In the present dissertation, I assessed the visual hierarchy stages that support the visual perception of three-dimensional (3D) surfaces. In the first experimental chapter, I used fMRI-guided rTMS to probe the cortical areas involved in the perception of slanted surfaces. Results hint at a functional contribution of the dorso-parietal visual stream (posterior parietal cortex; PPC) to slant estimation, however, further work is needed to fully understand the nature of its involvement. I then showed that fMRI-guided rTMS-induced disruption of the ventral stream (area LO) eliminates the facilitation observed, in 3D surface discrimination, when disparity and motion cues congruently inform depth. This finding indicates that LO encodes signals for the integration of depth cues. Then, I showed rTMS evidence that disparity and orientation signal-in-noise discriminations causally relate to PPC’s function. Interestingly, this relation diminishes after training on a visual feature other than the one employed during rTMS testing. This finding indicates that training, even across visual features, can influence neuronal organization. Finally, I used backward masking to show that brightness masking incorporates the 3D information of disparity-defined slant. This finding suggests that brightness estimation is mediated by mid-level neuronal mechanisms, at a cortical stage where binocular signals have been combined.

In synaesthesia a sensation in one modality triggers a consciously perceived sensation in another sensory modality or cognitive domain. In this thesis we investigate auditory sensation that are induced by dynamic visual stimuli, akin to hearing-motion synaesthesia (Saenz and Koch, 2008). We term this the Visually-Evoked Auditory Response (vEAR). We first establish the prevalence of vEAR in a random sample, with questionnaire responses indicating a higher prevalence (as many as 1 in 5) than canonical synaesthesias. We report that those who experience vEAR showed better performance compared to controls when discriminating between ‘Morse-code’ style rhythmic sequences in the visual domain, as did Saenz and Koch (2008). We also demonstrate that vEAR is perceptually real enough to interfere with hearing real world sounds. We then demonstrate that in control subjects Transcranial Alternating Current Stimulation (TACS), when applied over the temporal versus the occipital lobes, impairs auditory versus visual sequence discrimination respectively. However, temporal TACS improved visual and occipital TACS improved auditory sequence discrimination performance. This suggests the presence of normally-occurring mutual alpha-mediated competitive inhibition of the two cortices. This TACS effect was not seen in individuals with vEAR, indicating that their auditory and visual cortices are able to cooperate to perform the task despite disruption from TACS. Finally, we investigate the types of visual stimuli that best evoke vEAR, and the types of people who tend to experience it. We conducted a large online survey in which respondents rated the amount of vEAR evoked by a series of silent videos depicting types of motion. The predictiveness of a real-world sound was identified as a major contributor to ratings in all respondents, while motion energy (raw changes in light over space and time) specifically influenced ratings in those who experience vEAR. We also report demographic and trait questions relating to auditory perception that predict higher ratings, including the frequency one experiences music imagery in their head, or whether they have tinnitus or types of synaesthesia. We conclude that vEAR results from both high and low-level connectivity between the visual and auditory cortices and an atypical inhibition of these connections.

This thesis addressed three questions regarding our tendency to prioritise recently learned self-associations. Following an overview of cognitive self-biases in Chapter 1, Chapter 2 explored how novel self-associations impact higher-level social cognition, namely, visual perspective taking (VPT). In Experiments 1–3, we examined how participants respond to third-person perspectives (3PPs) associated with self and other. Participants showed superior performance when explicitly targeting a self-associated (vs. other-associated) 3PP. Chapter 3 extended this line of research by examining whether these self-bias effects are related to social-cognitive ability and executive function. In Experiments 4–5, we found that both individual differences in empathy and putative age-relevant motivations reliably modulated self-bias in third-person VPT. These findings suggest that VPT paradigms draw on domain-specific and domain-general capacities. Chapter 4 examined the extent to which interpersonal dimensions (e.g., day-to-day personal relevance and valence) may explain self-tagging effects. Using behavioural and fMRI methodology, Experiments 6–8 showed that self-processing was largely independent of responses to relevance and valence in others. Finally, Chapter 5 provides a broader discussion of findings from the preceding chapters, offering some possible future research directions.

This thesis examines vision testing and visual training in sport. Through four related studies, the predictive ability of visual and perceptual tests was examined in a range of activities including driving and one-handed ball catching. The potential benefits of visual training methods were investigated (with particular emphasis on stroboscopic training), as well as the mechanisms that may underpin any changes. A key theme throughout the thesis was that of task representativeness; a concept by which it is believed the more a study design reflects the environment it is meant to predict, the more valid and reliable the results obtained are. Chapter one is a review of the literature highlighting the key areas which the thesis as a whole addresses. Chapter’s two to five include the studies undertaken in this thesis and follow the same format each time; an introduction to the relevant research, a methods section detailing the experimental procedure, a results section which statistically analysed the measures employed, and a discussion of the findings with reference to the existing literature. Finally, in chapter six the strengths and limitations of the thesis are considered, before suggestions are made for future studies, and concluding remarks made.

Three event-related potential (ERP) experiments investigated the spatial-verbal dichotomy (emphasized by Baddeley’s model of working memory), selective attention (emphasized by Cowan’s model), and sub-processes in n-back tasks. The studies provide a basis for further clinical research on Alzheimer’s disease. Experiment 1 studied the spatial-verbal dichotomy using n-back tasks with top-down control. It used identical stimuli in both spatial and verbal tasks, and was designed to eliminate interference from perceptual processes. The spatial and verbal tasks differed only in the instructions given before the tasks. Using a model of the task, sub-processes involved in n-back tasks were delineated and analyzed by difference waveforms of ERPs. Domain-specific lateralization was found in a shift sub-process but not in a replacement sub-process. Because information from the irrelevant domain could not be totally excluded by top-down control (which distinguished the spatial and verbal tasks), Experiment 2 recorded information from irrelevant domains. Interactions between irrelevant and relevant domains were found in ERP difference waveforms. Therefore, the results of Experiment 2 suggest that selective attention is unable to exclude interference from the irrelevant domain. Following this conclusion, Experiment 3 adopted a data-driven (bottom-up controlled) methodology, and used different stimuli in spatial and verbal domains in contrast with Experiment 1. In Experiment 3, selective attention was not needed to distinguish spatial tasks from verbal tasks because the spatial and verbal stimuli were different. A different pattern was obtained in Experiment 3; domain-specific lateralization was found only in the replacement sub-process (and not in the shift sub-process). Relationships among n-back task sub-processes, i.e., matching, replacement and shift were determined in advance by logical analyses. From this model, process-specific patterns of domain-specific lateralization, where domain-specific lateralization should exist in the shift sub-process of a conceptual task and in the replacement sub-process of a data-driven task, were predicted under conceptual and data-driven control. The results in Experiment 1 and 3 fitted these predictions, consistent with the proposed logical hypothesis of sub-processes. The similarity between match-specific and domain-specific lateralization suggests avenues for further studies. Using the framework of the model developed here, further investigation could be carried out at the sub-process level using the high temporal resolution of ERPs to decipher the detailed steps of processing that our brains execute in working memory tasks.

Jeannerod (2006) proposed that imagined movements are effectively covert simulations of their physical counterparts. Consistent with this idea, imagined movements show adherence to the same behavioural and body constraints as physical movements, activate similar cortical and subcortical regions, and can even excite corticospinal pathways. Although postural control is inherently linked to the performance of all movements, its interaction with imagined movements has received little research attention, with the few studies that have been conducted predominately looking at imagery of the lower limbs that are simultaneously engaged in posture control. The present research is the first to study interactions between posture control and imagined upper limb movements. In a series of experiments, healthy young adults performed imagined reaching movements of the arm to an array of target locations presented either in the mediolateral or anteroposterior direction. Participants’ stability in the mediolateral direction was manipulated through varying stance. The effects of different arm movement parameters (e.g., load and precision) were also considered, as was the congruency between physical and imagined stance. Cumulatively, the present experimental results suggest that the current postural state does influence trajectory planning during imagined arm movements and furthermore, there are observable changes in posture control in response to imagined upper limb movements. These findings have important implications for our understanding of the processes involved in inhibiting overt movement during motor imagery. They also contribute to the development of motor-imagery based schemes of motor training and rehabilitation.

Top-down expectations allow us to quickly filter relevant events from the continuous stimulation by the environment. The Attentional Blink (AB) paradigm simulates such taxing situations in the laboratory (Raymond et al., 1992). For the first time, I employed composite events as targets in an AB paradigm. A first target (T1) was defined as 3 consecutive digits, while a second target (T2) was an ‘X’. In this way, unfulfilled expectations regarding T1 could be elicited by presenting partial targets, containing only 1 or 2 digits. My paradigm was specifically developed to allow the manipulation of global and local expectations independently. While global expectations are induced by relative trial frequencies and modulate target expectations prior to a trial, local expectations are induced by the consecutive presentation of digits that raise the expectation for a full target as a trial unfolds. I predicted that, when expectation for the full target was globally high and locally raised to a maximum, disappointing these expectations would result in an AB in itself without a full T1 being presented (i.e. with 2 digits). Possibly, this AB could be even larger in magnitude than when expectations are met (with 3 digits). This was indeed the case when 3 digit trials were the most frequent event (Experiments 1, 3, 4 and 5). When global expectations for 3 digits were high, I observed the strongest AB with 2 digits, greater even than with the full T1. This suggests that maximally raised but violated expectations (with 2 digits) have a more detrimental effect on subsequent T2 processing than fulfilled expectations for the full target (3 digits). I subsequently showed that this pattern could not simply be explained by enumeration of the digits (Experiment 2). Counting the digits was associated with the same blink magnitude with 1, 2 and 3 digits, suggesting that counting involves consolidation of digits into working memory as targets, a process unaffected by global expectation of trial types or the quantity of digits. I then investigated the role of bottom-up signals in switching from raised expectations for the T1 to T2. I considered the roles of the post digit mask (Experiment 3), and of colour- (Experiment 4) and sound-based (Experiment 5) switching signals which marked the end of the digit event. Performance was improved considerably by removing the lag 1 mask after partial targets (1 digit and 2 digits), but not after full targets (3 digits). For partial targets, the presence of a mask seems to conflict with the expectations for another digit, and the knock-on effect could be a delay in switching to T2. The AB magnitude for full targets is unaffected by the mask, suggesting consolidation of T1 and switching to T2 occurs immediately after the 3rd and final digit. On the other hand, marking the final digit with a colour or sound did not influence the AB in any digit condition. Taken together, this suggests that in this paradigm, top-down expectations play a much stronger role than bottom-up factors. I then manipulated the relative frequencies of the digit events to investigate how top-down global and local expectations contributed to the AB magnitudes. In Experiments 6 and 7, the 3 digit event became increasingly rarer as the 2 digit event became more frequent. Overall, I found a reversal of the previous pattern: The AB with 3 digits became increasingly stronger than the AB with 2 digits. My findings suggest that global expectations influence the build up of local expectation increments with each presented digit, yet this occurs in a non-linear fashion. Two MEG experiments further show that raised and subsequently violated expectations for T1 have a distinct neural signature (MEG Experiment 1), which cannot be accounted for by the act of counting the digits (MEG Experiment 2). In particular, beta-band oscillations seem to code for both the target processing and the rapid changes in local expectations during the trial. A key finding from MEG Experiment 1 was the similar widespread beta power decrease for 2 digits and 3 digits until 0.6 s, when the conditions dissociated into a frontal power increase for 2 digits while the 3 digit power decrease continued. Tentatively, I suggest that this could represent the building of expectations for the full target (power decrease) and the subsequent violation of expectations (frontal power increase) in the 2 digit trials. An M300 to each digit suggests that all digits enter the global workspace and are consolidated into working memory; a finding which is corroborated by the theta-band results. Meanwhile, alpha oscillations were more posterior and appear to code for the processing of full targets only (3 digits in MEG Experiment 1, and 1, 2 and 3 digits in MEG Experiment 2). To summarise, my key finding is that an AB can be elicited without a T1 actually occurring. Building up expectations about the T1 event within a trial can alone induce an AB. Furthermore, built and subsequently violated expectations for the T1 event seem to be coded in the brain by widespread modulations of beta oscillations. I discuss the findings with relation to several models of the AB. In particular, my behavioural and MEG findings fit well with the “Robust State” hypothesis (Kessler et al., 2005a), set within the wider “Global Workspace” framework (Dehaene et al., 2003a), which accounts for the dynamic interaction of top-down expectations with bottom-up visual processing. I envisage this novel aspect of expectations complementing the growing knowledge of the AB and emphasising the importance of network dynamics as a metaphor for the parallel distributed processing in the brain.

Dynamic imagery refers both to the imaginary transformation of objects and to the imagination of bodily movements. It is hypothesised that dynamic imagery involves both motoric and visuo-spatial representations and to demonstrate that they operate at the cortical level of the brain, subjects' electroencephalograms (EEG) were recorded whilst they performed a variety of dynamic imagery tasks. It was further hypothesised that cortical activity recorded during these tasks would vary as a function of individual differences in imagery ability. Due to the lack of consensus on the validity both of 'objective' and 'subjective' measures of imagery ability, both kinds of instrument were used in this thesis. It was hoped that the EEG would provide objective evidence of the validity of these measures. During imaginary transformation there was an increase in cortical activation over prefrontal and parieto-occipital cortex, suggesting that high-level motoric and visuo-spatial representations are active during this task. No difference was observed in the EEG of subjects classified according to subjective report but differences were observed when they were classified according to task performance. During movement imagery, an increase in activation over the pre-frontal and parietooccipital cortex was observed, supporting the involvement of motoric and visuo-spatial representations. However, significant results were only obtained when the experimental task imposed sufficiently high cognitive demands on subjects. Only objective measures of imagery ability were correlated to imagery related changes in cortical activity. These studies demonstrate the difficulty of modifying behavioural tasks to suit the restrictions of the psychophysiological environment. It is suggested that while having some benefit, the EEG presents major difficulties to the investigation of dynamic imagery. Given the restrictions of the experimental environment only simple movements are possible, thereby limiting the scope of experimental design.

This portfolio consists of six peer reviewed journal articles relating to the overall theme of the role of decision-making in informing pacing in competitive endurance events. In addition to identifying the importance of pacing decisions in determining performance level achieved, the complexity of the factors informing the process are explored. Whilst physiological state, psychological state, and the perception of exertion are important in a laboratory time trial environment, mass start races are complicated by the presence of other competitors who appear to also influence decision-making. The outputs in this portfolio investigate the role of physiological and psychological parameters in influencing pacing, and present models that may explain the decision-making process leading to observed pacing behaviours. Specifically, work in this portfolio identifies a potential role for affect and the importance of assessment of risk in informing decisions, and proposes that the decision-making process may also be influenced by a hardwired tendency to engage in collective behaviours that could ultimately be detrimental in some endurance sport competitions. It is concluded that pacing behaviour results from complex decision-making processes informed by multiple interconnected physiological and psychological variables, in addition to athlete-environment interactions. Future research priorities are identified as identification of the relative weightings assigned to internal and external (environmental) factors in informing pacing decisions, further development of interdisciplinary models of pacing during competition, and development and testing of interventions that better enable athletes to maintain individually optimal pacing strategies during competition in order to realise performance potential.

The social landscape is filled with an intricate web of species-specific desired objects and course of actions. Humans are highly social animals and, as they navigate this landscape, they need to produce adapted decision-making behaviour. Traditionally social and non-social neural mechanisms affecting choice have been investigated using different approaches. Recently, in an effort to unite these findings, two main theories have been proposed to explain how the brain might encode social and non-social motivational decision-making: the extended common currency and the social valuation specific schema (Ruff & Fehr 2014). One way to test these theories is to directly compare neural activity related to social and non-social decision outcomes within the same experimental setting. Here we address this issue by focusing on the neural substrates of social and non-social forms of uncertainty. Using functional magnetic resonance imaging (fMRI) we directly compared the neural representations of reward and risk prediction and errors (RePE and RiPE) in social and non- social situations using gambling games. We used a trust betting game to vary uncertainty along a social dimension (trustworthiness), and a card game (Preuschoff et al. 2006) to vary uncertainty along a non-social dimension (pure risk). The trust game was designed to maintain the same structure of the card game. In a first study, we exposed a divide between subcortical and cortical regions when comparing the way these regions process social and non-social forms of uncertainty during outcome anticipation. Activity in subcortical regions reflected social and non-social RePE, while activity in cortical regions correlated with social RePE and non-social RiPE. The second study focused on outcome delivery and integrated the concept of RiPE in non-social settings with that of fairness and monetary utility maximisation in social settings. In particular these results corroborate recent models of anterior insula function (Singer et al. 2009; Seth 2013), and expose a possible neural mechanism that weights fairness and uncertainty but not monetary utility. The third study focused on functionally defined regions of the early visual cortex (V1) showing how activity in these areas, traditionally considered only visual, might reflect motivational prediction errors in addition to known perceptual prediction mechanisms (den Ouden et al 2012). On the whole, while our results do not support unilaterally one or the other theory modeling the underlying neural dynamics of social and non-social forms of decision making, they provide a working framework where both general mechanisms might coexist.