Empirical support for higher-order theories of conscious awareness

Higher-order theories of consciousness argue that conscious awareness crucially depends on higher-order mental representations that represent oneself as being in particular mental states. These theories have featured prominently in recent debates on conscious awareness. We provide new leverage on these debates by reviewing the empirical evidence in support of the higher-order view. We focus on evidence that distinguishes the higher-order view from its alternatives, such as the first-order, global workspace and recurrent visual processing theories. We defend the higher-order view against several major criticisms, such as prefrontal activity reflects attention but not awareness, and prefrontal lesion does not abolish awareness. Although the higher-order approach originated in philosophical discussions, we show that it is testable and has received substantial empirical support.     

Same old, same old: the same-order representation theory of consciousness and the division of phenomenal labor

The same-order representation theory of consciousness holds that conscious mental states represent both the world and themselves. This complex representational structure is posited in part to avoid a powerful objection to the more traditional higher-order representation theory of consciousness. The objection contends that the higher-order theory fails to account for the intimate relationship that holds between conscious states and our awareness of them–the theory ‘divides the phenomenal labor’ in an illicit fashion. This ‘failure of intimacy’ is exposed by the possibility of misrepresentation by higher-order states. In this paper, I argue that despite appearances, the same-order theory fails to avoid the objection, and thus also has troubles with intimacy. A version of this paper was presented at the ‘Self-Representational Approaches to Consciousness’ conference, Center for Consciousness Studies, University of Arizona, March 18th–20th, 2005.     

Nonconscious perception, conscious awareness and attention

Because it is unclear how a nonconscious stimulus is cognitively processed, there is uncertainty concerning variables that modulate the processing. In this context recent findings of a set of neuroimaging experiments are important. These findings suggest that conscious and nonconscious stimuli activate same areas of the brain during performance of a similar task. Further, different areas are activated when a task is performed with or without awareness of processing. It appears that the neural network involved in cognitive processing depends on the awareness of processing rather than awareness of perception. Since conscious and nonconscious cognitive processing use separate neural networks, each processing is modulated by different variables. Attention modulates most conscious cognitive processing and most, but not all, nonconscious processing is attention dependent. Nonconscious tasks that require attentional resources, with or without conscious awareness, are processed using the attention dependent system. Further, because attention dependent and attention independent tasks are processed by separate neural networks, the cognitive processing and modulating variables can be understood better if cognitive tasks are defined as attention dependent or attention independent, rather than conscious or nonconscious.     

Volition and the idle cortex: beta oscillatory activity preceding planned and spontaneous movement

Prior to the initiation of spontaneous movement, evoked potentials can be seen to precede awareness of the impending movement by several hundreds of milliseconds, meaning that this recorded neural activity is the result of unconscious processing. This study investigates the neural representations of impending movement with and without awareness. Specifically, the relationship between awareness and 'idling' cortical oscillations in the beta range (18-24Hz) was assessed. It was found that, in situations where there was awareness of the impending movement, pre-movement evoked potentials were associated with a decrease in beta range oscillations. In contrast, when awareness of the impending movement was not present, the onset of the pre-movement potential was associated with tonic levels of beta range oscillations. A model is considered where by distributed neural activity remains outside of conscious awareness through the persistence of tonic slow wave cortical oscillations.     

Effortful control, explicit processing, and the regulation of human evolved predispositions

This article analyzes the effortful control of automatic processing related to social and emotional behavior, including control over evolved modules designed to solve problems of survival and reproduction that were recurrent over evolutionary time. The inputs to effortful control mechanisms include a wide range of nonrecurrent information--information resulting not from evolutionary regularities but from explicit appraisals of costs and benefits. Effortful control mechanisms are associated with the ventromedial prefrontal cortex and the ventral anterior cingulated cortex. These mechanisms are largely separate from mechanisms of cognitive control (termed executive function) and working memory, and they enable effortful control of behavior in the service of long range goals. Individual differences in effortful control are associated with measures of conscientiousness in the Five Factor Model of personality. Research in the areas of aggression, ethnocentrism, sexuality, reward seeking, and emotion regulation is reviewed indicating effortful control of automatic, implicit processing based on explicit appraisals of the context. Evidence is reviewed indicating that evolutionary pressure for cooperation may be a critical adaptive function accounting for the evolution of explicit processing.     

Integration without awareness: expanding the limits of unconscious processing

Human conscious awareness is commonly seen as the climax of evolution. However, what function-if any-it serves in human behavior is still debated. One of the leading suggestions is that the cardinal function of conscious awareness is to integrate numerous inputs-including the multitude of features and objects in a complex scene-across different levels of analysis into a unified, coherent, and meaningful perceptual experience. Here we demonstrate, however, that integration of objects with their background scenes can be achieved without awareness of either. We used a binocular rivalry technique known as continuous flash suppression to induce perceptual suppression in a group of human observers. Complex scenes that included incongruent objects escaped perceptual suppression faster than normal scenes did. We conclude that visual awareness is not needed for object-background integration or for processing the likelihood of an object to appear within a given semantic context, but may be needed for dealing with novel situations.     

Time, action, and consciousness

Time plays a central role in consciousness, at different levels and in different aspects of information processing. Subliminal perception experiments demonstrate that stimuli presented too briefly to enter conscious awareness are nevertheless processed to some extent. Implicit learning, implicit memory, and conditioning studies suggest that the extent to which memory traces are available for verbal report and for cognitive control is likewise dependent on the time available for processing during acquisition. Differences in the time available for processing also determine not only the extent to which one becomes conscious of action, but also provides the basis for making attributions of authorship to experienced acts. In this paper, we offer a brief overview of these different findings and suggest that they can all be understood based on the fact that consciousness takes time. From this perspective, the availability of representations to conscious awareness depends on the quality of these representations - the extent to which they are strong, stable in time, and distinctive. High-quality representations occur when processes of global competition have had sufficient time to operate so as to make the system settle into the best possible interpretation of the input. Such processes implement global constraint satisfaction and critically depend on reentrant processing, through which representations can be further enriched by high-level constraints. We discuss these ideas in light of current theories of consciousness, emphasizing the fact that consciousness should be viewed as a process rather than as a static property associated with some states and not with others.     

Developmental aspects of consciousness: how much theory of mind do you need to be consciously aware?

When do children become consciously aware of events in the world? Five possible strategies are considered for their usefulness in determining the age in question. Three of these strategies ask when children show signs of engaging in activities for which conscious awareness seems necessary in adults (verbal communication, executive control, explicit memory), and two of the strategies consider when children have the ability to have the minimal form of higher-order thought necessary for access consciousness and phenomenal consciousness, respectively. The tentative answer to the guiding question is that children become consciously aware between 12 and 15 months (+/-3 months).     

Accounting for Consciousness: Epistemic and Operational Issues

Within the philosophy of mind, consciousness is currently understood as the expression of one or other cognitive modality, either intentionality (representation per se), transparency (immediacy of cognitive content consequent upon the unawareness of underlying representational processes), subjectivity (first-person perspective) or reflexivity (autonoetic awareness). However, neither intentionality, subjectivity nor transparency adequately distinguishes conscious from nonconscious cognition. Consequently, the only genuine index or defining characteristic of consciousness is reflexivity, the capacity for autonoetic or self-referring, self-monitoring awareness. But the identification of reflexivity as the principal index of consciousness raises a major challenge in relation to the cognitive mechanism responsible for operationalizing such a reflexive state. Current reliance by higher-order and intrinsic self-representational theories on self-representing data structures to achieve reflexive self-awareness is highly problematic, suggesting a solution in terms of a self-referential processing regime.     

Mediators of age-related differences in recollective experience in recognition memory

This study examined states of awareness with the Remember/Know paradigm during verbal recognition memory in young and old adults. Following the presentation of a word list, subjects undertook a recognition test and indicated whether they could consciously recollect its prior occurrence (R) or recognize it on some other basis, without conscious recollection (K). In this individual-difference approach we also incorporated various processing-speed and working-memory measures to study the link between aging, states of awareness and processing resources. The results revealed that, compared to younger adults, older adults exhibited a decline in the amount of R responses during the recognition test whereas the amount of K responses did not change. Structural equation modeling indicated that a slower processing speed associated with a limited working-memory capacity is a key to explaining age-related variance in conscious recollection. The findings offer further support for the distinction between remembering and knowing and for the processing-resources hypothesis of aging.     

On being, knowing and having a self

This paper(1) takes the distinction between being conscious ('core consciousness') and knowing that one is conscious (self-reflexive consciousness) as a starting point for differentiating between three different aspects of the self: 1) the overall process of psychosomatic being which we share with all living creatures and which expresses itself through action (self as totality), 2) the conscious awareness of knowing the self that is a peculiarly human phenomenon consequent on the development of symbolic imagination (sense of self including numinous experiences of the self) and 3) having a self (or soul) as an essential attribute of being human that can only be achieved through being endowed with a self in the mind of others (self-identity leading to the self as the centre of the personality). Some clinical implications of these distinctions are considered including the role of interpretation as fostering integration through the provision of alternative self-images, the loss of self-reflexive consciousness in states of overwhelming affect and the attack on the spontaneous psychosomatic being of the self in states of self-hatred and self-division.     

Information processing during sleep onset and sleep.

This Special Section examines the extent of information processing during sleep onset and sleep itself. It is generally agreed that, stimulus input is markedly inhibited during sleep, thus preventing conscious awareness of the external environment. Overt behavioural responses are rarely made within sleep. Two neurophysiological measures are therefore often used. The electrical activity of the brain (the EEG) can be employed to distinguish waking (conscious) from sleeping (unconscious) states. It is also possible to quantify the EEG prior to and following a detection (or a failure of a detection) of a stimulus. Such measures can thus be used to predict conscious awareness. A second measure that frequently has been employed is the brain's response to an external stimulus (the evoked potential). Different components of the evoked potential can be used to trace the extent of information processing during the different states of consciousness. Some are associated with a preconscious detection while others are associated with conscious awareness. Other evoked potentials may be unique to sleep.     

An information processing analysis of mental multiplication

The specific model of central or conscious processing system (CPS) is presented. It consists of two part: (1) a number of information carrying registers, and (2) a functional unit controlling the processes performed on the contents of the registers. The capacity limit is explained as a combination of storage capacity and processing capacity. The capacity limit was estimated by an experiment using mental multiplication performed according to a particular algorithm. The results suggested that the capacity was around eight to nine registers when the algorithm was strictly followed; this limit could, however, be exceeded because some problems automatically were coded and remembered by rules rather then by rehearsal. The results further suggested that information processing, i.e. the multiplication, had to take place on a time-sharing basis in competition with rehearsal, thus suggesting the existence of higher-order control system.     

Conscious and unconscious thought in artificial grammar learning

Unconscious Thought Theory posits that a period of distraction after information acquisition leads to unconscious processing which enhances decision making relative to conscious deliberation or immediate choice (Dijksterhuis, 2004). Support thus far has been mixed. In the present study, artificial grammar learning was used in order to produce measurable amounts of conscious and unconscious knowledge. Intermediate phases were introduced between training and testing. Participants engaged in conscious deliberation of grammar rules, were distracted for the same period of time, or progressed immediately from training to testing. No differences in accuracy were found between intermediate phase groups acting on decisions made with meta-cognitive awareness (either feeling-based intuitive responding or conscious rule- or recollection-based responding). However, the accuracy of guess responses was significantly higher after distraction relative to immediate progression or conscious deliberation. The results suggest any beneficial effects of 'unconscious thought' may not always transfer to conscious awareness.     

The neural, evolutionary, developmental, and bodily basis of metaphor

We propose that there are four fundamental kinds of metaphor that are uniquely mapped onto specific brain “networks” and present preliterate (i.e., evolutionary, including before the appearance of written language in the historical record), prelinguistic (i.e., developmental, before the appearance of speech in human development), and extralinguistic (i.e., neuropsychological, cognitive) evidence supportive of this view. We contend that these basic metaphors are largely nonconceptual and entail (a) perceptual-perceptual, (b) cross-modal, (c) movement-movement, and (d) perceptual-affective mappings that, at least, in the initial stages of processing may operate largely outside of conscious awareness. In opposition to our basic metaphor theory (B_mT), the standard theory (S_mT) maintains that metaphor is a conceptual mapping from some base domain to some target domain and/or represents class-inclusion (categorical) assertions. The S_mT captures aspects of secondary or conceptual metaphoric relations but not primary or basic metaphoric relations in our view. We believe our theory (B_mT) explains more about how people actually recognize or create metaphoric associations across disparate domains of experience partly because they are “pre-wired” to make these links.     

Disambiguating conscious and unconscious influences: do exclusion paradigms demonstrate unconscious perception?

Does exclusion failure--responding with previously presented words despite instructions to avoid doing so--demonstrate unconscious influences? This article examines exclusion-based evidence for unconscious perception. I propose an alternative signal detection theory (SDT) framework that can account for exclusion failure and ostensibly convergent qualitative differences without positing additional unconscious perceptual mechanisms. In the proposed SDT model, exclusion failure is a criterion artifact, similar to classic SDT-based critiques of subjective threshold approaches. However, it is suggested that exclusion approaches do demonstrate that response strategies are applied only to above-criterion stimuli and thereby illustrate important qualitative differences between two conscious processes: phenomenal awareness itself and higher-order (i.e., metacognitive) decision processes.     

More thoughts on the unconscious: reply to Brody and to Lewicki and Hill

Brody (1989) and Lewicki and Hill (1989) present commentaries on my central thesis (Reber, 1989) that there exist powerful induction routines that operate largely independently of awareness and yield rich and complex tacit knowledge that resists attempts to make it conscious, although these commentaries are of dramatically different kinds. Because there is a fairly clear basis of agreement between Lewicki and Hill and the points that I made, this reply deals almost entirely with the issues raised by Brody. The focus is on two classes of issues: (a) those of a methodological nature that surround the general problem of doing experiments on unconscious cognition and (b) those that derive from considerations of evolutionary biology that provide a basis for arguing that implicit operations are primary and form the foundation for conscious processes.     

Gender differences in implicit and explicit processing of emotional facial expressions as revealed by event-related theta synchronization

Emotion information processing may occur in 2 modes that are differently represented in conscious awareness. Fast online processing involves coarse-grained analysis of salient features and is not represented in conscious awareness; offline processing takes hundreds of milliseconds to generate fine-grained analysis and is represented in conscious awareness. These processing modes may be studied using event-related electroencephalogram theta synchronization as a marker of emotion processing. Two experiments were conducted that differed on the mode of emotional information presentation. In the explicit mode, subjects were explicitly instructed to evaluate the emotional content of presented stimuli; in the implicit mode, their attention was directed to other features of the stimulus. In the implicit mode, theta synchronization was most pronounced in the early processing stage, whereas in the explicit mode, it was more pronounced in the late processing stage. The early processing stage was more pronounced in men, whereas the late processing stage was more pronounced in women. Implications of these gender differences in emotion processing for well-documented differences in social behavior are discussed.     

Temporal binding and the neural correlates of sensory awareness

Theories of binding have recently come into the focus of the consciousness debate. In this review, we discuss the potential relevance of temporal binding mechanisms for sensory awareness. Specifically, we suggest that neural synchrony with a precision in the millisecond range may be crucial for conscious processing, and may be involved in arousal, perceptual integration, attentional selection and working memory. Recent evidence from both animal and human studies demonstrates that specific changes in neuronal synchrony occur during all of these processes and that they are distinguished by the emergence of fast oscillations with frequencies in the gamma-range.     

Inhibitory control as a moderator of threat-related interference biases in social anxiety

This research examines control over the effect of arousal, a dimension of affect, on judgement. Past research shows that high processing motivation enhances control over the effects of affect on judgement. Isolating and studying arousal as opposed to valence, the other dimension of affect, and its effect on judgement, we identify boundary conditions for past findings. Drawing from the literature on processes by which arousal influences judgement, we demonstrate that the role of motivation is contingent upon the type of judgement task (i.e., memory- versus stimulus-based judgement). In stimulus-based judgement, individuals exert greater control over the effect of arousal on judgement under low compared to high motivation. In contrast, in memory-based judgement individuals exert greater control over the effect of arousal under high compared to low motivation. Theoretical implications and avenues for future research are discussed.