Attention versus consciousness in the visual brain: differences in conception, phenomenology, behavior, neuroanatomy, and physiology.

A common confound between consciousness and attention makes it difficult to think clearly about recent advances in the understanding of the visual brain. Visual consciousness involves phenomenal experience of the visual world, but visual attention is more plausibly treated as a function that selects and maintains the selection of potential conscious contents, often unconsciously. In the same sense, eye movements select conscious visual events, which are not the same as conscious visual experience. According to common sense, visual experience is consciousness, and selective processes are labeled as attention. The distinction is reflected in very different behavioral measures and in very different brain anatomy and physiology. Visual consciousness tends to be associated with the "what" stream of visual feature neurons in the ventral temporal lobe. In contrast, attentional selection and maintenance are mediated by other brain regions, ranging from superior colliculi to thalamus, prefrontal cortex, and anterior cingulate. The author applied the common-sense distinction between attention and consciousness to the theoretical positions of M. I. Posner (1992, 1994) and D. LaBerge (1997, 1998) to show how it helps to clarify the evidence. He concluded that clarity of thought is served by calling a thing by its proper name.     

简论里贝特的意识理论

里贝特是人类意识和自由意志的实验研究领域的一个卓越的、先驱性的神经科学家。里贝特的意识研究工作涉及如下四个方面：（1）关于意识研究的认识论原则;（2）对意识现象本性的界定;（3）意识机制的时控理论;（4）对自由意志的阐释和有意识的心智场理论。里贝特的意识研究独树一帜,其时控理论具有坚实可信的实验证据,它从时间维度揭示了有意识的主观体验以及无意识的心智功能与神经活动之间的时间机制。     

New evidence of animal consciousness

This paper reviews evidence that increases the probability that many animals experience at least simple levels of consciousness. First, the search for neural correlates of consciousness has not found any consciousness-producing structure or process that is limited to human brains. Second, appropriate responses to novel challenges for which the animal has not been prepared by genetic programming or previous experience provide suggestive evidence of animal consciousness because such versatility is most effectively organized by conscious thinking. For example, certain types of classical conditioning require awareness of the learned contingency in human subjects, suggesting comparable awareness in similarly conditioned animals. Other significant examples of versatile behavior suggestive of conscious thinking are scrub jays that exhibit all the objective attributes of episodic memory, evidence that monkeys sometimes know what they know, creative tool-making by crows, and recent interpretation of goal-directed behavior of rats as requiring simple nonreflexive consciousness. Third, animal communication often reports subjective experiences. Apes have demonstrated increased ability to use gestures or keyboard symbols to make requests and answer questions; and parrots have refined their ability to use the imitation of human words to ask for things they want and answer moderately complex questions. New data have demonstrated increased flexibility in the gestural communication of swarming honey bees that leads to vitally important group decisions as to which cavity a swarm should select as its new home. Although no single piece of evidence provides absolute proof of consciousness, this accumulation of strongly suggestive evidence increases significantly the likelihood that some animals experience at least simple conscious thoughts and feelings. The next challenge for cognitive ethologists is to investigate for particular animals the content of their awareness and what life is actually like, for them.Donald R. Griffin died on 7 November 2003     

Inductive parsimony and the Methodological Argument

Studies on so-called Change Blindness and Inattentional Blindness have been taken to establish the claim that conscious perception of a stimulus requires the attentional processing of that stimulus. One might contend, against this claim, that the evidence only shows attention to be necessary for the subject to have access to the contents of conscious perception and not for conscious perception itself. This "Methodological Argument" is gaining ground among philosophers who work on attention and consciousness, such as Christopher Mole. I find that, without the supporting evidence of inaccessible consciousness, this argument collapses into an indefensible form of inductive parsimony. The Methodological Argument is thus shown to be unsuccessful when used against the claim that attention is required for conscious perception, though I suggest that it may be successful against the more ambitious claim that attention is necessary for all conscious experience.     

The modal breadth of consciousness

In this paper, I argue that the intentional structure of typical human conscious experience has “modal breadth”—that the contents of experience typically include alternate possibilities. I support this claim with analyses of conscious mental processes such as the perception of temporally extended events, persistent objects, and causality, and the experience of bodily agency. While modal breadth may not be strictly necessary for consciousness per se, it is essential to many cognitive processes that are pervasive and functionally important to normal human consciousness.     

Consciousness cannot be separated from function

Numerous theories of consciousness hold that there are separate neural correlates of conscious experience and cognitive function, aligning with the assumption that there are 'hard' and 'easy' problems of consciousness. Here, we argue that any neurobiological theory based on an experience/function division cannot be empirically confirmed or falsified and is thus outside the scope of science. A 'perfect experiment' illustrates this point, highlighting the unbreachable boundaries of the scientific study of consciousness. We describe a more nuanced notion of cognitive access that captures personal experience without positing the existence of inaccessible conscious states. Finally, we discuss the criteria necessary for forming and testing a falsifiable theory of consciousness.     

Neural correlates of consciousness reconsidered

It is widely accepted among philosophers that neuroscientists are conducting a search for the neural correlates of consciousness, or NCC. Chalmers (2000) conceptualized this research program as the attempt to correlate the contents of conscious experience with the contents of representations in specific neural populations. A notable claim on behalf of this interpretation is that the neutral language of "correlates" frees us from philosophical disputes over the mind/body relation, allowing the science to move independently. But the experimental paradigms and explanatory canons of neuroscience are not neutral about the mechanical relation between consciousness and the brain. I argue that NCC research is best characterized as an attempt to locate a causally relevant neural mechanism and not as an effort to identify a discrete neural representation, the content of which correlates with some actual experience. It might be said that the first C in "NCC" should stand for "causes" rather than "correlates."     

Experiencing organisms: from mineness to subject of experience

Many philosophers hold that phenomenally conscious experiences involve a sense of mineness, since experiences like pain or hunger are immediately presented as mine. What can be said about this mineness, and does acceptance of this feature commit us to the existence of a subject or self? If yes, how should we characterize this subject? This paper considers the possibility that, (1) to the extent that we accept this feature, it provides us with a minimal notion of a subject of experience, and that (2) the phenomenological subject of experience, as it is represented in conscious experience, is the organism. While many philosophers agree that the metaphysical subject of experience is the animal, this claim is much less widespread, maybe even counterintuitive. The argument for this claim alludes to the structure of phenomenal consciousness and to recent work in cognitive science concerning the embodied character of consciousness and cognition. To illustrate the problems of current controversies, not only several recent rejections of a subject of experience are critically discussed, but also Hume’s famous rejection of a subject is criticized making use of epistemological aspects from Kant’s philosophy of mind. The final section situates the present discussion in the context of recently popular predictive coding accounts of perception and perceptual experience.     

The time of consciousness and vice versa

The temporal granularity of consciousness may be far less fine than the real-time information processing mechanisms that underlie our sensitivity to small temporal differences. It is suggested that conscious time perception, like space perception, is subject to errors that belie a unitary underlying representation. E. R. Clay's (The Alternative: A Study in Psychology, 1882) concept of the "specious present," an extended moment represented in consciousness, is suggested as an alternative to the more common notion of instantaneous experience that underlies much reasoning based on the "time of arrival" in consciousness.     

From behaviour to consciousness: Translating what animals do to what animals think

Cognitive ethology, an interdisciplinary and comparative branch of zoology, is concerned with the influence of conscious awareness and intention on animal behaviour. It enquires into the evolutionary value of consciousness. However, consciousness is hard to define and any account of animal behaviour based on it will need to take into account both the physical mechanisms that allow for consciousness, and also consider whether we can have knowledge of the phenomenal experience of consciousness in other species. While the first consideration can be investigated scientifically, phenomenal experience needs to be inferred from behaviour, since most animals are not capable of communicating this experience directly. In fact, many accounts of animal behaviour, behavioural ecology in particular, argue that we cannot accurately explain animal behaviour with relation to thoughts or feelings and conscious awareness of them. Rather, we must concern ourselves with what can be objectively observed and measured. Cognitive ethology, however, argues that we cannot give accurate accounts of complex animal behaviour, for example social interactions or tool use, without taking consciousness into account. In this article I will argue that one can justifiably assign and study consciousness in animals through their behaviour, and that an account of certain animals’ behaviour is incomplete without reference to conscious awareness. In other words, behavioural ecology is essentially flawed as it gives, in certain cases, ultimately incorrect accounts of animal behaviour. Firstly it cannot distinguish between behaviour of more and less conscious animals, and secondly, by avoiding any mention of consciousness, it narrows its own scope, and finally cannot explain complex behaviours such as learning in any meaningful way.     

Beyond free will: The embodied emergence of conscious agency

Is it possible to reconcile the concept of conscious agency with the view that humans are biological creatures subject to material causality? The problem of conscious agency is complicated by the tendency to attribute autonomous powers of control to conscious processes. In this paper, we offer an embodied process model of conscious agency. We begin with the concept of embodied emergence – the idea that psychological processes are higher-order biological processes, albeit ones that exhibit emergent properties. Although consciousness, experience, and representation are emergent properties of higher-order biological organisms, the capacity for hierarchical regulation is a property of all living systems. Thus, while the capacity for consciousness transforms the process of hierarchical regulation, consciousness is not an autonomous center of control. Instead, consciousness functions as a system for coordinating novel representations of the most pressing demands placed on the organism at any given time. While it does not regulate action directly, consciousness orients and activates preconscious control systems that mediate the construction of genuinely novel action. Far from being an epiphenomenon, consciousness plays a central albeit non-autonomous role in psychological functioning.     

Psychic reality and the nature of consciousness

In this paper we make the case for a psychoanalytically informed reconsideration of the phenomena of consciousness. Classically, following Freud, who viewed consciousness as merely a reflection or perception of unconscious mental activity, psychoanalysts have tended to regard a focus on conscious experience as potentially reductionistic and at risk of overlooking the mind's deeper structures. We describe the case of Mr K, a patient who experienced disturbances of consciousness that forced us to consider the possibility that the capacity to experience ourselves as conscious, intentional agents in a coherent world of objects is not merely a modality of perception but rather a maturational and developmental achievement that to some degree depends on adequate experiences of caregiving and is vital in ensuring the possibility of human communication. As such, it is a capacity that is vulnerable to experiences of neglect and maltreatment. We suggest that as well as compromising the capacity to think about one's own and other people's feelings, such experiences may have the further adverse consequence of leading the individual to experience and risk becoming conscious of certain dangerously maladaptive, destructive states of mind which in normal development remain inaccessible to conscious experience. Phenomenologically, such states of mind are experienced as fragmentation and disturbances of consciousness. We discuss the clinical implications of these reflections and the limitations they place on psychoanalytic work in the context of their impact on the work with Mr K.     

Identifying hallmarks of consciousness in non-mammalian species

Most early studies of consciousness have focused on human subjects. This is understandable, given that humans are capable of reporting accurately the events they experience through language or by way of other kinds of voluntary response. As researchers turn their attention to other animals, "accurate report" methodologies become increasingly difficult to apply. Alternative strategies for amassing evidence for consciousness in non-human species include searching for evolutionary homologies in anatomical substrates and measurement of physiological correlates of conscious states. In addition, creative means must be developed for eliciting behaviors consistent with consciousness. In this paper, we explore whether necessary conditions for consciousness can be established for species as disparate as birds and cephalopods. We conclude that a strong case can be made for avian species and that the case for cephalopods remains open. Nonetheless, a consistent effort should yield new means for interpreting animal behavior.     

Towards a pluralistic neurobiological understanding of consciousness

Theories of consciousness are often based on the assumption that a single, unified neurobiological account will explain different types of conscious awareness. However, recent findings show that, even within a single modality such as conscious visual perception, the anatomical location, timing, and information flow of neural activity related to conscious awareness vary depending on both external and internal factors. This suggests that the search for generic neural correlates of consciousness may not be fruitful. I argue that consciousness science requires a more pluralistic approach and propose a new framework: joint determinant theory (JDT). This theory may be capable of accommodating different brain circuit mechanisms for conscious contents as varied as percepts, wills, memories, emotions, and thoughts, as well as their integrated experience.     

Pain, dissociation and subliminal self-representations

According to recent evidence, neurophysiological processes coupled to pain are closely related to the mechanisms of consciousness. This evidence is in accordance with findings that changes in states of consciousness during hypnosis or traumatic dissociation strongly affect conscious perception and experience of pain, and markedly influence brain functions. Past research indicates that painful experience may induce dissociated state and information about the experience may be stored or processed unconsciously. Reported findings suggest common neurophysiological mechanisms of pain and dissociation and point to a hypothesis of dissociation as a defense mechanism against psychological and physical pain that substantially influences functions of consciousness. The hypothesis is also supported by findings that information can be represented in the mind/brain without the subject's awareness. The findings of unconsciously present information suggest possible binding between conscious contents and self-functions that constitute self-representational dimensions of consciousness. The self-representation means that certain inner states of own body are interpreted as mental and somatic identity, while other bodily signals, currently not accessible to the dominant interpreter's access are dissociated and may be defined as subliminal self-representations. In conclusion, the neurophysiological aspects of consciousness and its integrative role in the therapy of painful traumatic memories are discussed.     

Temporal organization of the brain: Neurocognitive mechanisms and clinical implications

The synchrony between the individual brain and its environment is maintained by a system of internal clocks that together reflect the temporal organization of the organism. Extending the theoretical work of Edelman and others, the temporal organization of the brain is posited as functioning through "re-entry" and "temporal tagging" and binds the wide range of possible times to a unified cognitive experience which is held in unison with the outside world. Dysfunction in this system is reflected in the temporal discord seen in cases of aging, sleep disorder, jet-lag, and shift-work, as well as in mental disorders and drug-induced changes in consciousness. The extent to which neuroendocrine structures contribute to the neurocognitive mechanisms which underlie consciousness has so far not been explored. Therefore, neuroendocrine mechanisms contributing to the temporal organization of the brain are reviewed. It is concluded that time-and its neuroendocrine correlate melatonin-is a binding principle for organizing conscious experience.     

Emotion and consciousness

Consciousness and emotion feature prominently in our personal lives, yet remain enigmatic. Recent advances prompt further distinctions that should provide more experimental traction: we argue that emotion consists of an emotion state (functional aspects, including emotional response) as well as feelings (the conscious experience of the emotion), and that consciousness consists of level (e.g. coma, vegetative state and wakefulness) and content (what it is we are conscious of). Not only is consciousness important to aspects of emotion but structures that are important for emotion, such as brainstem nuclei and midline cortices, overlap with structures that regulate the level of consciousness. The intersection of consciousness and emotion is ripe for experimental investigation, and we outline possible examples for future studies.     

Recollective experience in word and nonword recognition

The functional relationship between memory and consciousness was investigated in two experiments in which subjects indicated when recognizing an item whether they could consciously recollect its prior occurrence in the study list or recognized it on some other basis, in the absence of conscious recollection. Low-frequency words, relative to high-frequency words, enhanced recognition accompanied by conscious recollection but did not influence recognition in the absence of conscious recollection. By contrast, nonwords compared with words enhanced recognition in the absence of conscious recollection and reduced recognition accompanied by conscious recollection. A third experiment showed that confidence judgments in recognizing nonword targets corresponded with recognition performance, not with recollective experience. These measures of conscious awareness therefore tap qualitatively different components of memory, not some unitary dimension such as "trace strength." The findings are interpreted as providing further support for the distinction between episodic memory and other memory systems, and also as providing more qualified support for theories that assume that recognition memory entails two components, one of which may also give rise to priming effects in implicit memory.