Search

This thesis draws together a wide range of relevant scientific, medical, and philosophical research and practice, to offer a novel approach to examining the nature of the mind. Methodologically, the thesis uses primarily two key strands of contemporary philosophy, traditional ‘linguistic turn’ analytic philosophy and broadly pragmatist ‘practical turn’ philosophy of science, with a specific focus on bringing these to bear in an interdisciplinary context. This is a fairly widespread methodology in recent philosophy, that aims to synthesise scientific findings, to examine how these might inform or recast debates in philosophy, and to explore how the positions within those philosophical debates might be relevant to the practice of the relevant areas of science and medicine. \ud \ud The thesis centres on a series of five ‘case studies’, each examining a key proposed use for the concepts in science or medicine, in an area where they seem most likely to be used successfully (Chapters 3 to 7). This argument by case studies is contextualized by an examination of the relevant philosophical background, especially topics in analytic philosophy of mind (Chapter 2). \ud \ud By considering these case studies, it is possible to further specify how exactly the concepts are used in science, whether this is helpful, and what the concepts would have to be like to be helpful used in those ways. The thesis argues that the concepts appear to be generally unhelpful, and suggests that the best approach may be to avoid making use of the concepts in favour of replacement concepts better-suited to the relevant contexts. This conclusion is defended against alternatives, drawing primarily on historically- and practice-informed philosophy of science (Chapter 8).

Recently, the discussion regarding the consequences of cutting the corpus callosum (“split-brain”) has regained momentum (Corballis, Corballis, Berlucchi, & Marzi, Brain, 141(6), e46, 2018; Pinto et al., Brain, 140(5), 1231–1237, 2017a; Pinto, Lamme, & de Haan, Brain, 140(11), e68, 2017; Volz & Gazzaniga, Brain, 140(7), 2051–2060, 2017; Volz, Hillyard, Miller, & Gazzaniga, Brain, 141(3), e15, 2018). This collective review paper aims to summarize the empirical common ground, to delineate the different interpretations, and to identify the remaining questions. In short, callosotomy leads to a broad breakdown of functional integration ranging from perception to attention. However, the breakdown is not absolute as several processes, such as action control, seem to remain unified. Disagreement exists about the responsible mechanisms for this remaining unity. The main issue concerns the first-person perspective of a split-brain patient. Does a split-brain harbor a split consciousness or is consciousness unified? The current consensus is that the body of evidence is insufficient to answer this question, and different suggestions are made with respect to how future studies might address this paucity. In addition, it is suggested that the answers might not be a simple yes or no but that intermediate conceptualizations need to be considered.

Researchers often adjudicate between models of memory according to the models’ ability to explain impaired patterns of performance (e.g., in amnesia). In contrast, evidence from special groups with enhanced memory is very rarely considered. Here, we explored how people with unusual perceptual experiences (synaesthesia) perform on various measures of memory and test how computational models of memory may account for their enhanced performance. We contrasted direct and indirect measures of memory (i.e., recognition memory, repetition priming, and fluency) in grapheme–colour synaesthetes and controls using a continuous identification with recognition (CID-R) paradigm. Synaesthetes outperformed controls on recognition memory and showed a different reaction-time pattern for identification. The data were most parsimoniously accounted for by a single-system computational model of the relationship between recognition and identification. Overall, the findings speak in favour of enhanced processing as an explanation for the memory advantage in synaesthesia. In general, our results show how synaesthesia can be used as an effective tool to study how individual differences in perception affect cognitive functions.

The brain generates predictions about the world based on our prior experiences. Such phenomena have been formally quantified through the framework of Bayesian perceptual inference. The popularity of the Bayesian framework as a theory of perception has increased greatly over the years, but there are still many questions that need to be addressed before we can ascertain whether perception can be classified as truly Bayesian. In this thesis, I investigate whether time perception follows the principles of Bayesian models of perception. The main questions I focused on are how the variability of prior expectations and individual differences in the ability to perceive durations accurately influence temporal estimation. Bayesian models suggest that the magnitude of biases towards the prior would increase if the variance of the prior decreases, but to date, this prediction has not been adequately investigated. Similarly, the theory also suggests that sensory precision, observer’s ability to detect small changes in stimulus magnitude, should also affect perceptual biases, with greater sensory precision resulting in a weaker bias towards the prior. In addition, I was also interested in investigating what brain processes give rise to the perceptual biases that observers experience in magnitude estimation tasks. To do this, across different experiments, I used EEG to investigate if the brain tracks observers’ subjective experience of duration, and eye-tracking to investigate the previously proposed role of dopamine in biasing duration estimation. Finally, I also investigated to what extent prior expectations and time perception, in general, are influenced by conscious awareness. Overall, the experiments presented in this thesis aim to further our understanding of how the brain constructs our perception of time and whether Bayesian frameworks constitute a useful tool for understanding perception in general.

To investigate how embodied sensorimotor interactions shape subjective visual experience, we developed a novel combination of Virtual Reality (VR) and Augmented Reality (AR) within an adapted breaking continuous flash suppression (bCFS) paradigm. In a first experiment, participants manipulated novel virtual 3D objects, viewed through a head-mounted display, using three interlocking cogs. This setup allowed us to manipulate the sensorimotor contingencies governing interactions with virtual objects, while characterising the effects on subjective visual experience by measuring breakthrough times from bCFS. We contrasted the effects of the congruency (veridical versus reversed sensorimotor coupling) and contingency (live versus replayed interactions) using a motion discrimination task. The results showed that the contingency but not congruency of sensorimotor coupling affected breakthrough times, with live interactions displaying faster breakthrough times. In a second experiment, we investigated how the contingency of sensorimotor interactions affected object category discrimination within a more naturalistic setting, using a motion tracker that allowed object interactions with increased degrees of freedom. We again found that breakthrough times were faster for live compared to replayed interactions (contingency effect). Together, these data demonstrate that bCFS breakthrough times for unfamiliar 3D virtual objects are modulated by the contingency of the dynamic causal coupling between actions and their visual consequences, in line with theories of perception that emphasise the influence of sensorimotor contingencies on visual experience. The combination of VR/AR and motion tracking technologies with bCFS provides a novel methodology extending the use of binocular suppression paradigms into more dynamic and realistic sensorimotor environments.

Recent years have seen an increasing theoretical and empirical appreciation of bodily influences on adaptive processes. The body and action are proposed to play a central part in our interactions with the world through motivating behaviours, colouring perception with emotion, and shaping conscious experience. Instrumental learning is a fundamental substrate of adaptive behaviour, and can be used as a vehicle to understand the relationships between those processes. This work investigates the impact of bodily information and the need for conscious access in instrumental learning, as well as whether instrumentally learned, active associations shape conscious experience.\ud \ud Chapters 2 and 3 ask whether cardiac information affects simple forms of adaptive behaviour, such as unconscious instrumental conditioning. The results show evidence for absence of unconscious learning, in contrast to previous reports, and absence of any learning-related cardiac activity without stimulus awareness. Together, those chapters show that instrumental conditioning may require conscious awareness. Chapters 4 and 5 further investigate the feasibility of unconscious instrumental learning. Chapter 4 is a Stage 1 Registered Replication of a prominent paradigm demonstrating unconscious instrumental learning, leveraging statistical and methodological advances. Chapter 5 constitutes a conceptual replication of the same paradigm in two modes of conditioning – trace and delay – demonstrating absence of successful instrumental conditioning without conscious awareness. Chapter 6 shifts focus from the body on the inside to the body on the outside, using instrumental learning to examine the effect of action on our conscious experience. The results demonstrate that access to consciousness is facilitated by our instrumental actions in the world. \ud \ud Overall, this body of work extends the current understanding of instrumental learning as a fundamental component of adaptive behaviour, showing that conscious access is required to drive adaptive interactions with the world, and to further shape our conscious perception in line with action.

Metacognitive theories of hypnotic responding, such as the cold-control theory, assert that people engage in strategies to create the experience requested by a suggestion (e.g., percept of something that is not present). This act is accompanied with the feeling of involuntariness due to a disrupted metacognition that makes suggestible people (highs) unaware of their intention to be engaged in the strategy. The presented research investigated predictions drawn from the cold-control theory focusing on the claim that hypnotic suggestions should not provide highs with any special abilities, since hypnotic responses are implemented by traditional cognitive control processes. In several experiments, the word-blindness suggestion (suggestion to see meaningless words in the Stroop task) was applied. The suggestion halves the extent of the Stroop interference when it is given to highs, posing a challenge to the metacognitive account of hypnosis and so providing a unique opportunity to test its assumptions. In addition, as the experimental usage of hypnosis requires offline screening to identify potential participants, I investigated whether it is possible to conduct the screening online to ease the costs of recruitment. Throughout this thesis, the Bayes factor was applied for hypothesis-testing. In the last chapter, a case with a 2x2 design (a design that was frequently used in this thesis) is presented to demonstrate how Bayes factors with cut-offs of good enough evidence relate to the old inferential mistake of the neglect of the test of interaction.\ud \ud This thesis presents empirical evidence that responses to the word-blindness suggestion are not produced by the disruption of reading. First, the extent of the effect is influenced by the proportion of incongruent Stroop trials of the experimental blocks implying that the suggestion alleviates response competition whereas it does not de-automatise reading. Second, when highs are asked to use simple visual strategies, such as blurring and looking-away, to reduce the Stroop interference, the pattern of results produced by the strategies are not in harmony with those of the word-blindness suggestion deeming it unlikely that highs use these strategies when they respond to the suggestion. This thesis also examines whether a voluntary act to imagine meaningless words is sufficient to reduce the Stroop interference. Consistent with the core idea of cold control theory, we found a positive correlation between the extent to which highs reduced interference in the volitional request and in the suggestion conditions. Nonetheless, the current strength of evidence is not good enough to conclude whether or not voluntary and hypnotic responses can reduce the interference to the same extent. The experiment comparing offline and online hypnotic screening demonstrated evidence supporting the notion that hypnotic suggestibility (measured via the SWASH) can be assessed online. Finally, different scenarios of a case study were presented to help researchers develop the right intuition on the issue of why Bayesian evidence for H1 in one group and Bayesian evidence for H0 in another group does not mean Bayesian evidence for the difference between the two by itself.

Several prominent theories claim that humans possess specialised socio-cognitive skills that emerge early in ontogeny and are attributable to selective histories not shared by other hominids. The generally poor performance of nonhuman primates on tasks designed to measure skills of joint attention, such as the Object Choice Task (OCT), is a key evidence base for these theories. Similar claims are made for domestic dogs, whose apparent proficiency in following pointing cues is taken as evidence for the idea that domestication selected for advanced socio-cognitive skills. The aim of this thesis is to extend current reviews which highlight methodological differences in OCT studies that compare across species, by first analysing the prevalence and the effects of such confounds in the existing literature, and then by conducting a series of systematic experiments to further investigate how these differences may affect behavioural responses. This thesis presents six papers, beginning with a meta-analysis of 71 published OCT studies with nonhuman primates and dogs, which finds between-groups differences in subjects’ pre-experimental histories, the use of a barrier in the form of a test cage, and the types of cues presented. Effects of performance associated with these differences were also found. Following this are four papers which present the results of empirical studies manipulating the presence of a barrier in the testing environment and the spatial configuration of the test set-up distinguishing between central and peripheral versions of the task with human children and dogs. For both taxonomic groups, there were differences in the behavioural responses elicited, and some performance effects for dogs. A further paper finds no effect of manipulating food reward type in an OCT with children. This demonstrates that failing to match testing environments represents an experimental confound and challenges the validity of phylogenetic theories based on studies which use incommensurate test protocols.

Taking risks is part of everyday life. Some people actively pursue risky activities (e.g., jumping out of a plane), while others avoid any risk (e.g., people with anxiety disorders). Paradoxically, risk-taking is a primitive behaviour that may lead to a happier life by offering a sense of excitement through self-actualization. Here, we demonstrate for the first time that sour - amongst the five basic tastes (sweet, bitter, sour, salty, and umami) - promotes risk-taking. Based on a series of three experiments, we show that sour has the potential to modulate risk-taking behaviour across two countries (UK and Vietnam), across individual differences in risk-taking personality and styles of thinking (analytic versus intuitive). Modulating risk-taking can improve everyday life for a wide range of people.

Granger causality is well established within the neurosciences for inference of directed functional connectivity from neurophysiological data. These data usually consist of time series which subsample a continuous-time biophysiological process. While it is well-known that subsampling can lead to imputation of spurious causal connections where none exist, here we address the equally important issue of the effects of subsampling on the ability to reliably detect causal connections which do exist. Neurophysiological processes typically feature signal propagation delays on multiple time scales; accordingly, we base our analysis on a distributed-lag, continuous-time stochastic model, and consider Granger causality in continuous time at finite prediction horizons. Via exact analytical solutions, we identify relationships among sampling frequency, underlying causal time scales and detectability of causalities. Our analysis reveals complex interactions between the time scale(s) of neural signal propagation and sampling frequency: we demonstrate that Granger causality decays exponentially as the sample time interval increases beyond causal delay times, identify detectability "black spots" and "sweet spots", and show that subsampling may sometimes improve detectability. We also demonstrate that the invariance of Granger causality under causal, invertible filtering fails at finite prediction horizons. We discuss the implications of our results for inference of Granger causality at the neural level from various neurophysiological recording modes, and emphasise that sampling rates for causal analysis of neurophysiological time series should be informed by domain-specific time scales., Comment: In review, Journal of Neuroscience Methods

Time perception is a core aspect of human experience, yet the precise cognitive and neural mechanisms underlying it remain unknown. A prominent account is the pacemaker-accumulator model, in which regular ticks of some physiological or neural pacemaker are accumulated and read out as time. A neural substrate for this putative system has been suggested in dopaminergic mid-brain neurons, based on studies indicating that perceptual decisions about time vary with striatal dopamine level, such as following spontaneous blinks. Alternatively, broad physiological processes such as heartbeat have been proposed as pacemaker, as time perception can be modulated by physiological arousal. However, both accounts have difficulty accounting for the intuitive and repeatedly observed finding that time perception varies depending on the content of perceptual experience. Here, we examine evidence for physiological influences on time perception in a large dataset of human duration estimates for naturalistic videos between 1-64 seconds. The content of the videos varied widely, with some depicting walking around a city or countryside, while others depicted more stationary scenes in an office or café. While participants viewed the videos, we recorded their cardiac and eye activity. Participants’ duration estimates were biased according to scene content - rapidly changing city scenes were estimated as longest, more stationary scenes the shortest. Contrary to previous claims, heart rate, pupil size, and blinking were not related to duration estimates. We interpret these results in terms of a recent proposal that tracking change in perceptual classification networks provides a suitable basis for human time perception, indicating that previous assertions of the importance of physiological factors in human time perception should be tempered.

Representation remains ubiquitous in scientific explanations of cognition. At the same \ud time, philosophers continue to question what, if anything, representation contributes to \ud cognitive science. Whilst some practically define cognition in terms of operations \ud performed over representations, others take the very concept of subpersonal \ud representation to be incoherent. Despite the longstanding debate, this thesis argues that \ud we now possess the resources needed to provide a satisfactory account of cognitive \ud representation, taking the challenges raised by eliminativists as an opportunity to refine \ud our understanding of its explanatory role. \ud \ud I defend a ‘mechanistic approach’ that presents representational explanations as a kind of \ud mechanistic explanation. This approach has three main parts which pull together several \ud promising threads in the literature to form an original account. The first part is a \ud mechanistic interpretation of explanations in cognitive science. This interpretation \ud provides insight into the sort of explanans cognitive science offers, and the sort of \ud theoretical entity a cognitive representation might be. The second part is acceptance of \ud the increasingly popular notion of ‘structural’, ‘simulation’ or ‘surrogate representation’ \ud (‘S-representation’). This notion provides an empirically plausible and well-defined set \ud of functional criteria for a genuinely representational mechanism, drawing an \ud illuminating analogy between the functional role of a possible cognitive mechanism and \ud a type of ordinary representation. The third part is a ‘mechanistic account of content’. \ud This provides a naturalistically respectable foundation for representation’s paradigmatic \ud semantic properties at the subpersonal level. Overall, the mechanistic approach ensures \ud that representation ascriptions play a robust role anchored in our dominant explanatory \ud framework. From this perspective, the future of cognitive representation looks bright.

The application of Bayesian techniques to the study and computational modelling of biological systems is one of the most remarkable advances in the natural and cognitive sciences over the last 50 years. More recently, it has been proposed that Bayesian frameworks are not only useful for building descriptive models of biological functions, but that living systems themselves can be seen as Bayesian (inference) machines. On this view, the statistical tools more traditionally used to account for data in biology, neuroscience and psychology, are now used to model the mechanisms underlying functions and properties of living systems as if the systems themselves were the ones“calculating”those probabilities following Bayesian inference schemes. The free energy principle (FEP) is a framework proposed in light of this paradigm shift, advocating the minimisation of variational free energy, a proxy for sensory surprisal, as a general computational principle for biological systems. More intuitively and under some simplifying assumptions,the minimisation of variational free energy reduces,for an agent,to the minimisation of prediction errors on sensory input. Initially proposed as a candidate unifying theory of brain functioning, the FEP was later extended to encompass hypotheses on the origins of life, and is nowadays discussed in the cognitive science community for its possible implications for theories of the mind. In particular,one of the most popular process theories derived from the FEP,active inference,describes a biologically plausible algorithmic implementation of this principle with several repercussions on our understanding of cognition. In this thesis, I will focus on the role of this process theory for action and perception. In active inference, the two of them are combined in a closed sensorimotor loopasco-dependent processes of minimisation of a single loss function,variational free energy, with respect to different sets of variables. Building on this, I will suggest that some of the core ideas of active inference are best seen in terms of enactive, embodied, extended and embedded (4E) theories, in contrast to the majority of the literature emphasising its apparent connections to more traditional, computational, accounts of the mind. In particular, I will develop this argument by focusing on some proposals central to 4E approaches: (a) the non-brain-centric nature of cognitive processes,(b)the lack of explicit representations of the world,(c)the coupling of agent-environment systems and (d) the necessity of real-time feedback signals from the environment. Under the FEP formulation, I will present a series of case studies with mainly two objectives in mind: 1) to conceptually analyse and reframe these 4E ideas in the context of active inference, arguing for the advantages of their formalisation in a more general probabilistic (Bayesian) framework and, 2) to present new mathematical models and agent-based implementations of some of the conceptual connections between Bayesian inference frameworks and 4E proposals, largely missing in the literature.

Neuroimaging studies of the psychedelic state offer a unique window onto the neural basis of conscious perception and selfhood. Despite well understood pharmacological mechanisms of action, the large-scale changes in neural dynamics induced by psychedelic compounds remain poorly understood. Using source-localised, steady-state MEG recordings, we describe changes in functional connectivity following the controlled administration of LSD, psilocybin and low-dose ketamine, as well as, for comparison, the (non-psychedelic) anticonvulsant drug tiagabine. We compare both undirected and directed measures of functional connectivity between placebo and drug conditions. We observe a general decrease in directed functional connectivity for all three psychedelics, as measured by Granger causality, throughout the brain. These data support the view that the psychedelic state involves a breakdown in patterns of functional organisation or information flow in the brain. In the case of LSD, the decrease in directed functional connectivity is coupled with an increase in undirected functional connectivity, which we measure using correlation and coherence. This surprising opposite movement of directed and undirected measures is of more general interest for functional connectivity analyses, which we interpret using analytical modelling. Overall, our results uncover the neural dynamics of information flow in the psychedelic state, and highlight the importance of comparing multiple measures of functional connectivity when analysing time-resolved neuroimaging data.

My project is an empirically informed investigation of the philosophical problem of mental causation, and simultaneously a philosophical investigation of the status of cognitive scientific generalisations. If there is such a thing as mental causation, that is, mental states having effects qua mental states, and if we can classify the mental states involved in these causes in a way useful for making predictions and giving scientific explanations, then these states will be natural kinds. The first task, then, is to show that there is an account of natural kindhood that can accommodate cognitive kinds. The second task is to say how the scientific statements made using these mental kinds are not susceptible to being reduced to statements about physical kinds, and in fact require taking into account facts at many levels of explanation, including the biological and social levels. Lastly, the case will be made for Virtual Machine Functionalism being the correct account of the relationship between cognitive states and the broader physical world. I will claim that although there may be problems with traditional accounts of natural kinds and mental representations when it comes to contemporary cognitive science, this is no reason for thinking that those terms are not useful; we should refine rather than eliminate them. Something would be lost in our understanding if we rejected these terms and the theoretical understanding they contain, something that was present before some mistaken theoretical details came to be associated with the terms. Perhaps some terms that have been coined in the development of our understanding of the mind, such as ‘qualia,’ should be dispensed with, but others just need to be cleaned up. Broadly speaking, my argument will be that squaring the widely held but somewhat contradictory intuitions of physicalism and anti-reductionism regarding mental states will require modification of two other commonly held intuitions, namely physical causal closure and supervenience. Another way of stating my aim is in terms of defending the intuitive distinction between metaphorical and literal uses of intentional vocabulary, such as ‘wanting’ and ‘trying,’ against those who question the meaningfulness of this distinction because they take a physicalist stance on questions of consciousness. They may say the distinction is merely verbal, that there is no real difference between saying of a raindrop that it is ‘trying’ to get to the bottom of the window pane, and saying of a person that he or she is trying to get to the top of the mountain. Much of what follows is an attempt to describe a metaphysics that is materialist and scientific, but in which the difference between the two cases has a natural place. 4 The difference lies in the idea of intentionality: in the case of my desiring something, there is a mental state ‘in’ me that is there because it has the function of directing my actions towards bringing about the desired state of affairs. Such states are things that can be scientifically studied, and a scientific account of human action would be incomplete if it did not refer to such states. In the case of the water drop, there are no similar states without which the scientific understanding of water droplet action would be incomplete. The temptation to elide the distinction between intentional and non-intentional descriptions is based on a belief that since all causation is physical, there is no meaningful distinction between the kinds of causes that makes water drops drop, and those that make climbers climb. This results from the fact that it is sometimes felt that reference to such things as personal agency in intentional explanations of action is to allow in a disagreeable form of dualism. I will argue that a complete, physicalistic, scientific account of human behaviour must include reference to irreducible, mental kinds, such as beliefs and desires. The form of the argument follows the content, with natural kinds at the centre of the web of concepts that form our understanding of mind and its place in the natural world. The starting point is simple folk explanations of human actions, like, ‘He ate the apple because…’ followed by a set of conditions including combinations of beliefs and desires that together constitute sufficient reasons for eating the apple. Many would say such purported explanations are fictions that mask our ignorance of the true story, which will, when we know how to tell it, have a reduced cast of characters, an exclusive set of ‘purely’ physical types. This is well-trodden ground, onto which defenders of ‘embodied cognitive science’ have stepped. However, it is not clear who they will side with, whether they could tip the balance one way or the other, or indeed whether they will even be a unified force. A ‘topographical’ account of natural kinds will be developed that avoids problems other accounts face, and which is suitable for use in the general statements constructed in embodied cognitive science. Following that, we will use this account in the debate around the autonomy of special sciences in general, and the problem of mental causation in particular. The discussion will then broaden out into an investigation of causation, including a refined understanding of physical causal closure. After applying the results of these discussions to our understanding of the supervenience relation, a defensible account of emergentism will be given. Next, we will look at the kinds of properties of mental states that may be referred to in explanations of rational action, namely, the ¬representational contents of mental states. In order to understand the nature of these states, the feedback dynamics between hierarchically structured levels of cognition involved in their evolution will be foregrounded, leading to a picture of embodied cognition that is broad and externalist. We will then look at experiential 5 properties, showing them to be an inseparable part of intentional states, and describing how subjecthood is emergent from brain/body/world dynamics. We will finish by outlining the implications of the refined functionalist account defended for the metaphysical notions we started with. The conclusion drawn will be that we can indeed refer to genuine mental causes which ground the non-metaphorical use of intentional explanations. Finally, I will sketch some implications for the idea of free will using empirical landmarks from cognitive science to find a path through the eroded philosophical landscape, while at the same time using these old philosophical waymarkers to guide the scientific exploration of cognition ahead of us.

Scientific research on consciousness is critical to multiple scientific, clinical, and ethical issues. The growth of the field could also be beneficial to several areas including neurology and mental health research. To achieve this goal, we need to set funding priorities carefully and address problems such as job creation and potential media misrepresentation., SCOPUS: no.j, info:eu-repo/semantics/published

Addiction is characterised by maladaptive drug-approach behaviours, some of which may take place without conscious cognitive control. Through repeated associations with a substance, drug related stimuli acquire incentive salience properties via Pavlovian reward learning, triggering these responses. \ud In order to better understand implicit processes in addiction it is crucial to increase our knowledge about unconscious reward mechanisms. Previous literature has failed to thoroughly demonstrate the ability of Pavlovian conditioned stimuli to generate responses in the absence of stimulus-outcome contingency awareness. Therefore, an effort was put to develop novel techniques measuring different aspects of conditioning. \ud Using an Emotional Attentional Blink, we proved stimuli associated with high probabilities of reward (HR) generated increased attentional responses in participants Unaware of contingencies. Integrating Conditioned Stimuli (CS) as task-irrelevant distractors in a Flanker task we found HR stimuli interfered with cognitive control, again implicitly. A novel methodology, based on Bayesian analyses, allowed us determining the unconscious nature of learning, strengthening our findings. Conversely, subjective hedonic responses were not modulated by implicit learning, highlighting the inadequacy of such measures for the study of implicit conditioning. \ud In order to further understand individual differences in the development of conditioned responses, we examined the role of interoception, the mental representation of internal bodily sensations, in this matter. It was shown that interoceptive awareness modulates the development of reward prediction and hedonic responses in Pavlovian conditioning. We also examined the effect of a natural reward, alcohol, on interoceptive awareness, and found that under acute alcohol administration interoceptive awareness facilitates the perception of subjective substance effects. \ud These findings have important implications for our understanding of basic addictive processes. The ability of implicit CS to generate responses supports the existence of drug-approach behaviours devoid of conscious awareness. The role of interoception in Pavlovian conditioning provides the basis for its integration in classic learning theories.

According to the Integrated Information Theory of Consciousness, consciousness is a fundamental observer-independent property of physical systems, and the measure Phi of integrated information is identical to the quantity or level of consciousness. For this to be plausible, there should be no alternative formulae for Phi consistent with the axioms of IIT, and there should not be cases of Phi being ill-defined. This article presents three ways in which Phi, in its current formulation, fails to meet these standards, and discusses how this problem might be addressed., Comment: 8 pages

The metacognitive ability to introspect about self-performance varies substantially across individuals. Given that effective monitoring of performance is deemed important for effective behavioural control, intervening to improve metacognition may have widespread benefits, for example in educational and clinical settings. However, it is unknown whether and how metacognition can be systematically improved through training independently of task performance, or whether metacognitive improvements generalize across different task domains. Across 8 sessions, here we provided feedback to two groups of participants in a perceptual discrimination task: an experimental group (N = 29) received feedback on their metacognitive judgments, while an active control group (N = 32) received feedback on their decision performance only. Relative to the control group, adaptive training led to increases in metacognitive calibration (as assessed by Brier scores) which generalized both to untrained stimuli and an untrained task (recognition memory). Leveraging signal detection modeling we found that metacognitive improvements were driven both by changes in metacognitive efficiency (meta-d’/d’) and confidence level, and that later increases in metacognitive efficiency were positively mediated by earlier shifts in confidence. Our results reveal a striking malleability of introspection and indicate the potential for a domain-general enhancement of metacognitive abilities.

In grapheme-colour synaesthesia (GCS), the presentation of letters or numbers induces an additional ‘concurrent’ experience of colour. Early functional MRI (fMRI) investigations of GCS reported activation in colour-selective area V4 during the concurrent experience. However, others have failed to replicate this key finding. We reasoned that individual differences in synaesthetic phenomenology might explain this inconsistency in the literature. To test this hypothesis, we examined fMRI BOLD responses in a group of grapheme-colour synaesthetes (n=20) and matched controls (n=20) while characterising the individual phenomenology of the synaesthetes along dimensions of ‘automaticity’ and ‘localisation’. We used an independent functional localiser to identify colour-selective areas in both groups. Activations in these areas were then assessed during achromatic synaesthesia-inducing, and non-inducing conditions; we also explored whole brain activations, where we sought to replicate the existing literature regarding synaesthesia effects. Controls showed no significant activations in the contrast of inducing > non-inducing synaesthetic stimuli, in colour-selective ROIs or at the whole brain level. In the synaesthete group, we correlated activation within colour-selective ROIs with individual differences in phenomenology using the Coloured Letters and Numbers (CLaN) questionnaire which measures, amongst other attributes, the subjective automaticity/attention in synaesthetic concurrents, and their spatial localisation. Supporting our hypothesis, we found significant correlations between individual measures of synaesthetic phenomenology and BOLD responses in colour-selective areas, when contrasting inducing against non-inducing stimuli. Specifically, left-hemisphere colour area responses were stronger for synaesthetes scoring high on phenomenological localisation and automaticity/attention, while right-hemisphere colour area responses showed a relationship with localisation only. In exploratory whole brain analyses, the BOLD response within several other areas was also correlated with these phenomenological factors, including the intra-parietal sulcus, insula, precentral and supplementary motor areas. Our findings reveal a network of regions underlying synaesthetic phenomenology and they help reconcile the diversity of previous results regarding colour-selective BOLD responses during synaesthesia, by establishing a bridge between neural responses and individual synaesthetic phenomenology.

Integrated Information Theory (IIT) is a prominent theory of consciousness that has at its centre measures that quantify the extent to which a system generates more information than the sum of its parts. While several candidate measures of integrated information (&ldquo, &Phi, &rdquo, ) now exist, little is known about how they compare, especially in terms of their behaviour on non-trivial network models. In this article, we provide clear and intuitive descriptions of six distinct candidate measures. We then explore the properties of each of these measures in simulation on networks consisting of eight interacting nodes, animated with Gaussian linear autoregressive dynamics. We find a striking diversity in the behaviour of these measures&mdash, no two measures show consistent agreement across all analyses. A subset of the measures appears to reflect some form of dynamical complexity, in the sense of simultaneous segregation and integration between system components. Our results help guide the operationalisation of IIT and advance the development of measures of integrated information and dynamical complexity that may have more general applicability.

Synesthesia is associated with additional perceptual experiences, which are automatically and consistently triggered by specific inducing stimuli. Synesthesia is also accompanied by more general sensory and cortical changes, including enhanced modality-specific cortical excitability. Extensive cognitive training has been shown to generate synesthesia-like phenomenology but whether these experiences are accompanied by neurophysiological changes characteristic of synesthesia remains unknown. Addressing this question provides a unique opportunity to elucidate the neural basis of perceptual plasticity relevant to conscious experiences. Here we investigate whether extensive training of letter-color associations leads not only to synesthetic experiences, but also to changes in cortical excitability. We confirm that overtraining synesthetic associations results in synesthetic phenomenology. Stroop tasks further reveal synesthesia-like performance following training. Electroencephalography and transcranial magnetic stimulation show, respectively, enhanced visual evoked potentials (in response to untrained patterns) and lower phosphene thresholds, demonstrating specific cortical changes. An active (using letter-symbol training) and a passive control confirmed these results were due to letter-color training and not simply to repeated testing. Summarizing, we demonstrate specific cortical changes, following training-induced acquisition of synesthetic phenomenology that are characteristic of genuine synesthesia. Collectively, our data reveal dramatic plasticity in human visual perception, expressed through a coordinated set of behavioral, neurophysiological, and phenomenological changes., This work was supported by the Dr. Mortimer and Theresa Sackler Foundation, which supports the Sackler Centre for Consciousness Science, by the Swiss National Science Foundation (Grant Number PZ00P1_154954), which supports Nicolas Rothen, and by the Daphne Jackson Trust and the Biotechnology and Biological Sciences Research Council (BBSRC), which supports Daniel Bor.

Despite being a fundamental dimension of experience, how the human brain generates the perception of time remains unknown. Here, we provide a novel explanation for how human time perception might be accomplished, based on non-temporal perceptual classification processes. To demonstrate this proposal, we build an artificial neural system centred on a feed-forward image classification network, functionally similar to human visual processing. In this system, input videos of natural scenes drive changes in network activation, and accumulation of salient changes in activation are used to estimate duration. Estimates produced by this system match human reports made about the same videos, replicating key qualitative biases, including differentiating between scenes of walking around a busy city or sitting in a cafe or office. Our approach provides a working model of duration perception from stimulus to estimation and presents a new direction for examining the foundations of this central aspect of human experience., How the brain tracks the passage of time remains unclear. Here, the authors show that tracking activation changes in a neural network trained to recognize objects (similar to the human visual system) produces estimates of duration that are subject to human-like biases.

The mind and brain sciences began with consciousness as a central concern. But for much of the 20th century, ideological and methodological concerns relegated its empirical study to the margins. Since the 1990s, studying consciousness has regained a legitimacy and momentum befitting its status as the primary feature of our mental lives. Nowadays, consciousness science encompasses a rich interdisciplinary mixture drawing together philosophical, theoretical, computational, experimental, and clinical perspectives, with neuroscience its central discipline. Researchers have learned a great deal about the neural mechanisms underlying global states of consciousness, distinctions between conscious and unconscious perception, and self-consciousness. Further progress will depend on specifying closer explanatory mappings between (first-person subjective) phenomenological descriptions and (third-person objective) descriptions of (embodied and embedded) neuronal mechanisms. Such progress will help reframe our understanding of our place in nature and accelerate clinical approaches to a wide range of psychiatric and neurological disorders.

The sense of agency is the experience of being the initiator of our intentional actions and their outcomes. According to higher order thought theory, a representation becomes conscious when there is a higher order state about it. Thus conscious experience, including that of intentions, is metacognitive. The experience of involuntariness characteristic of hypnotic responding may be attributable to the formation and maintenance of inaccurate metacognitive higher order states of intending. Conversely, the practice of Buddhist mindfulness meditation may develop accurate metacognition, including higher order states of intending. Highly hypnotisable people and mindfulness meditators may therefore occupy two ends of a spectrum of metacognitive ability with regard to unconscious intentions. The presented research investigated predicted trait differences in cognitive tasks which directly or indirectly reflect metacognition of intentions: the timing of an experience of an intention to move and the compressed time interval between a voluntary action and its outcome, known as intentional binding. As an implicit measure of sense of agency, intentional binding was also employed to investigate the veridicality of reports of the experience of involuntariness in hypnotic responding. Additionally, while hypnosis presents a unique opportunity to investigate reliable changes in agentic experience, existing hypnosis screening instruments are time consuming and present a barrier to wider adoption of hypnosis as an instrument for studying consciousness. Here a revised, time-efficient hypnosis screening procedure (the SWASH) is presented.\ud Consistent with predictions, highly hypnotisable groups reported later awareness of motor intentions than less hypnotisable groups and meditators earlier awareness than non-meditators. In an intentional binding task, high hypnotisables showed less binding of an action-outcome toward an action (outcome binding) than low hypnotisables and meditators more outcome binding than non-meditators. Outcome binding was reduced in post-hypnotic involuntary action compared to voluntary action. It is proposed that intentional binding is driven by a cue combination mechanism and that these differences reflect varying precision of motor intention related information in reported timing judgements. The SWASH was found to be a reliable hypnosis screening instrument.

Empirical evidence suggests that synesthesia is associated with enhanced sensory processing. A separate body of empirical literature suggests that synesthesia is linked to a specific profile of enhanced episodic and working memory performance. However, whether sensory (iconic) memory performance is also affected by synesthesia remains unknown. Therefore, we tested 22 grapheme-color synesthetes and compared their performance in a partial-report paradigm with 22 individually matched non-synesthete controls. Participants were briefly presented with a circular-letter array and required to report the identity of the letter at a probed target location after various delays. Furthermore, they were required to indicate the subjective clarity of the target letter after every trial. The results suggest that sensory memory performance is enhanced in synesthesia, but only when subjective clarity of the target letter is high. Additional exploratory analyses revealed that synesthetic consistency, which is widely used to confirm the genuineness of synesthesia, correlated significantly with performance in the partial report paradigm. We conclude that synesthesia does not generally enhance sensory memory performance, but that synesthetic experiences may enhance sensory memory performance when perceptual awareness of the target is high. Furthermore, the stability of synesthetic associations may be linked to sensory memory performance.

The greatest genetic factor in how well we age cognitively is Apolipoprotein E (APOE), a single nucleotide polymorphism with three allelic variants: epsilon-2, epsilon-3 and epsilon-4 (hereafter ε2, ε3, ε4). The ε4 allele is associated with an increased risk of cognitive disadvantage in later life, however, the effects of this variant are not isolated to old-age, with some studies reporting cognitive advantages in youth. This thesis investigates the influence of APOE ε4 on cognition from mid-adulthood, a point in the lifespan when the detrimental effects of this allele may be emerging. \ud This thesis begins with a systematic review and meta-analysis of the literature to-date, and suggests attention may be sensitive to ε4 differences in mid-adulthood, however, effects of the allele are not consistently shown, perhaps due to methodological limitations including the use of insensitive neuropsychological batteries (Chapter 1). Next, behavioural paradigms providing a sensitive index of both selective (Chapter 2) and executive attention (Chapter 3), suggest many attentional processes are intact in mid-age (45-55 years) ε4 carriers. Subtle deficits, however, are apparent on prospective memory (PM) and Stroop-switch paradigms, indicating a goal maintenance disadvantage. In addition, a proxy of cognitive reserve was found to moderate the effects of ε4 on executive attention in mid-adulthood (Chapter 4). Follow-up research used paradigms that target the distinct processes supporting focal and non-focal PM to interrogate the profile of change observed in mid-age ε4 carriers, identifying a profile of disadvantage consistent with that observed in pathological ageing (Chapter 5). PM, however, was not found to differentiate ε4 carriers in older individuals at heightened risk of converting to dementia (Chapter 6). Collectively, this research provides evidence for a profile of accelerated ageing in ε4 carriers, with subtle disadvantages apparent in executive attention by the end of the 5th decade.

Altered states of consciousness, such as psychotic or pharmacologically-induced hallucinations, provide a unique opportunity to examine the mechanisms underlying conscious perception. However, the phenomenological properties of these states are difficult to isolate experimentally from other, more general physiological and cognitive effects of psychoactive substances or psychopathological conditions. Thus, simulating phenomenological aspects of altered states in the absence of these other more general effects provides an important experimental tool for consciousness science and psychiatry. Here we describe such a tool, which we call the Hallucination Machine. It comprises a novel combination of two powerful technologies: deep convolutional neural networks (DCNNs) and panoramic videos of natural scenes, viewed immersively through a head-mounted display (panoramic VR). By doing this, we are able to simulate visual hallucinatory experiences in a biologically plausible and ecologically valid way. Two experiments illustrate potential applications of the Hallucination Machine. First, we show that the system induces visual phenomenology qualitatively similar to classical psychedelics. In a second experiment, we find that simulated hallucinations do not evoke the temporal distortion commonly associated with altered states. Overall, the Hallucination Machine offers a valuable new technique for simulating altered phenomenology without directly altering the underlying neurophysiology.

Loss of consciousness can result from a wide range of causes, including natural sleep and pharmacologically induced anesthesia. Important insights might thus come from identifying neuronal mechanisms of loss and re-emergence of consciousness independent of a specific manipulation. Therefore, to seek neuronal signatures of loss of consciousness common to sleep and anesthesia we analyzed spontaneous electrophysiological activity recorded in two experiments. First, electrocorticography (ECoG) acquired from 4 macaque monkeys anesthetized with different anesthetic agents (ketamine, medetomidine, propofol) and, second, stereo-electroencephalography (sEEG) from 10 epilepsy patients in different wake-sleep stages (wakefulness, NREM, REM). Specifically, we investigated co-activation patterns among brain areas, defined as correlations between local amplitudes of gamma-band activity. We found that resting wakefulness was associated with intermediate levels of gamma-band coupling, indicating neither complete dependence, nor full independence among brain regions. In contrast, loss of consciousness during NREM sleep and propofol anesthesia was associated with excessively correlated brain activity, as indicated by a robust increase of number and strength of positive correlations. However, such excessively correlated brain signals were not observed during REM sleep, and were present only to a limited extent during ketamine anesthesia. This might be related to the fact that, despite suppression of behavioral responsiveness, REM sleep and ketamine anesthesia often involve presence of dream-like conscious experiences. We conclude that hyper-correlated gamma-band activity might be a signature of loss of consciousness common across various manipulations and independent of behavioral responsiveness.

To increase fitness for survival, organisms not only passively react to environmental changes but also actively predict future events to prepare for potential hazards within their environment. Accumulating evidence indicates that the human brain is a remarkable predictive machine which constantly models causal relationships and predicts future events. This ‘predictive processing’ framework, a prediction-based form of Bayesian inference, states that the brain continuously generates and updates predictions about incoming sensory signals. This framework has been showing notable explanatory power in understanding the mechanisms behind both human behaviour and neurophysiological data and elegantly specifies the underlying computational principles of the neural system. However, even though predictive processing has the potential to provide a unified theory of the brain (Karl Friston, 2010), we still have a limited understanding about fundamental aspects of this model, such as how it deals with different types of information, learns statistical regularities and perhaps most fundamentally of all what its relationship to conscious experience is. This thesis aims to investigate the major gaps in our current understanding of the predictive processing framework via a series of studies. Study 1 investigated the fundamental relationship between unconscious statistical inference reflected by predictive processing and conscious access. It demonstrated that predictions that are in line with sensory evidence accelerate conscious access. Study 2 investigated how low level information within the sensory hierarchy is dealt with by predictive processing and regularity learning mechanisms through “perceptual echo” in which the cross-correlation between a sequence of randomly fluctuating luminance values and occipital electrophysiological (EEG) signals exhibits a long-lasting periodic (~100ms cycle) reverberation of the input stimulus. This study identified a new form of regularity learning and the results demonstrate that the perceptual echo may reflect an iterative learning process, governed by predictive processing. Study 3 investigated how supra-modal predictive processing is capable of\ud learning regularities of temporal duration and also temporal predictions about future events. This study revealed a supramodal temporal prediction mechanism which processes auditory and visual temporal information and integrates information from the duration and rhythmic structures of events. Together these studies provide a global picture of predictive processing and regularity learning across differing types of predictive information.

Surface diffusion of AMPA receptors, from extra-synaptic to synaptic sites at the plasma membrane, is essential for full long-term potentiation in hippocampal neurons and for fear conditioning in living mice. Learning and memory are thought to rely on the long-term potentiation (LTP) of excitatory synaptic transmission, as a result of either an increase in presynaptic release of the neurotransmitter (glutamate) or recruitment of its postsynaptic receptor (AMPAR) in greater numbers. Now, using molecular techniques for immobilizing AMPARs, Daniel Choquet and colleagues demonstrate that surface diffusion of the receptor, from extra-synaptic to synaptic sites at the plasma membrane, is essential for full LTP in hippocampal neurons, and for fear conditioning in living mice. The results suggest new targets for the deliberate modulation of synaptic plasticity, learning and memory. Long-term potentiation (LTP) of excitatory synaptic transmission has long been considered a cellular correlate for learning and memory1,2. Early LTP (less than 1 h) had initially been explained either by presynaptic increases in glutamate release3,4,5 or by direct modification of postsynaptic AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptor function6,7. Compelling models have more recently proposed that synaptic potentiation can occur by the recruitment of additional postsynaptic AMPA receptors (AMPARs)8, sourced either from an intracellular reserve pool by exocytosis or from nearby extra-synaptic receptors pre-existing on the neuronal surface9,10,11,12. However, the exact mechanism through which synapses can rapidly recruit new AMPARs during early LTP remains unknown. In particular, direct evidence for a pivotal role of AMPAR surface diffusion as a trafficking mechanism in synaptic plasticity is still lacking. Here, using AMPAR immobilization approaches, we show that interfering with AMPAR surface diffusion markedly impairs synaptic potentiation of Schaffer collaterals and commissural inputs to the CA1 area of the mouse hippocampus in cultured slices, acute slices and in vivo. Our data also identify distinct contributions of various AMPAR trafficking routes to the temporal profile of synaptic potentiation. In addition, AMPAR immobilization in vivo in the dorsal hippocampus inhibited fear conditioning, indicating that AMPAR diffusion is important for the early phase of contextual learning. Therefore, our results provide a direct demonstration that the recruitment of new receptors to synapses by surface diffusion is a critical mechanism for the expression of LTP and hippocampal learning. Since AMPAR surface diffusion is dictated by weak Brownian forces that are readily perturbed by protein–protein interactions, we anticipate that this fundamental trafficking mechanism will be a key target for modulating synaptic potentiation and learning.

The world around us is replete with stimuli that unfold over time. When we hear an auditory stream like music or speech or scan a texture with our fingertip, physical features in the stimulus are concatenated in a particular order. This temporal patterning is critical to interpreting the stimulus. To explore the capacity of mice and humans to learn tactile sequences, we developed a task in which subjects had to recognise a continuous modulated noise sequence delivered to whiskers or fingertips, defined by its temporal patterning over hundreds of milliseconds. GO and NO-GO sequences differed only in that the order of their constituent noise modulation segments was temporally scrambled. Both mice and humans efficiently learned tactile sequences. Mouse sequence recognition depended on detecting transitions in noise amplitude; animals could base their decision on the earliest information available. Humans appeared to use additional cues, including the duration of noise modulation segments., This work was supported by the Spanish Ministry of Science and Innovation (grant number BFU2011-23049, co-funded by the European Regional Development Fund; Subprograma Ayudas FPI-MICINN, BES-2012–052293), the Medical Research Council (grant number MR/P006639/1), the Valencia Regional Government (ACOMP2010/199 and PROMETEO/2011/086), and the University of Sussex internal research development fund.

Objectives: Hyperhomocysteinemia in Alzheimer’s disease (AD) is widely reported and appears to worsen as the disease progresses. While active dietary intervention with vitamins B12 and folate decreases homocysteine blood levels, with promising clinical outcomes in Mild Cognitive Impairment (MCI), this so far has not been replicated in established AD populations. The aim of the study is to explore the relationship between hyperhomocystenemia and relevant vitamins as the disease progresses.\ud Methods: In this longitudinal cohort study, 38 participants with mild to moderate AD were followed for an average period of 13 months. Plasma folate, vitamin B12 and homocysteine concentrations were measured at baseline and at follow-up. Dietary intake of B vitamins was also measured. Spearman’s correlations were conducted by homocysteine and B vitamin status.\ud Results: As expected, cognitive status significantly declined over the follow-up period and this was paralleled by a significant increase in homocysteine concentrations (p=0.006). However, during this follow-up period there was no significant decline in neither dietary intake, nor the corresponding blood concentrations of vitamin B12/folate, with both remaining within normal values. Changes in blood concentrations of B vitamins were not associated with changes in homocysteine levels (p>0.05).\ud Conclusion: In this study, the increase in homocysteine observed in AD patients as the disease progresses cannot be solely explained by dietary and blood levels of folate and vitamin B12. Other dietary and non-dietary factors may contribute to hyperhomocysteinemia and its toxic effect in AD, which needs to be explored to optimise timely intervention strategies.

What is the level of consciousness of the psychedelic state? Empirically, measures of neural signal diversity such as entropy and Lempel-Ziv (LZ) complexity score higher for wakeful rest than for states with lower conscious level like propofol-induced anesthesia. Here we compute these measures for spontaneous magnetoencephalographic (MEG) signals from humans during altered states of consciousness induced by three psychedelic substances: psilocybin, ketamine and LSD. For all three, we find reliably higher spontaneous signal diversity, even when controlling for spectral changes. This increase is most pronounced for the single-channel LZ complexity measure, and hence for temporal, as opposed to spatial, signal diversity. We also uncover selective correlations between changes in signal diversity and phenomenological reports of the intensity of psychedelic experience. This is the first time that these measures have been applied to the psychedelic state and, crucially, that they have yielded values exceeding those of normal waking consciousness. These findings suggest that the sustained occurrence of psychedelic phenomenology constitutes an elevated level of consciousness - as measured by neural signal diversity.

In this thesis I develop a novel approach to conscious perception, which I label “radical sensorimotor enactivism” (RSE). In chapter one, I explain how the development of RSE is guided by the tenets of activity and knowledge-how. In chapter two, I outline and explain RSE. Throughout the thesis, I will pit RSE against cognitivist accounts of conscious perception and argue that RSE is to be preferred. \ud \ud In chapters three and four, I highlight two problems facing cognitivist accounts of conscious perception which RSE avoids. I argue that cognitivist accounts of conscious perception face the ‘hard problem of perceptual consciousness’, whilst RSE can provide a phenomenologically plausible deflation of this problem. I next explain why cognitivist accounts are incapable of providing a satisfactory explanation of split-brain syndrome. Then, I argue that RSE can provide a parsimonious explanation of this syndrome. \ud \ud Theories predicated on activity and knowledge-how are often rejected for being incapable of accounting for the brain’s role in conscious perception. In chapter five, I argue that RSE can account for the brain’s role by adopting a non-representational version of predictive processing (PP). Moreover, I argue that the resultant account improves upon cognitivist alternatives. Then, in chapter six, I argue that even representational explanations of PP can be subsumed within RSE by accepting fictionalism about their representational posits. Consequently, I conclude that RSE cannot be objected to for failing to account for the brain’s role in conscious perception. \ud \ud Finally, in chapter seven, I discuss ‘non-veridical’ experiences. Accounts like RSE are often rejected because it is thought they are incapable of explaining the existence of these phenomena. I explain how the existence of such phenomena is wholly compatible with the truth of RSE. Thus, I conclude that RSE should not be rejected solely on the basis that non-veridical experiences exist.

The 'free energy principle' (FEP) has been suggested to provide a unified theory of the brain, integrating data and theory relating to action, perception, and learning. The theory and implementation of the FEP combines insights from Helmholtzian 'perception as inference', machine learning theory, and statistical thermodynamics. Here, we provide a detailed mathematical evaluation of a suggested biologically plausible implementation of the FEP that has been widely used to develop the theory. Our objectives are (i) to describe within a single article the mathematical structure of this implementation of the FEP; (ii) provide a simple but complete agent-based model utilising the FEP; (iii) disclose the assumption structure of this implementation of the FEP to help elucidate its significance for the brain sciences., Comment: 77 pages 2 fugures

Whether perceptual organization favors the simplest or most likely interpretation of a distal stimulus has long been debated. An unbridgeable gulf has seemed to separate these, the Gestalt and Helmholtzian viewpoints. But in recent decades, the proposal that likelihood and simplicity are two sides of the same coin has been gaining ground, to the extent that their equivalence is now widely assumed. What then arises is a desire to know whether the two principles can be reduced to one. Applying Occam’s Razor in this way is particularly desirable given that, as things stand, an account referencing one principle alone cannot be completely satisfactory. The present paper argues that unification of the two principles is possible, and that it can be achieved in terms of an incremental notion of ‘information seeking’ (infotropism). Perceptual processing that is infotropic can be shown to target both simplicity and likelihood. The ability to see perceptual organization as governed by either objective can then be explained in terms of it being an infotropic process. Infotropism can be identified as the principle which underlies, and thus generalizes the principles of likelihood and simplicity.

A growing body of literature shows that the emotional content of verbal material affects reading, wherein emotional words are given processing priority compared to neutral words. Human emotions can be conceptualised within a two-dimensional model comprised of emotional valence and arousal (intensity). These variables are at least in part distinct, but recent studies report interactive effects during implicit emotion processing and relate these to stimulus-evoked approach-withdrawal tendencies. The aim of the present study was to explore how valence and arousal interact at the neural level, during implicit emotion word processing. The emotional attributes of written word stimuli were orthogonally manipulated based on behavioural ratings from a corpus of emotion words. Stimuli were presented during an fMRI experiment while 16 participants performed a lexical decision task, which did not require explicit evaluation of a word′s emotional content. Results showed greater neural activation within right insular cortex in response to stimuli evoking conflicting approach-withdrawal tendencies (i.e., positive high-arousal and negative low-arousal words) compared to stimuli evoking congruent approach vs. withdrawal tendencies (i.e., positive low-arousal and negative high-arousal words). Further, a significant cluster of activation in the left extra-striate cortex was found in response to emotional than neutral words, suggesting enhanced perceptual processing of emotionally salient stimuli. These findings support an interactive two-dimensional approach to the study of emotion word recognition and suggest that the integration of valence and arousal dimensions recruits a brain region associated with interoception, emotional awareness and sympathetic functions., Highlights • Emotional valence and arousal affect reading interactively. • Positive high-arousal and negative low-arousal words evoke conflicting reactions. • Enhanced right insula activation was found in response to conflicting stimuli. • Insula integrates viscero-sensory and cognitive/evaluative information. • Enhanced extra-striate cortex activation was found for emotional than neutral words.

From the editor's introduction: "Ron Chrisley and Aaron Sloman open Part I of this issue with their article “Functionalism, Revisionism, and Qualia.” Chrisley and Sloman discuss revisionism about qualia—the view that tries to navigate between naïve qualia realism and reductive eliminativism. The authors discuss the relevance of their approach to AI. They also relate to the works they view as following the main tenets of revisionism about qualia. This includes Gilbert Harman’s version of functionalism, discussed in much detail (including Harman’s article “Explaining the Explanatory Gap,” published in the spring 2007 issue of this newsletter) and also the psychomotoric approach to qualia by Kevin O’Regan."

Through the evolution of digital media technology, social networks and more recently Web 3.0 (e.g. Cloud-based) technologies, culture and memory is being transformed, both in relation to how memories are represented, and how they may be engaged with or re-accessed.\ud \ud As digital technology alters ways in which knowledge is produced, stored, connected and shared, new terrains, tools and artefacts are formed; new cultural practices alter the ways in which we remember and the ways in which memory is processed, destabilising traditional “historically encoded social habits: religion, authority, morality, traditional values, or political ideology” (Diamantaki 2013).\ud \ud This doctoral project consists of two parts exploring questions of memory in contemporary time.\ud The practice work submitted develops various imaginaries and investigates how to enable mnemonic practices so that works function as memory palaces where bodies and ‘collective’ and ‘networked memories’ (Hoskins, 2010) can be realised.\ud \ud The work, briefly summarised, includes communal activities in public spaces (a series of workshops and heritage day events, Rendezvous, centrally social activities organised between Fabrica and various charitable organisations in Brighton). It includes a series of installation works, as a transitional process of memory between body, object, an investigation of ubiquitous technology, are investigated – iremembr (2009-15); Rendezvous (2010-15); Untitled#21 (2012). And it leads to the development of an installation piece, 200.104.200.2 (2013-15), that seeks to offer or extend the possibilities of the act of remembering, of memory, as a post-Internet experience; a complex temporal, social, spatial and material, overlapping and merging human and silicon memory.\ud \ud In this, the written component of the combined and larger project, questions concerning memory and digital technology, and how to explore them, are taken up in theoretical terms, and the works I have produced returned to and explored in these contexts. A central project here has been to locate new forms of qualities of ‘digital’ memory in a memory map or topology that builds on adapts, and develops other models. Aspects of zones of memory are explored centrally in each of the later thesis chapters each of which also takes up a particular aspect of my practice.\ud \ud The intention – and the contribution to the development of critical thinking around the digital – particularly critical thinking that comes through digital media art practice, is to question how digital technology intervenes in the process of memory; how the concept of digital memory is being thought about; leading me to investigate what does this new digital terrain do as it overlaps and re-writes to some extent the older ones? How does it change ‘how memory happens’.\ud \ud Co-funded by the Arts and Humanities Research Council (AHRC), and the University of Sussex

This thesis identifies, in Nancy’s The Fall of Sleep, a crucial critique of phenomenology. A criticism that demarcates, or limits, phenomenology in declaring: “There is no phenomenology of sleep”. Taking-up this challenge, we consider a number of ways that phenomenologists have, and could, approach sleep. Our thesis, however, does not simply\ud offer possible responses to the problem but also finds, in these answers, important insights into the essence of the charge itself. Sleep and phenomenology are found to be mutually de-limiting – each binds the other, whilst offering foundational insights into its counterpart. Fundamentally, we bring phenomenologies of sleep, as opposed to simply phenomenology, into dialogue with this, Nancean, critique of phenomenology and with Nancy’s account of sleep itself. We describe the distinctly different slumbering interpretations of sleep present, and conspicuously absent, in the work of: Husserl, Heidegger, and Levinas. Part I, after initially elaborating the challenge, presents a direct Husserlian counter, via a recent reconstituting of Husserl’s late notes on sleep. The strengths and weaknesses of this phenomenological investigation sharpens the problem of sleep and leads us to pull back from consciousness-centred accounts. Part II, in contrast, develops our own hypothetical Heideggerian answer. This Part, the longest, uses Heidegger’s existential and comparative analytics to ask ‘Does Dasein sleep?’ This question reveals internal ambiguities of sleep – positioned between existence, life, and death. Part III withdraws from Heideggerian thinking through Levinas’s incisive, and early, interpretation of sleep. This Levinasian retracting opens the possibility of returning to Nancy’s challenge and corresponding description of sleep. Now this radical account is located in relation to, and in communication with, the somnological-phenomenological findings we have awakened in our thesis. The thesis ends by indicating a possible, future, return back from sleep to phenomenology – a dream, still hazy from sleep, of a somnolent phenomenology.

Contemporary models of declarative memory state that when initially learned, all novel information is encoded by the hippocampal system before being consolidated or transformed to depend on neocortical structures subserving semantic memory. Based on observations with functional magnetic resonance imaging (fMRI), this thesis presents evidence that novel associations may be directly encoded by the semantic system in humans. While the hippocampus is often involved in information processing at the early stages of learning, the semantic system is seen to encode associative memory traces in the first instance (chapter 2). Furthermore, it is proposed that the hippocampus is not involved in learning when associative information is gradually accumulated across a series of ambiguous events. This is characteristic of cross-situational learning (xSL) which allows for the acquisition of word-object associations (i.e. nouns) during infancy. It is shown that xSL is not well accounted for by a prominent model of contextual learning - the temporal context model (chapter 3). Additionally, fMRI data suggest that neocortical structures rather than components of the hippocampal system are preferentially involved in xSL compared to traditional methods of training (chapter 4). Finally, it is suggested that rapid hippocampal learning mechanisms rely on specialised neuronal-microglial interactions. The administration of a microglial inhibitor (minocycline) was found to modulate hippocampal function and bias its use when other learning systems would have been more advantageous (chapter 5). Collectively, these findings suggest that the hippocampal system is specialised for rapidly encoding information that is explicitly provided, yet may not be recruited when associative information is collated across ambiguous events. At the same time, the neocortical semantic system may be able to learn new information at faster rates than previously thought. As such, it is hypothesised that amnestic patients may be able to acquire some forms of declarative material if presented in an appropriate manner.

Cognitive process accounts of the advantages conferred by diagrams in problem solving and reasoning have typically attempted to explain an idealised user or a reasoning system that has equivalent to practised knowledge of the task with the target representation. The thesis investigates the question of how diagrams support users in the process of solving unpractised problems in the domain of probability. The research question is addressed by the design and analysis of an empirical study and cognitive model.\ud \ud The main experiment required participants (N=8) to solve a set of unpractised probability problems presented by combined text and diagram. Think-aloud and eye-movement protocols together with given solutions were used to infer the content and process of problem interpretation, solution interpretation and task execution strategies employed by participants. The data suggested that the diagram was used to facilitate problem solving in three different ways by: (a) supporting sub-problem identification, (b) supporting prior knowledge of diagrammatic sub-schemes used for interpreting a solution and (c) supporting the process of interpreting and testing the specific meaning of given problem instructions and self-generated solution instructions.\ud \ud These empirical data were used to develop cognitive models of canonical strategies of the three identified phenomena:\ud \ud • Sub-problem identification advantages are accounted for by proposing that the spatial semantics of diagrams coupled with competences of the visual-spatial processing system and opportunities for demonstrative interpretation strategies increase the probability of goal-relevant data being made available to central cognition for further processing.\ud • Framing advantages are accounted for by proposing that represented diagrammatic sub-schemes (e.g. part-whole portions, icon-arrays, 2D containers etc.) facilitate access to existing prior knowledge used to frame, derive, and reason about information analogically within that scheme.\ud • Advantages in instruction interpretation are related to the specificity of diagrams which support the opportunity to demonstratively test and evaluate the referential meaning of an instruction.\ud \ud The cognitive model also investigates and evaluates assumptions about the prior knowledge for solving unpractised probability problems; a representational scheme for addressing the co-ordination of sub-goals; a deictic problem representation to support online processing of environmental information, a meta-cognitive processing scheme to address self-argumentation and intention tracking and visual and spatial competences to address the requirements of diagrammatic reasoning. The implications of the cognitive model are discussed with regard to existing accounts of diagrammatic reasoning, probability problem solving (PPS), and unpractised problem solving.

Background: Estimating engagement levels from postural micromovements has been\ud summarized by some researchers as: increased proximity to the screen is a marker\ud for engagement, while increased postural movement is a signal for disengagement or\ud negative affect. However, these findings are inconclusive: the movement hypothesis\ud challenges other findings of dyadic interaction in humans, and experiments on the\ud positional hypothesis diverge from it.\ud Hypotheses: (1) Under controlled conditions, adding a relevant visual stimulus to an\ud auditory stimulus will preferentially result in Non-Instrumental Movement Inhibition (NIMI)\ud of the head. (2) When instrumental movements are eliminated and computer-interaction\ud rate is held constant, for two identically-structured stimuli, cognitive engagement (i.e.,\ud interest) will result in measurable NIMI of the body generally.\ud Methods: Twenty-seven healthy participants were seated in front of a computer monitor\ud and speakers. Discrete 3-min stimuli were presented with interactions mediated via a\ud handheld trackball without any keyboard, to minimize instrumental movements of the\ud participant’s body. Music videos and audio-only music were used to test hypothesis\ud (1). Time-sensitive, highly interactive stimuli were used to test hypothesis (2). Subjective\ud responses were assessed via visual analog scales. The computer users’ movements\ud were quantified using video motion tracking from the lateral aspect. Repeated measures\ud ANOVAs with Tukey post hoc comparisons were performed.\ud Results: For two equivalently-engaging music videos, eliminating the visual content\ud elicited significantly increased non-instrumental movements of the head (while also\ud decreasing subjective engagement); a highly engaging user-selected piece of favorite\ud music led to further increased non-instrumental movement. For two comparable reading\ud tasks, the more engaging reading significantly inhibited (42%) movement of the head\ud and thigh; however, when a highly engaging video game was compared to the boring reading, even though the reading task and the game had similar levels of interaction\ud (trackball clicks), only thigh movement was significantly inhibited, not head movement.\ud Conclusions: NIMI can be elicited by adding a relevant visual accompaniment to an\ud audio-only stimulus or by making a stimulus cognitively engaging. However, these results\ud presume that all other factors are held constant, because total movement rates can be\ud affected by cognitive engagement, instrumental movements, visual requirements, and\ud the time-sensitivity of the stimulus.

Emerging evidence indicates that prediction, instantiated at different perceptual levels, facilitate visual processing and enable prompt and appropriate reactions. Until now, the mechanisms underlying the effect of predictive coding at different stages of visual processing have still remained unclear. Here, we aimed to investigate early and late processing of spatial prediction violation by performing combined recordings of saccadic eye movements and fast event-related fMRI during a continuous visual detection task. Psychophysical reverse correlation analysis revealed that the degree of mismatch between current perceptual input and prior expectations is mainly processed at late rather than early stage, which is instead responsible for fast but general prediction error detection. Furthermore, our results suggest that conscious late detection of deviant stimuli is elicited by the assessment of prediction error's extent more than by prediction error per se. Functional MRI and functional connectivity data analyses indicated that higher-level brain systems interactions modulate conscious detection of prediction error through top-down processes for the analysis of its representational content, and possibly regulate subsequent adaptation of predictive models. Overall, our experimental paradigm allowed to dissect explicit from implicit behavioral and neural responses to deviant stimuli in terms of their reliance on predictive models.

A growing body of research suggests that social contextual factors such as desires and goals, affective states and stereotypes can shape early perceptual processes. We suggest that a generative Bayesian approach towards perception provides a powerful theoretical framework to accommodate how such high-level social factors can influence low-level perceptual processes in their earliest stages. We review experimental findings that show how social factors shape the perception and evaluation of people, behaviour, and socially relevant objects or information. Subsequently, we summarize the generative view of perception within the 'Bayesian brain', and show how such a framework can account for the pervasive effects of top-down social knowledge on social cognition. Finally, we sketch the theoretical and experimental implications of social predictive perception, indicating new directions for research on the effects and neurocognitive underpinnings of social cognition.

For people with synaesthesia, a percept or concept (inducer) triggers another experience (concurrent) which is usually in a different modality. The concurrent is automatic, and in the case of certain types of synaesthesia also consistent, however the relationship between the inducer and concurrent is not fully understood and shall be investigated in this thesis from different perspectives.\ud \ud The first is using hypnosis to suggest synaesthesia-like phenomenological experiences to participants, and measuring behavioural responses to see whether they behave in a similar manner to developmental synaesthetes. Results from hypnotic; 1) grapheme-colour (GC) synaesthesia; 2) motion-sound synaesthesia; suggest that phenomenological experiences similar to developmental synaesthesia can be experienced by highly susceptible participants, but is not associated with the same behaviour as developmental synaesthetes.\ud \ud Developmental GC synaesthetes were tested to determine whether a grapheme presented preconsciously binds with the concurrent colour to the extent that it influences behaviour or evokes the phenomenology of colour. Two techniques were used, gaze-contingent substitution (GCS) and continuous flash suppression (CFS). Using GCS, it was shown that although digits can be primed preconsciously, they don’t bind with their concurrent colour to influence behaviour. Nevertheless, many synaesthetes still experienced colours though they didn’t necessarily match the primed digit. CFS experiments showed that the colour of a grapheme’s concurrent, or whether the grapheme is presented in the correct or incorrect colour for that synaesthete, doesn’t influence the time for conscious perception of a grapheme, even though colour words presented in the correct colour are perceived faster than those in the wrong colour. Phenomenological differences were compared to the behavioural measures using questionnaires modified using factor analysis (the R-RSPA and R-ISEQ).\ud \ud Overall, inducers must be seen consciously for them to bind with the concurrent, and experiencing the phenomenology of synaesthesia is not sufficient to behave like a synaesthete.

Low frequency noise performance is the key indicator in determining the signal to noise ratio of a capacitively coupled sensor when used to acquire electroencephalogram signals. For this reason, a prototype Electric Potential Sensor device based on an auto-zero operational amplifier has been developed and evaluated. The absence of 1/f noise in these devices makes them ideal for use with signal frequencies ~10 Hz or less. The active electrodes are designed to be physically and electrically robust and chemically and biochemically inert. They are electrically insulated (anodized) and have diameters of 12 mm or 18 mm. In both cases, the sensors are housed in inert stainless steel machined housings with the electronics fabricated in surface mount components on a printed circuit board compatible with epoxy potting compounds. Potted sensors are designed to be immersed in alcohol for sterilization purposes. A comparative study was conducted with a commercial wet gel electrode system. These studies comprised measurements of both free running electroencephalogram and Event Related Potentials. Quality of the recorded electroencephalogram was assessed using three methods of inspection of raw signal, comparing signal to noise ratios, and Event Related Potentials noise analysis. A strictly comparable signal to noise ratio was observed and the overall conclusion from these comparative studies is that the noise performance of the new sensor is appropriate.

Ackermann et al. mention the “acquisition of species-atypical sounds” in apes without any discussion. In our commentary, we demonstrate that these atypical sounds in chimpanzees not only include laryngeal sounds, but also have a major significance regarding the origins of language, if we consider looking at their context of use, their social properties, their relations with gestures, their lateralization, and their neurofunctional correlates as well.