure only in Stage 2, an outcome interaction effect was again observed. However, when this additional control trial was employed an outcome competition effect was observed in contrast to the outcome facilitation effect. Experiment 8 sought to tease apart two theoretical accounts derived from the Mackintosh model (1975) and the Standard Operating Procedures (SOP) model proposed by Wagner (1981) to account for the findings of Experiment 7. According to the Mackintosh account the effects reported in Experiments 5-7 should only be present following the second trial when the outcomes are presented in compound (i.e., when the associability of the cues have had an opportunity to be modified). The SOP account, however, stipulates that the effect should be present following the first trial. As such, Experiment 8 employed a one-trial outcome blocking procedure to test these accounts. This experiment provided partial support for the SOP account of the experiments reported in this chapter (whilst facilitation was observed amongst the outcomes competition was not). To further explore whether outcome interaction effects can be observed when additional types of procedures are employed, Chapter 4 sought to assess whether interaction effects could also be observed when outcome overshadowing and outcome relative validity procedures were employed. These experiments also used the food allergist task. In the outcome overshadowing experiment, both a single (i.e., elemental) outcome and a compound outcome (i.e., two outcomes) were reliably predicted. In the outcome relative validity task outcome compounds were presented which contained a common outcome (i.e., an outcome which was predicted by more than one cue) and unique outcomes. Some of these outcome compounds were reliably predicted and some were partially predicted. When an outcome relative validity procedure was employed no interaction effects were observed. One possible account of this finding is to suggest that both competition and facilitation effects were operating simultaneously, thus obscuring any differences. Yet, when an outcome overshadowing procedure was employed a competition effect was observed which is typically seen in cues. That is, an outcome which was presented alone was learned about better than when it was presented in compound with an additional outcome. Taken together these results provide evidence to suggest that the associative history of an outcome can influence subsequent learning about this outcome when separated from the cue which the outcome was first paired with. The results of Chapter 3 suggest that both facilitation and competition effects can be observed amongst outcomes, thus being similar to cues, which have also displayed both competition and facilitation effects. Although there was an absence of an interaction effect when a relative validity procedure was employed in Experiments 10 and 11 in Chapter 4, Experiment 9 of Chapter 4 also provides evidence to suggest that the associability of an outcome can interact with and influence subsequent learning about additional outcomes when an outcome overshadowing procedure is employed. As such, these experiments suggest that outcomes might be more similar to cues than originally conceived of in associative learning models. There are, however, several important factors to consider and methodological issues which arise when employing outcome associability and interaction procedures. The challenge of future work will be to identify the key factors which influence outcome associability, to understand the impact of this on key associative learning models, and to consider how outcomes are conceived of and distinguished from cues.

Humans have evolved to fuse information across senses by weighing the reliability of each modality (e.g., a viewer relies more on the picture to follow a drama if the TV audio is faulty; Ernst & Banks, 2002) as well as to infer unseen causes of sensory events by inverting internal generative models of the world (causal inference or CI: "Was the film dubbed or not?"). These multisensory strategies resemble Bayesian inference, but the mechanism whereby the inference unfolds step-by-step in a biologically plausible fashion remains poorly understood. Moreover, the reliability-weighted fusion and CI strategies have complementary costs and benefits, but sometimes seem to describe human choices in experimental conditions that presumably only satisfy the assumption of each particular strategy (e.g., De Winkel, Katliar, & Bülthoff, 2015; Meijer, Veselič, Calafiore, & Noppeney, 2019). In this thesis, I present converging evidence, from a series of human neuroimaging and psychophysics studies, suggesting that these rival accounts of multisensory inference can be reconciled by a time-resolved mechanism: The brain rapidly derives a fused sensory estimate for computational expediency and, later and if required, filtering out irrelevant signals based on the inferred sensory cause(s). First, analysing time- and source-resolved human magnetoencephalographic data (chapter 2), I unveil a systematic spatiotemporal cascade of the relevant computations for multisensory inference, starting with early segregated unisensory representations, continuing with sensory fusion in parietal-temporal regions, and culminating as CI in the frontal lobe. This suggests that the distinct computations required for flexible multisensory behaviour (fusion and CI) coexist, but each dominates at different times and in distinct regions (chapter 3). Furthermore, using behavioural paradigms such as speeded-judgement under deadline-induced time pressure as well as psychophysics leveraging sensory masking (chapter 4), I explicitly quantified how the unfolding of neural representations can be read out to drive behaviour. Collectively, slower versus faster behavioural choices reflect more of CI versus sensory fusion, respectively, indicating that the mapping from neural representational activity to behavioural choice corroborates the temporal hierarchy revealed in the neural data.

Replicability of research findings is a key issue in psychology, and has been the subject of considerable discussion by researchers. Replication is crucial to scientific principles, and underpins the consistency and verifiability of findings on which the foundation of scientific theories are built. Consistency of effects can be assessed through the perspective of heterogeneity, which indicates whether multiple research results into the same phenomenon are underpinned by the same true effect size. We use this perspective here to address concerns regarding replicability, and explore the application of heterogeneity in novel ways. This PhD project therefore aimed to: i) examine the heterogeneity of empirical findings in psychology; ii) consider the impact of biases in the research process on estimations of heterogeneity; iii) determine the strongest effects in psychology and their heterogeneity, and; iv) apply the perspective of heterogeneity to an existing psychological debate, the origin of psychological sex differences. In our first study, a re-analysis of 150 meta-analyses from cognitive, organisational, and social psychology was used to provide estimates of typical levels heterogeneity in psychology. This was compared to heterogeneity levels found across 57 multiple close replications. Our first study showed that low heterogeneity is achievable in psychology, but that typically heterogeneity estimates are high. Our next study used computer simulations to show that these levels of observed heterogeneity cannot be due to bias from questionable research practices or publication bias. In study 2, we showed the importance of including heterogeneity alongside effect size when interpreting an effect, and illustrated that even the largest mean effects in psychology might not be consistent in direction under conditions of high heterogeneity. Finally, in study 3 we showed that heterogeneity could provide an informative new perspective to the arguments regarding the origin of psychological sex differences. We explored several possible factors that could underlie heterogeneity in research findings, and suggest that unreliable forms of measurement and low quality of metaanalyses could provide promising avenues for further investigation in this regard. Overall, this thesis has provided an overview of the application of heterogeneity to provide a new perspective on psychological research.

It has been suggested that task-switching costs can be eliminated if participants memorise all stimulus-response mappings thereby avoiding task-switching altogether (Dreisbach, Goschke & Haider, 2006, 2007; Dreisbach & Haider, 2008). This has been labelled the “Look-Up Table” (LUT) approach. It has also been suggested that the LUT approach could potentially explain why animals such as monkeys (Stoet & Snyder, 2003; Avdagic et al., 2013) and pigeons (Castro & Wasserman, 2016; Meier, Lea & McLaren 2016) were able to perform task-switching without showing any task-switching costs (Dreisbach, et al., 2006, 2007; Dreisbach & Haider, 2008; Forrest, Monsell & Mclaren, 2014). In a series of eight experiments the following two questions were addressed: (1) Why do some participants show significant task-switching costs even when they do not switch between tasks (e.g., Forrest, Monsell & Mclaren, 2014)? (2) Can the LUT approach explain the absence of task-switching costs? In an attempt to answer both questions different sources of human task-switching costs are investigated in eight behavioural experiments. Chapter 1 provides an overview of different task-switching paradigms and accounts to explain task-switching costs. Chapter 2 summarises previous attempts to remove human task-switching costs. Evidence for the absence of task-switching costs in animals is also introduced. Following up on previous studies that suggested the LUT approach can explain the absence of task-switching costs, I conducted two task-switching experiments using visual tasks (i.e., colour task and shape task) with bivalent stimuli in an attempt to re-examine the conclusions of previous LUT studies (i.e., Dreisbach, et al., 2006, 2007; Dreisbach & Haider, 2008; Forrest, Monsell & Mclaren, 2014). The results in Chapter 2 indicate that human participants cannot always eliminate task-switching costs and do not always apply the LUT approach when the task-switching strategy is controlled. Therefore, the experiments in Chapter 3 and 4 sought to ascertain the requirements for eliminating task-switching costs when using the LUT approach. The experiments in Chapter 3 applied visual tasks where each task had a different stimulus-set. Experiments in Chapter 4 applied two classical mathematical tasks (i.e., big/small task, odd/even task) and used Chinese numbers as stimuli. The results of the experiments in Chapters 3 and 4 suggest that human participants must be able to give the correct answer without processing task-relevant features from the stimuli in order to eliminate task-switching costs. In the experiment of Chapter 5 the cue-stimulus-response mappings from Experiments 2.1 and 2.2 were rearranged so that switching between conventional tasks and rules became impossible. The results suggest that task-relevant features can trigger interferences thereby causing “task-switching costs” even when participants do not switch between tasks. In Chapter 7, I compare a modified interference account, introduced in Chapter 5, with the compound retrieval account (e.g., Logan & Schneider, 2010) and associative learning account (Forrest et al., 2014; Meier et al., 2016) in order to explain why human participants show task-switching costs even when they do not switch between tasks. I conclude that the modified interference account provides an alternative explanation. It has been proposed that only humans are affected by strong and long-lasting interference from previous trials during task-switching. As a consequence, this interference may explain why human participants consistently show task-switching costs whereas monkeys and pigeons show no task-switching costs.

Two central monoamine systems, dopamine and serotonin, are thought to be integral to the promotion or inhibition of goal-directed action respectively, but how this information is conveyed in tandem with reward-related signals is not yet fully understood. In particular, whilst reward prediction error encoding by midbrain dopamine activity and release is well replicated, this contrasts with a wealth of pharmacological evidence emphasising dopamine's role in activation of behaviour for reward. In Chapter 3, we establish a novel cue-instructed behavioural paradigm where animals must either enact or entirely restrain movement with the promise of receiving a small or large reward: the Go/No-Go task. We show that the phasic dopaminergic signal is shaped both by reward size on offer and by movement required to garner reward. To establish whether this phasic signal is causally driving behaviour, in Chapter 4 we systemically manipulate D1-like receptors - thought to be most sensitive to phasic dopamine release - to show that global modulation of this receptor mediates action initiation, inhibition, and execution, and biases action selection towards highly rewarding responses. In Chapter 5 the ability to initiate or inhibit cue-driven action exclusively is localised to D1-like receptors in the core of the nucleus accumbens. D2-like receptors have been considered important for the inhibition of action, but more recently it has been hypothesised that they may in fact work synergistically with D1-like receptors to promote reward-guided action. In Chapter 6 we show that these receptors indeed gate goal-directed behaviour, but only when movement is required. Finally, the serotonergic 5-HT2C receptor has been demonstrated as key to the ability to wait for reward but whether this is dependent on movement has not yet been explored. Therefore, in Chapter 7, we systemically and locally apply a 5-HT2C receptor ligand to show that disruption of this receptor's normal function reduces behavioural inhibition whilst simultaneously improving both speed and ability to enact goal-directed behaviour, but that the locus of these effects is extra-accumbens. In Chapter 8, we summarise these findings and discuss their implications for our understanding of how two of the brain's principal neurotransmitter systems, dopamine and serotonin, regulate motivated behaviour in the context of action and inaction.

The self bias effect refers to the prioritised processing of self-related information (i.e. faster RTs and higher accuracy) over information about others. This phenomenon has been widely observed across many areas of cognition such as memory, attention and perception. However, current knowledge of the self bias effect is still insufficient. This thesis utilises the perceptual matching paradigm as an experimental instrument to study the self bias effect in three main aspects. First, the impact of social experiences on self bias is examined. This thesis presents data that demonstrate the modulation of self bias as a result of three factors - cultural background, situational cues and major life developments. Comparisons of the self bias between independent and interdependent cultures reveal a difference in the self bias relative to strangers. Priming of interdependent frames of mind reduces the self bias relative to friend in people with low bias, which suggests individual differences in the magnitude of the self bias effect. The transition into motherhood, as a major life development, demonstrates a loss of the self bias effect due to maternal behaviour. Second, in the attempt to explain the robustness of the self bias effect, this thesis investigates the underlying mechanisms of self bias through parallel comparisons of self-related and reward-related stimuli using the perceptual matching task. To further explain the relationship between self and reward processes, electrophysiological responses are also examined with electroencephalogram (EEG) methods. The data demonstrate partial distinctions in the neural pathway that underlie self and reward processes. Third, social psychology methods, in addition to methods from experimental psychology, are used to study the self bias effect from another perspective. However, the data are unable to link the self bias effect with trait characteristics at this stage. This thesis contributes to current understanding of self-related processing by identifying the factors that modulate self bias and exploring the underlying mechanisms of self bias.

When making decisions under uncertainty, one common view is that people rely on simple heuristics that deliberately ignore information. One of the greatest puzzles in cognitive science concerns why heuristics can sometimes outperform full-information models, such as linear regression, which make full use of the available information. In this thesis, I will contribute the novel idea that heuristics can be thought of as embodying extreme Bayesian priors. Thereby, an explanation for less-is-more is that the heuristics’ relative simplicity and inflexibility amounts to a strong inductive bias, that is suitable for some learning and decision problems. I will formalize this idea by introducing Bayesian models within which heuristics are an extreme case along a continuum of model flexibility defined by the strength and nature of the prior. Crucially, the Bayesian models include heuristics at one of the Bayesian prior strength and classic full-information models at the other end of the Bayesian prior. This allows for a comparative test between the intermediate models along the continuum and the extremes of heuristics and full regression model. Indeed, I will show that intermediate models perform best across simulations, suggesting that down-weighting information is preferable to entirely ignoring it. These results refute an absolute version of less-is-more, demonstrating that heuristics will usually be outperformed by a model that takes into account the full information but weighs it appropriately. Thereby, the thesis provides a novel explanation for less-is-more: Heuristics work well because they embody a Bayesian prior that approximates the optimal prior. While the main contribution is formal, the final Chapter will explore whether less is more at the psychological level, and finds that people do not use heuristics, but rely on the full information instead. A consistent perspective will emerge throughout the whole thesis, which is that less is not more.

Mental health is distinct to emotional vulnerability, and can be characterised by wellbeing and functioning well in life. Cognitive-affective approaches have been widely used to investigate emotional vulnerability, however, research investigating the cognitive characteristics of mental health and resilience is in its infancy. Research in this thesis examined emotional information processing biases in positive mental health. Chapters Two and Three present cross-sectional data that support the continued exploration of the role of emotional cognitive biases in mental health. Chapter Two found associations between positive attention biases and psychological flexibility, and between the recognition of facially expressed emotions and mental health. Chapter Three found that the interrelationships amongst biases in attention, interpretation, and memory differed between high mental health and low mental health samples of adolescents. In Chapters Four and Five, attention bias modification was used to train attention bias towards positive information and away from negative information. Training-induced shifts in attentional bias were found to associate with positive emotions and happiness 12 weeks later in Chapter Four, but not in the replication and extension in Chapter Five. In Chapter Six a cognitive model of psychological resilience is introduced to draw together the largely disparate fields of emotional information-processing in emotional vulnerability, and resilience approaches. Chapter Seven was a proof-of-principle study of one hypothesis drawn from the cognitive model outlined in Chapter Six. Data from a novel attention bias alignment assessment task supported the hypothesis that individuals are capable of aligning attentional bias to threat as a function of whether displaying such a bias is adaptive or maladaptive in the current context. The studies in this thesis contribute to the understanding of emotional information-processing in mental health and resilience. Future studies investigating the adaptive directing of cognitive biases in differing contexts may be especially useful moving forward.

The influence of colour on cognition has a long and varied history in experimental psychology. Research areas include the influence of colour on; mate selection; food evaluation; mood; sporting prowess; and cognitive performance. However, few reliable colour based effects have emerged. This thesis examines a recently proposed effect in the domain of colour and cognitive performance; the "Red Achievement-Context Cognitive Effect" (RACE). This effect, proposed by Elliot et al., (2007), proposes that in an achievement context (i.e. one with a pass or fail outcome) red stimuli evoke avoidance motivation that, mediated through local processing, impedes cognitive ability. Although the RACE is recognised in the research literature and is underpinned by established theory, few direct replications of the RACE have been published and, applying criteria proposed by Pashler and Harris (2012), the literature that describes the RACE is susceptible to being skewed by publication bias. Additionally, there is a debate regarding whether the RACE emerges in both genders. This thesis contributes to the literature by addressing four aims; assessing the RACE in an applied context (aim 1); investigating the gender discrepancy within the literature (aim 2); providing independent, direct replications of the RACE in addition to conceptual replications (aim 3); and conducting a meta-analysis of published and grey literature (aim 4). A wide range of research methods were implemented including primary research using experimental methods in applied, online and laboratory settings and secondary research methods including meta-analysis and observational analysis of existing data sets. This thesis concludes that the RACE is a fragile effect that only emerges in very specific experimental settings and, even when the RACE does emerge, direct replications using identical methods do not always reproduce the effect. Whilst the RACE may manifest in controlled laboratory settings, it is unlikely to have any influence in applied settings.

Previous studies have shown that accessibility of conceptual information declines when sets of semantically-related items are presented repeatedly, although the underlying basis of this effect is debated – it is unclear if comprehension can decline without massed repetition of individual items, or if this effect is restricted to lexical retrieval in picture naming. Furthermore, declining comprehension has been characterised as arising from both ‘too much activation’ (i.e., on-going strong activation of competitors) and ‘too much inhibition’ (i.e., a failure to overcome inhibition which may facilitate the earlier retrieval of semantically-related targets). The thesis explored the impact of experimental manipulations (speed of presentation; strength of association between category and target item; modality of presentation; type of semantic decision required), on the magnitude of declining comprehension in healthy young adults. Comprehension declined even without individual item repetition, especially for strongly-associated targets (which may have accrued more competition or inhibition). The effect was found irrespective of presentation modality and more strongly at fast presentation speeds (when there was less time to overcome competition/inhibition). Next, the thesis examined the impact of ageing and semantic aphasia on changes in comprehension within the continuous categorisation paradigm. In these populations, controlled retrieval of conceptual information is thought to be weakened (relative to younger adults and healthy controls without aphasia). This should exaggerate declines in comprehension that reflect difficulty overcoming competition, but reduce the effect if it arises from the inhibition of competitors on earlier trials. The results were in line with the second hypothesis, since older adults and patients with semantic aphasia maintained their performance throughout the categories, unlike younger adults. Lastly, the thesis examined how this effect is modulated by transcranial electrical stimulation delivered to a key brain region implicated in semantic control – left inferior frontal gyrus (LIFG). Stimulation of LIFG attenuated the effect of declining comprehension, perhaps because initial retrieval was facilitated (potentially reducing the inhibition of related information), and/or because subsequent target selection was strengthened. Together, these results provide a more comprehensive account of what drives declining performance in continuous categorisation in healthy young adults who have the capacity to strongly engage semantic control.

This thesis investigates various deviations from rational beliefs by combining methods from psychology and experimental economics. The first two studies focused on the jumping-to-conclusions bias, where delusional and delusion-prone individuals tend to make decisions based on less data than controls. In an incentivised and adapted "beads task" probability-reasoning paradigm, the effects of delusion-proneness on decisions and on probability ratings were investigated. All participants, but especially more delusion-prone participants, made their decisions too early. Moreover, high delusion-prone participants' probability ratings were less affected by incentives than low delusion-prone participants'. The same paradigm was used to explore an inaccurate, but potentially evolutionarily advantageous, belief: the sexual over-perception bias, where men perceive more sexual interest in women's behaviour than women report or perceive. No evidence was found for men's over-perception of a male character's appeal to women in a belief-updating paradigm, which may reflect conceptual and methodological limitations of previous work on this topic. Perhaps, people deviate from rationality for certain purposes (e.g., evolutionary goals), while also holding an accurate, rational belief. The fourth study examined whether people are, at some level, aware that their optimistic beliefs are inaccurate, by combining two distinct belief-updating paradigms. Participants provided repeated answers to neutral questions and questions about undesirable future outcomes. Participants were equally accurate for neutral items, but were even more optimistic on the second guess for undesirable items, suggesting that optimism involves "real" self-deception. The last study investigated another phenomenon where people may want to avoid undesirable information. Investors are less willing to invest when playing the trust game with another player than when playing a computerised lottery with the same odds of the outcomes, which suggests that observing potential betrayal carries an additional, emotional cost. It was found that beliefs about others' trustworthiness could predict the level of such betrayal aversion.

Stanley Milgram’s obedience experiment is one of the most famous experiments in the history of psychology. This magnanimous statement, and so many others like it, is invariably followed by a claim that Milgram proved the majority of people will harm another person if instructed to do so by an authority figure. This thesis is a close and experiential reading of Milgram’s obedience to authority experiment conducted at Yale University between 1960 and 1963 not to ascertain the truth behind such claims but to accept them and build a narrative towards how they came to be. Milgram’s experiments are a complex and nuanced case study with which to examine the transferential relationship between science and culture. Taking the simulated shock generator as an omnipresent and invaluable aspect of Milgram’s laboratory apparatus, I introduce a specific way of seeing the paradigm: as a metaphorical model for critiquing the social world rather than measuring and generalising our role as agents within it. Incorporating a visual rhetorical approach mixed with design history, media studies and history of science, I also demonstrate the importance of fiction in methodological investigations in both history as well as social science. These directions help me answer the question of: what can we learn from looking at this well-worn subject from an object perspective; and what happens to a laboratory instrument when we take it out of its disciplinary enclave of empirical science? The result is an imminent critique about representational frameworks, the pursuit of knowledge and how we draw upon structures of investigation to simultaneously inform and critique the social world. My research draws heavily upon the Stanley Milgram Papers at Yale University, the Archive of the History of American Psychology at University of Akron, and Dramaco Instruments, a fictional and informative resource.

During search, individuals direct attention to potential targets and remember locations visited. Previously this has been examined in visual search paradigms, but this thesis investigates these mechanisms of attention and memory in large scale search. Participants searched a room containing an array of illuminated locations embedded in the floor. The participants' task was to press the switches at the illuminated locations on the floor to locate a target that changed colour when pressed. Across all experiments, the perceptual salience of search locations was manipulated by having some locations flashing and some static. Adults and children (Age 6-12) are more likely to search at flashing locations - their attention is captured by the salience of the flashing lights, leading to a bias to explore these targets (Chapter 2 Experiments 1-4). This effect is robust and does not show developmental progression from 6years of age through adulthood (Chapter 3 Experiment 1). Both adults and children are more able to equally explore flashing and static exploration to flashing locations when not required to remember which locations had been previously visited, indicating an interaction between memory and attention mechanisms during search. This finding builds upon established work of load theory of attention during visual search. Further evidence for this memory attention interaction comes from search tasks with concurrent digit span or auditory tasks (Chapter 2 Experiments 3& 4, Chapter 3 Experiment 2). Finally I examine ability to learn likely target locations (Chapter 4) and find that adults are more able and faster, to learn likely target locations among salient targets. Overall, this thesis provides an account of the strong interactions between attention and memory during large scale search, and how these processes develop. It builds upon a framework from visual search literature to understand how these processes function and develop in a larger search environment

This thesis investigates individual and interpersonal predictions of future affect and explores their relation to implicit theories of emotion, prediction recall, debiasing, and focalism. Studies 1, 2, and 3 assessed affect predictions to upcoming reasoning tests and academic results, and Studies 4, 5, and 6 concerned predictions for self-identified events. The first study investigated the influence of implicit theories of emotion (ITE; Tamir, John, Srivastava, & Gross, 2007) on impact bias and prediction recall manipulating ITE between participant pairs who predicted and reported their affective reactions to feedback on a test of reasoning skills. Neither impact bias nor recalled predictions were affected by the manipulation. Recalled affect predictions differed from original affect predictions, but were not influenced by experienced affect. Study 2 further investigated the effects of target event timing on impact bias and affect prediction recall. The results showed no differences between individual and interpersonal impact biases across conditions. Again, recalled predictions differed from original predictions, and were not influenced by experienced affect. Study 3 investigated the influence of prior information about impact bias on interpersonal affective forecasting involving real-world exam results. The results demonstrated no differences in predictions due to information, however, significantly less unhappiness was predicted for participants’ friends compared to self-predictions. Study 4 examined the effect of different de-biasing information on affective predictions. The results demonstrated no differences in affective predictions by condition and found that participants’ ITE were not associated to affect predictions. Study 5 examined individual and interpersonal affect predictions using a between-subjects design in place of the within-subjects design. The results demonstrated no differences between the affect predictions made for self and for friends, and ITE were not associated with predictions. Study 6 examined the impact bias in interpersonal affective forecasting and the role of focalism. The results demonstrated distinctions between individual and interpersonal affecting forecasting with individual impact bias for positive reactions for negative events and individual and interpersonal reverse impact bias for calm emotional reactions to positive events. Immune neglect was found not to be associated with predictions. Overall, the studies found evidence for similar individual and interpersonal predictions which are resistant to influence.

The main objective of this thesis was to examine gender differences in co-rumination using observational, experimental, and diary methods. At the start of this project there were no existing studies which had assessed co-rumination in this way and this thesis intended to be an exploratory investigation of co-rumination using these methods. Rose (2002) defined co-rumination as ‘excessively discussing problems within a dyadic relationship’ (p. 1830) and used it to explain why females have closer, more supportive, friendships (Rose & Rudolph, 2006) but are also more susceptible to depression (Weissman & Klerman, 1977). Her findings suggest that co-rumination has maladaptive outcomes for females (increased depression and anxiety) but not for males. The six studies within this thesis aimed to investigate the outcomes of co-rumination using adult (Studies 1- 4), adolescent (Studies 5 and 6) and child samples (Study 6). The first three studies within this thesis assessed co-rumination using dyadic analyses of observational and experimental data. The results of these studies indicated that scores from the co-rumination questionnaire (CRQ) and the co-rumination coding scheme (CRCS) were associated with affect, but that the co-rumination manipulation used in Study 3 had no effect on levels of affect. CRCS was mainly predictive of depressive outcomes whereas CRQ was predictive of both depressive and anxious outcomes. The research indicated that CRQ scores positively correlated across the two dyad members. However, each dyad member’s score showed different associations with affect, depending on whether the dyad member was presenting his or her own problem for discussion. The diary studies indicated that co-rumination was best assessed using daily items which were more predictive of changes in positive and negative affect than the CRQ. It was clear from the studies within this thesis that co-rumination did not only have negative outcomes for females, and that future research should examine the outcomes of co-ruminative discussions for males and females. It was suggested that future researchers should conduct similar experimental research to Study 3 but that they should include multiple co-ruminative interactions and more immediate assessments of co-rumination in the days following a co-ruminative interaction.

Rationale. Plain (or standardised) packaging would mean standardising the size, shape and colour of cigarette packs, removing all branding, leaving only the brand name in a standard font and location. In what have been predominantly qualitative studies, prior research has shown that plain packaging makes the health warnings more noticeable, reduces the appeal of the pack and prevents people from being mislead about the health risks of smoking. However, this research has been criticised by the tobacco industry for lacking in credibility. Methods. Using a series of experimental methodologies such as eye-tracking, attentional bi~s paradigms, brain imaging and randomised controlled trial design, the research conducted here is some of the first to use objective bio-behavioural measures to investigate the impact of plain packaging on visual attention and behaviour. Results. This research explores the attentional mechanisms underlying visual attention to cigarette packaging and finds that plain packaging can increase visual attention to health warnings among non-smokers and non-established smokers, but not among daily smokers, who actively avoid warnings. Furthermore, this research shows that even among dependent daily smokers, using plain packaging in the ' real-world' leads to changes in behaviour and attitudes to smoking. Conclusions. Overall, this thesis provides important information on how cigarette packaging can be used to increase attention to health warnings and more generally, on the mechanisms which guide attention to tobacco branding and health warnings. Beyond these scientific implications, the work conducted here has already had an impact on tobacco control policy. It was included in the European Commission's Tobacco Products Directive and has also been used by both the UK and Australian governments in their reviews of the evidence supporting plain packaging. These data support the view that plain packaging should be introduced in the UK.

This thesis addresses decision mechanisms in foraging situations, using laboratory experiments with European starlings (Sturnus vulgaris). Building on previous work from the Behavioural Ecology Research Group, I chose the Sequential Choice Model (SCM; reviewed in Kacelnik et al., 2011 − Appendix 1) as a starting point, and tested its premises and predictions generalising it to different experimental protocols. Classical decision models do not relate choice preferences to behaviour towards isolated options, and assume that choices involve time-consuming evaluations of all alternatives. However, previous work found that starlings’ responses to isolated options predict preference in choices, and that response times to single-option encounters are not reliably longer than response times in choices. Since, in the wild, options are normally encountered sequentially, dealing with isolated options can be considered of greater biological, and possibly psychological, significance than simultaneous decisions. Following this rationale, the SCM postulates that when multiple simultaneous stimuli are met they are processed in parallel, each competing against the memory of background opportunities, rather than comparing present options to each other. At the time of launching this research, these ideas had only been applied to protocols involving just two deterministic alternatives and offering no chance to explore the influence of learning history (i.e., how animals learn to choose; see Chapter 4). To increase their relevance and offer more rigorous tests, I generalised them to situations with multiple (see Chapters 2, 4 and 5), and in some cases probabilistic alternatives (see Chapter 3), controlling the learning regime. I combined these extensions with tests of economic rationality (see Chapter 6), a concept that is presently facing sustained debates. Integrating the result of all experimental chapters (see Chapter 7), my results support the notion that behaviour in single-option encounters is fundamental to understand choice behaviour. The important issue of whether choices involve a decision time cost or the opposite, a shortening of response times, remains unsolved, as neither could be evidenced reliably.

This thesis aims to investigate the secondary transfer effect of contact, a phenomenon whereby contact with one outgroup leads to improved attitudes towards other, non-contacted outgroups. While evidence mounts for the existence of secondary transfer effects, its underlying mediation processes remain poorly conceptualised and thus, poorly understood. Thus, in this thesis, I aimed to clarify the conditions under and the processes by which the secondary transfer effect works. Chapter 1 introduces intergroup contact theory and traces its development from the contact hypothesis (Allport, 1954) to the uncovering of the secondary transfer effect. Based on theory from all aspects of intergroup contact research, Chapter 1 proposes a theoretically reformulated approach to understanding the deprovincialization hypothesis by way of (1) diversity beliefs, (2) the development of a multicultural outlook on intergroup relations, and (3) a more nuanced understanding of when ingroup identity is likely to relate ethnocentrically to outgroup attitudes. Point three more specifically looks at the role of social dominance orientation as a moderator of the relationship between ingroup identification and outgroup attitude. Chapter 1 also provides an extension to the attitude generalization hypothesis by considering the role that similarity gradients play. Chapter 2 discusses methodological considerations important to the analysis strategy used throughout the thesis. Six empirical investigations across three contexts—England (Studies 1 and 2), Northern Ireland (Studies 3 and 4) and South Africa (Studies 5 and 6) set out to test the secondary transfer effect and the hypotheses offered in Chapter 1. Across three cross-sectional studies (Studies 1, 2, 3, and 4), a three-wave longitudinal study (Study 5) and an experimental study (Study 6), I was able to show the following: (a) that attitude generalization is a robust mediator of the secondary transfer effect (Studies 1, 2, 3, 4, and 5); (b) similarity gradients qualify the attitude generalization process such that attitudes generalize more strongly between outgroups that are perceived to be similar (Studies 3, 4, and 5); (c) that diversity beliefs (Study 2) and multiculturalism (Study 4), as alternative interpretations of the deprovincialization effect, mediate the secondary transfer effect; (d) social dominance orientation moderates the relationship between ingroup identification and outgroup attitude (Study 3); (e) that the deprovincialization and attitude generalization hypotheses are not independent, but rather interrelated processes of the secondary transfer effect (Studies 2, 3, and 4); (f) that experimentally manipulated forms of extended contact can lead to the secondary transfer effect because group categories and membership are made salient during the extended contact experience (Study 6); and (g) that it is contact that leads to wider attitude generalization rather than less prejudiced people seeking contact from a wider pool of social groups (Study 5). Furthermore, owing to their three-wave longitudinal (Study 5) and experimental (Study 6) designs, these two studies provide the most convincing evidence of the causal nature—from contact to reduced prejudice—of the secondary transfer effect to date. Taken together, these six studies provide a wealth of critical support for the secondary transfer effect as well as for the reformulated deprovincialization and the extended attitude generalization hypotheses.

The main objective of this thesis was to investigate the proposition that moral emotions act as antecedents of political attitudes. My approach (Chapter 1) stems from moral foundations theory, which proposes that liberals and conservatives have different moral values (Graham, Haidt, & Nosek, 2009). Chapter 2 presents Study 1, an experimental test of the hypothesis that induced disgust leads participants to adopt more left-wing economic attitudes in comparison to a control condition (sadness). Results supported this hypothesis. Chapter 3 reviews emotion-regulation theories, and presents Study 2, which investigated whether emotion-regulation strategies, disgust sensitivity (DS-R), and private body consciousness (PBC) moderate the effects found in Study 1. As predicted, disgust led to more left-wing economic attitudes, but this was only the case for high-PBC and high-DS-R participants. Chapter 4 presents Study 3, which replicated Study 2, and showed dissociations between the effects of disgust on economic and social attitudes. Chapter 5 presents a cross-sectional investigation (Study 4) that tested for associations between the predisposition to experience disgust and both social and economic attitudes. As predicted, core disgust and pathogen disgust were associated with left-wing economic attitudes and these effects applied only to British participants, and not non-British participants. Chapter 6 presents Study 5 – an experiment investigating the relationship between disgust and prejudiced attitudes towards outgroups. Induced disgust led to more prejudiced attitudes towards a novel group than both sadness and neutral emotion. Chapter 7 is focused on two self-conscious moral emotions: guilt and shame. Study 6, presented in this chapter, found a positive association between guilt proneness and left-wing economic attitudes, and a relationship between shame proneness and social-conservative attitudes. Study 7 failed to reveal causal relationships between incidental guilt and shame and political attitudes. Chapter 8 presents the general discussion addressing limitations, implications, and future research directions.

During multisensory integration, information from distinct sensory systems that refers to the same physical event is combined. For example, the sound and image that an individual generates as s/he interacts with the world, will provide the nervous system with multiple cues which can be integrated to estimate the individual’s position in the environment. However, the information that is perceived through different sensory pathways/systems can be qualitatively different. The information can be redundant and describe the same property of an event in a common reference frame (i.e., the image and sound referring to the individual’s location), or it can be complementary. Combining complementary information can be advantageous in that it extends the range and richness of the information available to the nervous system, but can also be superfluous and unnecessary to the task at hand – i.e. olfactory cues about the individuals perfume can increase the richness of the representation but not necessarily aid in localisation. Over the last century or so, a large body of research has focused on different aspects of multisensory interactions at both the behavioural and neural levels. It is currently unclear whether the mechanisms underlying multisensory interactions for both type of cue are similar or not. Moreover, the evidence for differences in behavioural outcome, dependent on the nature of the cue, is growing. Such cue property effects possibly reflect a processing heuristic for more efficient parsing of the vast amount of sensory information available to the nervous system at any one time. The present thesis assesses the effects of cue properties (i.e., redundant or complementary) on multisensory processing and reports a series of experiments demonstrating that the nature of the cue, defined by the task of the observer, influences whether the cues compete for representation as a result of interacting, or whether instead multisensory information produces an optimal increase in reliability of the event estimate. Moreover, a bridging series of experiments demonstrate the key role of redundancy in inferring that two signals have a common physical cause and should be integrated, despite conflict in the cues. The experiments provide insights into the different strategies adopted by the nervous system and some tentative evidence for possible, distinct underlying mechanisms.

This thesis examines the factors (e.g., task load, distractor features, or individual differences) that determine the extent to which individuals are distracted and the manner in which these factors interact. In particular, established theories of attention are applied to two understudied forms of distraction common to daily life: distraction by entirely task-irrelevant external stimuli and internal distraction from unintentional task-unrelated thoughts (i.e. mind-wandering). The experiments reported in this thesis establish a new measure of distraction by entirely task-irrelevant stimuli, drawing on the attentional capture literature to demonstrate that this form of distraction can occur in the absence of any top down attentional settings relating to the distractor or task features. It is also demonstrated that both of this form of distraction and also mindwandering can be modulated by the level of perceptual task-load – an established determinant of other forms of distractor processing. In this manner the thesis integrates two previously separate bodies of literature on selective attention and mind-wandering. In addition, individual differences in both internal and external forms of distraction are shown to be correlated, suggesting a common underlying trait influencing susceptibility to distraction both from internal sources (in the form of mind-wandering) and from external task-irrelevant distractor stimuli.