From cognition to consciousness

This paper proposes an extension of scientific horizons in the study of animal behavior and cognition to include conscious experiences. From this perspective animals are best appreciated as actors rather than passive objects. A major adaptive function of their central nervous systems may be simple, but conscious and rational, thinking about alternative actions and choosing those the animal believes will get what it wants, or avoid what it dislikes or fears. Versatile adjustment of behavior in response to unpredictable challenges provides strongly suggestive evidence of simple but conscious thinking. And especially significant objective data about animal thoughts and feelings are already available, once communicative signals are recognized as evidence of the subjective experiences they often convey to others. The scientific investigation of human consciousness has undergone a renaissance in the 1990s, as exemplified by numerous symposia, books and two new journals. The neural correlates of cognition appear to be basically similar in all central nervous systems. Therefore other species equipped with very similar neurons, synapses, and glia may well be conscious. Simple perceptual and rational conscious thinking may be at least as important for small animals as for those with large enough brains to store extensive libraries of behavioral rules. Perhaps only in “megabrains” is most of the information processing unconscious. Received: 23 March 1998 / Accepted: 11 April 1998     

Tracking the processes behind conscious perception: a review of event-related potential correlates of visual consciousness

Event-related potential (ERP) studies have attempted to discover the processes that underlie conscious visual perception by contrasting ERPs produced by stimuli that are consciously perceived with those that are not. Variability of the proposed ERP correlates of consciousness is considerable: the earliest proposed ERP correlate of consciousness (P1) coincides with sensory processes and the last one (P3) marks postperceptual processes. A negative difference wave called visual awareness negativity (VAN), typically observed around 200 ms after stimulus onset in occipitotemporal sites, gains strong support for reflecting the processes that correlate with, and possibly enable, aware visual perception. Research suggests that the early parts of conscious processing can proceed independently of top-down attention, although top-down attention may modulate visual processing even before consciousness. Evidence implies that the contents of consciousness are provided by interactions in the ventral stream, but indispensable contributions from dorsal regions influence already low-level visual responses.     

Measuring consciousness: task accuracy and awareness as sigmoid functions of stimulus duration

When consciousness is examined using subjective ratings, the extent to which processing is conscious or unconscious is often estimated by calculating task performance at the subjective threshold or by calculating the correlation between accuracy and awareness. However, both these methods have certain limitations. In the present article, we propose describing task accuracy and awareness as functions of stimulus intensity (thus obtaining an accuracy and an awareness curve) as suggested by Koch and Preuschoff (2007). The estimated lag between the curves describes how much stimulus intensity must increase for awareness to change proportionally as much as accuracy and the slopes of the curves are used to assess how fast accuracy and awareness increases and whether awareness is dichotomous. The method is successfully employed to assess consciousness characteristics on data from four different awareness scales.     

Implicit processing of tactile information: evidence from the tactile change detection paradigm

People can maintain accurate representations of visual changes without necessarily being aware of them. Here, we investigate whether a similar phenomenon (implicit change detection) also exists in touch. In Experiments 1 and 2, participants detected the presence of a change between two consecutively-presented tactile displays. Tactile change blindness was observed, with participants failing to report the presence of tactile change. Critically, however, when participants had to make a forced choice response regarding the number of stimuli presented in the two displays, their performance was significantly better than chance (i.e., implicit change detection was observed). Experiment 3 demonstrated that tactile change detection does not necessarily involve a shift of spatial attention toward the location of change, regardless of whether the change is explicitly detected. We conclude that tactile change detection likely results from comparing representations of the two displays, rather than by directing spatial attention to the location of the change.     

Further evidence for the efficacy of a metacognitive group training in schizophrenia

Metacognitive training (MCT) for patients with schizophrenia is a novel psychological group treatment targeting cognitive biases putatively involved in the pathogenesis of schizophrenia (e.g. jumping to conclusions, overconfidence in errors). Its eight modules are available cost-free online in many languages. In the present study, 36 subacute or remitted patients were randomly allocated to either the MCT or a wait-list group who received treatment-as-usual (TAU). Baseline and post assessments were 8 weeks apart and were performed blind to group status. MCT showed significantly greater improvement on the following parameters relative to the TAU group: delusion distress (PSYRATS), memory and social quality of life. In the MCT group, the rate of jumping to conclusions bias was reduced after training. No differences occurred on the PANSS. The present study confirms prior reports that MCT exerts beneficial effects on some cognitive and symptomatic parameters.     

The role of primordial emotions in the evolutionary origin of consciousness

Primordial emotions are the subjective element of the instincts which are the genetically programmed behaviour patterns which contrive homeostasis. They include thirst, hunger for air, hunger for food, pain and hunger for specific minerals etc.There are two constituents of a primordial emotion—the specific sensation which when severe may be imperious, and the compelling intention for gratification by a consummatory act. They may dominate the stream of consciousness, and can have plenipotentiary power over behaviour.It is hypothesized that early in animal evolution complex reflex mechanisms in the basal brain subserving homeostatic responses, in concert with elements of the reticular activating system subserving arousal, melded functionally with regions embodied in the progressive rostral development of the telencephalon. This included the emergent limbic and paralimbic areas, and the insula. This phylogenetically ancient organization subserved the origin of consciousness as the primordial emotion, which signalled that the organisms existence was immediately threatened. Neuroimaging confirms major activations in regions of the basal brain during primordial emotions in humans. The behaviour of decorticate humans and animals is discussed in relation to the possible existence of primitive awareness.Neuroimaging of the primordial emotions reveals that rapid gratification of intention by a consummatory act such as ingestion causes precipitate decline of both the initiating sensation and the intention. There is contemporaneous rapid disappearance of particular regions of brain activation which suggests they may be part of the jointly sufficient and severally necessary activations and deactivations which correlate with consciousness [Crick, F. & Koch, C. (2003). A framework for consciousness. Nature Neuroscience, 6, 119–126].     

Ethics and the Science of Animal Minds

Ethicists have commonly appealed to science to bolster their arguments for elevating the moral status of nonhuman animals. I describe a framework within which I take many ethicists to be making such appeals. I focus on an apparent gap in this framework between those properties of animals that are part of the scientific consensus, and those to which ethicists typically appeal in their arguments. I will describe two different ways of diminishing the appearance of the gap, and argue that both of them present challenges to ethicists seeking a firm scientific basis for their claims about the moral status of animals. I argue that more clarity about the role of appeals to science by applied ethicists leads to questions about the effectiveness of such appeals, and that these questions might best be pursued empirically.     

Emotion colors time perception unconsciously

Emotion modulates our time perception. So far, the relationship between emotion and time perception has been examined with visible emotional stimuli. The present study investigated whether invisible emotional stimuli affected time perception. Using continuous flash suppression, which is a kind of dynamic interocular masking, supra-threshold emotional pictures were masked or unmasked depending on whether the retinal position of continuous flashes on one eye was consistent with that of the pictures on the other eye. Observers were asked to reproduce the perceived duration of a frame stimulus that was concurrently presented with a masked or unmasked emotional picture. As a result, negative emotional stimuli elongated the perceived duration of the frame stimulus in comparison with positive and neutral emotional stimuli, regardless of the visibility of emotional pictures. These results suggest that negative emotion unconsciously accelerates an internal clock, altering time perception.     

Is conscious perception gradual or dichotomous? A comparison of report methodologies during a visual task

In a recent article, [Sergent, C. &; Dehaene, S. (2004). Is consciousness a gradual phenomenon? Evidence for an all-or-none bifurcation during the attentional blink, Psychological Science, 15(11), 720–729] claim to give experimental support to the thesis that there is a clear transition between conscious and unconscious perception. This idea is opposed to theoretical arguments that we should think of conscious perception as a continuum of clarity, with e.g., fringe conscious states [Mangan, B. (2001). Sensation’s ghost—the non-sensory “fringe” of consciousness, Psyche, 7, 18]. In the experimental study described in this article, we find support for this opposite notion that we should have a parsimonious account of conscious perception. Our reported finding relates to the hypothesis that there is more than one perceptual threshold [Merikle, P.M., Smilek, D. &; Eastwood, J.D. (2001). Perception without awareness: perspectives from cognitive psychology, Cognition, 79, 115–134], but goes further to argue that there are different “levels” of conscious perception.     

Schizophrenia, dissociation, and consciousness

Current thinking suggests that dissociation could be a significant comorbid diagnosis in a proportion of schizophrenic patients with a history of trauma. This potentially may explain the term “schizophrenia” in its original definition by Bleuler, as influenced by his clinical experience and personal view. Additionally, recent findings suggest a partial overlap between dissociative symptoms and the positive symptoms of schizophrenia, which could be explained by inhibitory deficits. In this context, the process of dissociation could serve as an important conceptual framework for understanding schizophrenia, which is supported by current neuroimaging studies and research of corollary discharges. These data indicate that the original conception of “split mind” may be relevant in an updated context. Finally, recent data suggest that the phenomenal aspects of dissociation and conscious disintegration could be related to underlying disruptions of connectivity patterns and neural integration.     

Expertise and the evolution of consciousness

This paper argues that expertise can be used as an indicator of consciousness in humans and other animals. The argument is based on the following observations: (1) expertise and skill acquisition require deliberate practice; and (2) the characteristics of deliberate practice such as performance evaluation against a more proficient model, retention of voluntary control over actions, self-monitoring, goal-setting, error-detection and correction, and the construction of hierarchically organized retrieval structures are outside of the currently understood bounds of unconscious processing. Thus, to the extent that evidence of expertise exists in an organism, evidence of conscious experience is also present. Two important implications arise from this conclusion: (1) evidence of expertise can be used as the basis for cross-species comparisons of consciousness; and (2) the evolution of human consciousness can be assessed using fossil evidence of skilled behavior as a measure of consciousness.     

The electrophysiological correlates of stimulus visibility and metacontrast masking

There are conflicting views concerning the electrophysiological correlates of visual consciousness. Whereas one view considers a relatively late positive deflection (LP) as a primary correlate of consciousness, another model links consciousness with earlier negativity (VAN). The present experiment utilized metacontrast masking in investigating the electrophysiological correlates of visual consciousness. The participants were presented with target-mask sequences in three stimulus onset asynchronies. The target stimuli were followed by either a metacontrast mask or a similar-looking, but ineffective pseudomask. The results showed that the first deflection that correlated with target visibility was VAN which was followed by LP. We argue that the VAN is the primary correlate target visibility, while the LP reflects later, postperceptual processing stages.     

A critical review of the physicalistic approaches of the mind and consciousness

The aim of this paper is to construct a critical evaluation of the advantages and disadvantages of the physicalistic theory concerning mental phenomena and consciousness. Physicalism can, better than other theories, explain mental phenomena, such as intentionality and reasonability of human beings and other biological organisms. Modern neuroscience corroborates the conviction that the brain is a physical mind capable of giving meaning to, evaluating and further cognitively and behaviorally transforming complex aspects of the world. On the other hand, the emergence of consciousness from brain states seems to be a paradoxical, intransparent, physical coincidence hardly explained by the mental function of the brain at the physical level. Moreover, the intentionality and reasonability of psychic phenomena per se cannot be explained as a repercussion of the same attributes characterizing the brain function. In conclusion, the old debate between physicalism and other philosophical theories remains open. It can be expected that the progress of sciences will inspire novel approaches to the problem of the relations between matter, mind and consciousness.