Visual experience can sometimes depart from visual performance, providing a powerful lens into the mechanisms generating conscious perception. In one proposed dissociation—subjective inflation—unattended locations in the periphery appear stronger than attended ones despite equated performance. Subjective inflation has played a central role in motivating theories of consciousness that reject the...
As the field of consciousness science matures, the research agenda has expanded from an initial focus on the neural correlates of consciousness, to developing and testing theories of consciousness. Several theories have been put forward, each aiming to elucidate the relationship between consciousness and brain function. However, there is an ongoing, intense debate regarding whether these...
A conscious being has a subjective point of view on the world and on its own body. This idea of a ‘point of view’ is easiest to grasp in the case of vision. Ernst Mach, in the Analysis of Sensations, famously attempted to draw his own visual point of view (Figure 1). But there is far more to human subjective experience than vision. Our subjective point of view includes sounds, odours, tastes,...
Evidence for all sorts of cognition in animals is mounting. But is this accompanied by conscious sensation or phenomenology? To answer that question, it is noted that consciousness to us presents itself as a contrast: we are asleep or awake, we either see something or we don't, each state or condition accompanied by distinct neural correlates. The contrast implicitly holds there is conscious...
Various theories for the neural basis of consciousness have been proposed, suggesting a diversity of neural signs and mechanisms. We ask to what extent this diversity is real, or whether many theories share the same basic ideas with a potential for convergence towards a more unified theory of the neural basis of consciousness. For that purpose, we review and compare the various neural signs,...
Visual functions are reviewed that coincide with conscious as opposed to unconscious vision. Four stages of vision are identified, going from the fully invisible, to subjectively invisible, unattended, and clearly visible. It is proposed that feature extraction, categorization, and some aspects of visual inference occur during full and subjective invisibility. Functions related to perceptual...
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.
Significant progress has been made in the study of consciousness. Promising theories have been developed and a wealth of experimental data has been generated, both guiding us towards a better understanding of this complex phenomenon. However, new challenges have surfaced. Is visual consciousness about the seeing or the knowing that you see? Controversy about whether the conscious experience is...
In their Review “What is consciousness, and could machines have it?” (27 October 2017, p. [486][1]), S. Dehaene et al. argue that the science of consciousness indicates that we are not on the verge of creating conscious machines. However, Dehaene et al. ask and answer the wrong questions. To
The split-brain phenomenon is caused by the surgical severing of the corpus callosum, the main route of communication between the cerebral hemispheres. The classical view of this syndrome asserts that conscious unity is abolished. The left hemisphere consciously experiences and functions independently of the right hemisphere. This view is a cornerstone of current consciousness research. In this...
Is conscious visual perception limited to the locations that a person attends? The remarkable phenomenon of change blindness, which shows that people miss nearly all unattended changes in a visual scene, suggests the answer is yes. However, change blindness is found after visual interference (a mask or a new scene), so that subjects have to rely on working memory (WM), which has limited...
In extensive studies with two split-brain patients we replicate the standard finding that stimuli cannot be compared across visual half-fields, indicating that each hemisphere processes information independently of the other. Yet, crucially, we show that the canonical textbook findings that a split-brain patient can only respond to stimuli in the left visual half-field with the left hand, and...
The goal of consciousness research is to reveal the neural basis of phenomenal experience. To study phenomenology, experimenters seem obliged to ask reports from the subjects to ascertain what they experience. However, we argue that the requirement of reports has biased the search for the neural correlates of consciousness over the past decades. More recent studies attempt to dissociate neural...
How do expectations influence transitions between unconscious and conscious perceptual processing? According to the influential predictive processing framework, perceptual content is determined by predictive models of the causes of sensory signals. On one interpretation, conscious contents arise when predictive models are verified by matching sensory input (minimizing prediction error). On...
The scientific study of consciousness has gained much interest over the past several decades. Here, we provide a primer on the topic by introducing the most commonly used concepts, the most prominent scientific theories, and an overview of broadly used methods of studying consciousness. With a focus on visual perception, we discuss the distinction between phenomenology and cognitive...
Nobel Laureate Paul Krugman once remarked that engaging the public about economic theories is hard, partly because everybody feels they are entitled to opine about the economy even if they have no formal training in economics (see: http://web.mit.edu/krugman/www/virus.html). Perhaps because we are all conscious, the same sometimes happens in the field of consciousness research. Like Krugman, we...
The cognitive signature of unconscious processes is hotly debated recently. Generally, consciousness is thought to mediate flexible, adaptive and goal-directed behavior, but in the last decade unconscious processing has rapidly gained ground on traditional conscious territory. In this study we demonstrate that the scope and impact of unconscious information on behavior and brain activity can be...
Is there consciousness in machines? Or in animals? What happens to consciousness when we are asleep, or in vegetative state? These are just a few examples of the many questions about consciousness that are troubling scientists and laypersons alike. Moreover, these questions share a striking feature: They seem to have been around forever, yet neither science nor philosophy has been able to...
A proper science of consciousness combines all the available evidence - either coming from introspection, behavior, neuroscience or theory - in such a way that a 'best of all worlds' perspective is attained. Introspection shows us that qualia are all about perceptual organization. Neuroscience can then tell us where and when perceptual organization occurs, and whether this is independent of...
Cognitive control processes involving prefrontal cortex allow humans to overrule and inhibit habitual responses to optimize performance in new and challenging situations, and traditional views hold that cognitive control is tightly linked with consciousness. We used functional magnetic resonance imaging to investigate to what extent unconscious "no-go" stimuli are capable of reaching cortical...