In the ongoing research of the functions of consciousness, special emphasis has been put on integration of information: the ability to combine different signals into a coherent, unified one. Several theories of consciousness hold that this ability depends on – or at least goes hand in hand with – conscious processing. Yet some empirical findings have suggested otherwise, claiming that integration of information could take place even without awareness. Trying to reconcile this apparent contradiction, the “windows of integration” hypothesis claims (...) that conscious access enables signal processing over large integration windows. The hypothesis applies to integration windows defined either temporally, spatially, or semantically. In this review, we explain the hypothesis and re-examine it in light of new studies published since it was suggested. In line with the hypothesis, these studies provide compelling evidence for unconscious integration, but also demonstrate its limits with respect to time, space, and semantic distance. The review further highlights open questions that still need to be pursued to demonstrate the applicability of the WOI hypothesis as a guiding principle for understanding the depth and scope of unconscious processes. (shrink)

After reviewing the literature on current knowledge about consciousness in humans, we present a state-of-the art discussion on consciousness and related key concepts in animals. Obviously much fewer publications are available on non-human species than on humans, most of them relating to laboratory or wild animal species, and only few to livestock species. Human consciousness is by definition subjective and private. Animal consciousness is usually assessed through behavioural performance. Behaviour involves a wide array of cognitive processes that have to be (...) assessed separately using specific experimental protocols. Accordingly, several processes indicative of the presence of consciousness are discussed: perception and cognition, awareness of the bodily-self, self-related knowledge of the environment (including social environment). When available, specific examples are given in livestock species. Next, we review the existing evidence regarding neuronal correlates of consciousness, and emphasize the difficulty of linking aspects of consciousness to specific neural structures across the phyla because high-level cognitive abilities may have evolved independently along evolution. Several mammalian brain structures (cortex and midbrain) are involved in the manifestations of consciousness, while the equivalent functional structures for birds and fishes would likely be the pallium/tectum and midbrain. Caution is required before excluding consciousness in species not having the same brain structures as the mammalian ones as different neural architectures may mediate comparable processes. Finally, specific neurophysiological mechanisms appear to be strongly linked to the emergence of consciousness, namely neural synchrony and neural feedback. Considering the limited amount of data available and the few animal species studied so far, we conclude that different manifestations of consciousness can be observed in animals but that further refinement is still needed to characterize their level and content in each species. Further research is required to clarify these issues, especially in livestock species. (shrink)

Contrasting the properties of conscious and unconscious processes is crucial for understanding how consciousness occurs in the brain. In this chapter, we review the theoretical framework and empirical methods used to delineate and contrast conscious vs. unconscious perception. After outlining the main approaches to measure unconscious influences on brain and behavior, we describe some of the psychophysical tools employed to render stimuli unconscious, including the depletion of sensory signals, attentional resources, and vigilance states. We then provide an overview of the (...) extent and limits of unconscious perception, and conclude on the future of the contrastive approach to the study of consciousness. (shrink)

A target question for the scientific study of consciousness is how dimensions of consciousness, such as the ability to feel pain and pleasure or reflect on one’s own experience, vary in different states and animal species. Considering the tight link between consciousness and moral status, answers to these questions have implications for law and ethics. Here we point out that given this link, the scientific community studying consciousness may face implicit pressure to carry out certain research programs or interpret results (...) in ways that justify current norms rather than challenge them. We show that because consciousness largely determines moral status, the use of nonhuman animals in the scientific study of consciousness introduces a direct conflict between scientific relevance and ethics—the more scientifically valuable an animal model is for studying consciousness, the more difficult it becomes to ethically justify compromises to its well-being for consciousness research. Finally, in light of these considerations, we call for a discussion of the immediate ethical corollaries of the body of knowledge that has accumulated and for a more explicit consideration of the role of ideology and ethics in the scientific study of consciousness. (shrink)

To what level are invisible stimuli processed by the brain in the absence of conscious awareness? It is widely accepted that simple visual properties of invisible stimuli are processed; however, the existence of higher-level unconscious processing (e.g., involving semantic or executive functions) remains a matter of debate. Several methodological factors may underlie the discrepancies found in the literature, such as different levels of conservativeness in the definition of "unconscious" or different dependent measures of unconscious processing. In this research topic, we (...) are particularly interested in yet another factor: inherent differences in the amount of information let through by different suppression techniques. In the same conditions of well-controlled, conservatively established invisibility, can we show that some of the techniques in the "psychophysical magic" arsenal (e.g., masking, but also visual crowding, attentional blink, etc.) reliably lead to higher-level unconscious processing than others (e.g., interocular suppression)? Some authors have started investigating this question, using multiple techniques in similar settings. We argue that this approach should be extended and refined. Indeed, in order to delineate the frontiers of the unconscious mind using a contrastive method, one has to disentangle the limits attributable to unawareness itself, and those attributable to the technique inducing unawareness. The scope of this research topic is to provide a platform for scientists to contribute insights and further experiments addressing this fundamental question. (shrink)