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Interpersonal power, defined as the asymmetrical control over valued outcomes, has important effects on the way cognitive processing unfolds. This work explores the effect of power on basic cognitive processes, in addition to broader processes that appear at the level of social behaviour. I begin this thesis with an introductory chapter, followed by a chapter describing the theory and practice behind electro-encephalogram recordings. In Chapter 3, I explore the effect of power on attention selection using a task that requires the ability to focus or divide attention in space, while varying the amount of distractors. The results suggest that low-power participants (subordinates) are more susceptible to the presence of distractors, regardless of whether the task necessitates focused or divided attention. In this context, inhibition accounts for the results to a greater extent than spatial orienting. In Chapter 4, I explore the effect of power on early inhibition processes in the context of executive control, in a task which allows participants to allegedly observe each others’ performance and receive feedback. The results show that high power is associated with reduced behavioural accuracy on trials that require executive control. Event-related potential analyses show that power-holders devote reduced motivational resources to their targets compared to subordinates, but do not differ at the level of early conflict detection. Their feedback potential results show a greater expectation of rewards, but reduced subjective magnitude attributed to losses. Subordinates, on the other hand, are asymmetrically sensitive to power-holders’ targets. They expect fewer rewards, but attribute greater significance to losses. In Chapter 5, I show that subordinates are asymmetrically competent at remembering diagnostic choices made by power-holders. In a final general discussion chapter, I integrate the findings of the experiments, which point to multi-layered effects of power, conferring those who possess it and those who lack it with distinct cognitive processing styles that suit their adaptive needs. The results are consistent with a hypothesized link between subordination and up-regulation of vigilance and environmental sensitivity. Limitations and future directions are discussed.

The current thesis explores the complex relationship between cognitive control and memory. A series of experiments combined task-switching paradigms with recognition memory tests to measure how switching between tasks influences effective control over long-term memory. In these experiments, participants were presented with compound stimuli consisting of a picture and an overlaid word, and were cued in each trial whether the word or the picture was relevant (attended) or irrelevant (unattended). Participants were then tested for their memory of items presented during task switching. Experiments 1-2 indicated that switching between tasks reduces the selectivity of processing: Switching was associated with impaired task performance as well as more similar memory ratings for attended and unattended items. Experiments 3-5 extended these findings by showing that enhanced top-down control positively affected task-performance as well as memory, in both cases by increasing the selectivity of processing toward task-relevant information. Experiments 6-7 replicated key effects with simple switches of visual attention, and explored the neural correlates of successful task performance and encoding using EEG. The key finding here was that previously observed ―subsequent memory‖ effects reflect, at least in part, selective encoding processes. The last chapter extended the focus of the investigation to explore the role of control in long-term memory retrieval. FMRI meta- analyses indicated considerable overlap in neural activation found during task switching and during the adoption of different retrieval sets. The results of Experiment 8 indicated that switching during task performance and later memory retrieval were both associated with decreased selectivity of processing. Collectively, the results of this thesis suggest that selectivity of processing is a critical factor in effective task performance and successful memory, with potentially very similar mechanisms underlying the two. This work demonstrates the fruitfulness of combining research on cognitive control and memory to study questions relevant for both fields.

The physical properties of the distal stimuli activating our senses are often correlated in nature; it would therefore be advantageous to exploit such correlations to better process sensory information. Stimulus correlations can be contingent and readily available to the senses (like the temporal correlation between mouth movements and vocal sounds in speech), or can be the results of the statistical co-occurrence of certain stimulus properties that can be learnt over time (like the relation between the frequency of acoustic resonance and the size of the resonator). Over the last century, a large body of research on multisensory processing has demonstrated the existence of compatibility effects between individual features of stimuli from different sensory modalities. Such compatibility effects, termed crossmodal correspondences, possibly reflect the internalization of the natural correlation between stimulus properties. The present dissertation assesses the effects of crossmodal correspondences on multisensory processing and reports a series of experiments demonstrating that crossmodal correspondences influence the processing rate of sensory information, distort perceptual experiences and lead to stronger multisensory integration. Moreover, a final experiment investigating the effects of contingent signals’ correlation on multisensory processing demonstrates the key role of temporal correlation in inferring whether two signals have a common physical cause or not (i.e., the correspondence problem). A Bayesian framework is proposed to interpret the present results whereby stimulus correlations, represented on the prior distribution of expected crossmodal co-occurrence, operate as cues to solve the correspondence problem.

This thesis expands our understanding of the role of several different mating behaviours in the process of forming and maintaining human mating pair-bonds. Chapter 2 investigated within-sex mating strategies and found that their distribution reflects the presence of two phenotypes, one favouring the pursuit of short-term mating and one the establishment of mating pair-bonds, each driven by prenatal testosterone exposure. Chapter 3 investigated the possible functional role of kissing in mating relationships, and found that it was utilised divergently by individuals pursuing different mating strategies, with those interested in short-term mating utilising it to assess the suitability of potential mates at initial relationship stages, and those interested in long-term mating using it to mediate pair-bond attachments. Chapter 4 examined female attitudes towards kissing across the menstrual cycle and found that attitudes varied with cycle phase, mediated by fluctuations in the hormone progesterone. This chapter also investigated the effects of kissing-related information on mate assessment and found that such information influenced mate desirability, even in the presence of typically dominant visual cues. Lastly, Chapter 5 investigated the cognitive effects of established pair-bonds, finding that individuals ‘in love’ with a mating partner show improved empathising abilities, particularly males when it comes to assessing negative emotional states in others. Using an evolutionary framework, each chapter of this thesis contributes novel insights to our understanding of these diverse behaviours. These results suggest that that future research must take into account within-sex phenotypic differences in order to truly understand human mating strategy decisions, and that different mating strategy phenotypes might adaptively utilise the same courtship behaviours in divergent ways. Furthermore, these results also suggest that pair-bonding in humans may be a relatively recent phenomenon, and that the formation of such pair-bonds can have adaptive cognitive effects for males within such bonded relationships.

Re-experiencing trauma in the form of intrusive, image-based memories (here referred to as flashbacks) is a hallmark symptom of Post-Traumatic Stress Disorder (PTSD). There are successful treatments available for full-blown PTSD; however, these can only be administered one month post trauma. There are limited interventions that can be administered to reduce flashbacks in the early aftermath of trauma. The overarching aim of this thesis was to use an experimental psychopathology approach, the trauma film paradigm, to investigate the reduction of flashbacks post-trauma using the cognitive task, Tetris. Chapter 1 provides a literature review of experimental research that has used the trauma film paradigm. Chapter 2 reviews experimental work on disrupting memory reconsolidation in humans. Chapter 3 details pilot work on the development of an experimental protocol based upon these literature reviews. Experiment 1 (Chapter 4) investigated disrupting reconsolidation for a 24 hour old analogue trauma (aversive film material) using the cognitive task, Tetris. A procedure designed to disrupt flashback reconsolidation (a memory reactivation task for the film followed by playing the computer game Tetris) was compared with a no-task Control. Compared to Control, those in the Tetris condition reported fewer flashbacks to the film in an intrusion diary across the subsequent week and on convergent measures of flashback frequency. Experiment 2 (Chapter 5) provided a test of replication for findings from Experiment 1, in addition to extending findings by dismantling the procedure’s component parts. Participants who underwent Tetris only (without memory reactivation) or memory reactivation (without Tetris) did not demonstrate a reduction in flashbacks and were comparable to the no-task control condition. Both a memory reactivation task plus Tetris in combination were critical for reducing subsequent flashbacks for a consolidated memory for a trauma film. Experiment 3 (Chapter 6) tested whether playing Tetris could help disrupt flashback memories for an analogue trauma (film) if administered prior to film viewing, relative to a no-task control condition. Results showed that playing Tetris before a trauma film did not reduce flashbacks, as demonstrated via an intrusion diary and convergent flashback measures. Chapters 7 reviews email feedback relating to playing Tetris after experiencing real-life adversity from members of the public. Chapter 8 explores a form of treatment for trauma in a NHS, complex patient setting. Chapter 9 discusses the findings from all chapters with reference to their implications and limitations, and new directions for future research. Overall, findings using analogue trauma suggest that memory reactivation followed by playing Tetris may be promising for development as a post-trauma ‘cognitive vaccine’ to disrupt the both the consolidation and potential reconsolidation of flashback memories.

People turn to others for help and advice during hard times. Early psychologists suggested a ‘talking cure’ as a remedy for emotional turmoil (e.g., Freud, 1916–7/1963; Rogers, 1942). Likewise, folk psychology often sees heart-to-heart conversations as a win-win proposition that brings relief to the afflicted person and reinforces social bonds at the time of need. However, talking about problems does not always help (e.g., Rimé, 2009; Rimé, Mesquita, Boca, & Philppot, 1991; Rimé, Philippot, Boca, & Mesquita, 1992; Rose, 2002). In some cases, problem-talk can be a lose-lose proposition that drags both discussants into depression (Rose, 2002; Rose, Carlson, & Waller, 2007). This thesis examines co-rumination (Rose, 2002), a case of emotional sharing that hurts people instead of helping them, on three levels of analysis (individuals, dyads, and groups). At the individual level, I sketch the life course of co-rumination and replicate earlier findings of gender differences. Furthermore, online survey data (N = 464) links co-rumination with agreeableness and neuroticism. I also demonstrate that co-rumination can be assessed with a brief measure that is 66% shorter than the original. At the dyadic level, data from recorded conversations between romantic couples show that face-to-face co-rumination influences people’s real-time emotional trajectories in complex ways. Furthermore, observer-ratings of the conversations suggest that third-parties can detect co-rumination, even from silent videos. Finally, I study how people react to others’ negative mood and co-rumination in a real social context by longitudinally following two cohorts of students and modelling their interactions with social network analysis tools. These models show that co-rumination appears to elicit social rejection from others, implying a possible pathway to depression via loneliness imposed on the co-ruminators.

This thesis investigates the strategies infants use to generalise labels to different objects in the early stages of lexical development. It aims to directly test the assumption that a taxonomic bias exists which guides infants to extend words to categories of objects instead of individual instances of them, against the hypothesis that infants discover the extension of words through exposure to multiple naming instances of different objects.Experiments One and Two attempted to teach two object-label pairings to infants at the end of their first year of life, and test generalisation of those labels to new objects from the same adult linguistic categories. This aim failed because infants showed evidence for prior knowledge of the words. Experiments Three and Four employed a more infant-controlled procedure using a habituation task during training; in the former a single exemplar from each adult category was used, whereas in the latter multiple exemplars from each category were used. In both Experiments evidence for word learning was provided at test, but infants failed to generalise the labels to other objects. Experiment Five used a training phase identical to Experiment Four but tested infants for perceptual categorisation in the absence of any labels. Some infants showed evidence for their ability to create such categories on the basis of the training set, suggesting that the inability to generalise in Experiments Three and Four was not due to a perceptual limitation. These findings suggest that infants at the end of their first year do not seem to be guided by any linguistic biases in their generalisation of labels. This thesis concludes that 10-month-old infants seem to have more advanced linguistic abilities than has previously been thought and constraint-like behaviour in later stages of lexical development might be a result of experience instead of a qualitative shift in cognitive processes.