Opinion
How rich is consciousness? The partial awareness hypothesis

https://doi.org/10.1016/j.tics.2010.04.006Get rights and content

Current theories of consciousness posit a dissociation between ‘phenomenal’ consciousness (rich) and ‘access’ consciousness (limited). Here, we argue that the empirical evidence for phenomenal consciousness without access is equivocal, resulting either from a confusion between phenomenal and unconscious contents, or from an impression of phenomenally rich experiences arising from illusory contents. We propose a refined account of access that relies on a hierarchy of representational levels and on the notion of partial awareness, whereby lower and higher levels are accessed independently. Reframing of the issue of dissociable forms of consciousness into dissociable levels of access provides a more parsimonious account of the existing evidence. In addition, the rich phenomenology illusion can be studied and described in terms of testable cognitive mechanisms.

Section snippets

One or two types of consciousness?

Understanding the psychological and neurobiological determinants of consciousness constitutes a major challenge in contemporary science 1, 2. Following a long period of neglect, the study of consciousness has gained respect by acknowledging the importance of data collection, empirical support, and all of the core principles of scientific investigation. This research field now offers functional descriptions and testable predictions regarding conscious processing 3, 4, 5, 6, 7.

However, critics of

The arguments: phenomenal overflow and neural purity

Two main empirical arguments, the overflow argument and the purity argument, have been offered by proponents of the access–phenomenal consciousness dissociation. The overflow argument is rooted in the intuition that we are conscious of much more than we can describe and manipulate. For instance, when observing a complex visual scene, we feel that we have a rich visual experience even if we can report only a few elements. This phenomenon was operationalized in Sperling's now famous study over

The limits: paradoxes and circularities

Here we assert that arguments favoring dissociative approaches to consciousness suffer from serious flaws, as previously argued in the context of higher-order theories [16] and workspace theories [17] of consciousness. Our counter-arguments center on the fact that the phenomenal overflow argument is confounded with partial awareness situations, whereas the neural purity argument reflects the confusion between phenomenal consciousness and unconscious perception. We start with the overflow

Basic assumptions: a hierarchical view of conscious access

Much discussion has centered on the definition of phenomenal consciousness while assuming that access consciousness poses no difficulty. We believe, however, that some of the problems raised above actually stem from an ill-defined view of access mechanisms and a lack of consideration for the possibility of partial awareness. Here, we adopt the standard definition of access consciousness, according to which a mental content is conscious if it is broadcast to cognitive subsystems, notably working

Reinterpretation of empirical arguments

In light of the assumptions described above, we propose that the empirical arguments for inaccessible consciousness correspond either to situations of complete unawareness, in the case of neural purity, or to situations of partial awareness, in the case of the overflow argument. Complete unawareness occurs in paradigms such as attentional blink, inattentional blindness, or extinction in neglect patients, where subjects confidently report that they have not seen anything. In other words,

Additional assumptions: exploring the illusion of phenomenal richness

Although the basic assumptions presented above constitute the core of our hypothesis, they primarily account for how the signal is accessed at each level of representation. However, when subjects fail to accurately report items at one level (e.g. letters), they might still claim that they see all the letters. A number of additional assumptions, although tentative, are necessary to account for the illusion of phenomenal richness in functional terms. First, access at each level comes with a

Continuous vs. all-or-none conscious access

Before concluding, we would like to point out that the partial awareness hypothesis might also offer a parsimonious solution to the controversy about whether consciousness is an all-or-none or graded phenomenon 24, 27, 28, 29. Indeed, by incorporating the notion of independently accessible levels of representation, we can attain a graded perspective on conscious experience even with the all-or-none mechanisms for access proposed in workspace theories 3, 27 (Box 1). Indeed, although

Concluding remarks and future directions

Several aspects of the preliminary proposal presented here remain speculative and require further specification, particularly regarding the exact interplay between prior information, confidence and signal processing, as well as the interaction between levels of representation. Although extended discussion is beyond the scope of the present article, many of these interactions (i.e. between signal and prior information, between levels of representations) can be construed in terms of Bayesian

References (51)

  • A.K. Seth

    Measuring consciousness: relating behavioural and neurophysiological approaches

    Trends Cogn. Sci.

    (2008)
  • M. Overgaard

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

    Conscious Cogn.

    (2006)
  • Z. Dienes et al.

    Gambling on the unconscious: a comparison of wagering and confidence ratings as measures of awareness in an artificial grammar task

    Conscious. Cogn.

    (2010)
  • K.P. Kording et al.

    Bayesian decision theory in sensorimotor control

    Trends Cogn. Sci.

    (2006)
  • N. Block

    Two neural correlates of consciousness

    Trends Cogn. Sci.

    (2005)
  • S. Zeki et al.

    Toward a theory of visual consciousness

    Conscious. Cogn.

    (1999)
  • V.A. Lamme

    Why visual attention and awareness are different

    Trends Cogn. Sci.

    (2003)
  • C. Summerfield et al.

    Expectation (and attention) in visual cognition

    Trends Cogn. Sci.

    (2009)
  • A. Kleinschmidt

    The neural structures expressing perceptual hysteresis in visual letter recognition

    Neuron

    (2002)
  • C. Koch et al.

    Attention and consciousness: two distinct brain processes

    Trends Cogn. Sci.

    (2007)
  • J. Prinz

    A neurofunctional theory of visual consciousness

    Conscious. Cogn.

    (2000)
  • L. Reddy et al.

    Face identification in the near-absence of focal attention

    Vision Res.

    (2006)
  • A. Treisman et al.

    A feature-integration theory of attention

    Cogn. Psychol.

    (1980)
  • C. Koch

    The Quest for Consciousness: A Neurobiological Approach

    (2004)
  • B.J. Baars

    A Cognitive Theory of Consciousness

    (1989)
  • Cited by (276)

    • How to get rich from inflation

      2024, Consciousness and Cognition
    • Time marking in perception

      2023, Neuroscience and Biobehavioral Reviews
    View all citing articles on Scopus
    View full text