Levels of Consciousness / Visual Bandwidth

Two brief notes…

Tim Bayne, Jakob Hohwy, and Adrian M. Owen, ‘Are There Levels of Consciousness?’, Trends in Cognitive Sciences, 20 (2016), 405-13.

This aims to make an intervention in the science of consciousness. It observes a tendency towards a one-dimensional approach, wherein different states are analysed holistically as examples of different points of one scale, high to low. There is some kind of line from coma to conscious wakefulness, but there are other states that don’t fit: REM sleep, sleep-walking, vegetative states. Sleep and sedation have crucial differences. Bayne et al. draw attention to the problem and suggest that we should think in terms of ‘multidimensional space’ rather than levels. Not surprisingly I think that literature affords examples of diverse mental states, including ones not accounted for in their taxonomy. Hermione in The Winter’s Tale, not for the first time, is an example of an unanticipated mind-state that may nevertheless open up special dimensions. The awakening statue, or perhaps, the Queen who, though never a statue, has nevertheless somehow passed sixteen years in a somewhat suspended state: these are categories that enrich the picture of the problem, or the problem of the picture. It might seem an odd way to test attempts to provide a convenient taxonomy of consciousness, but there must be a role for the imagination somewhere in the process, given that the issues obviously aren’t amenable to any simplistic approach.


Michael A. Cohen, Daniel C. Dennett, and Nancy Kanwisher, ‘What is the Bandwidth of Perceptual Experience?’, Trends in Cognitive Sciences, 20 (2016), 324-35

The idea here is that although we think we see the world in rich detail, experiments suggest that ‘the amount of visual information observers can perceive and remember at any given moment is limited’. Cohen et al. are interested in the mismatch between subjective impressions and objective observations. Perhaps consciousness does more, or better, than the perceptual tests allow. Their view is that ‘although we see more than the handful of objects claimed by prominent models of visual attention and working memory, we still see far less than we think we do’. With the help of some simple but effective blurry pictures, they build an argument that ‘a handful of items are perceived with high fidelity, while the remainder of the world is represented as an ensemble statistic (or set of statistics)’. In their view, the interesting thing for consciousness research is ‘the nature of the visual information that is captured beyond the few high-fidelity objects that can be held in visual working memory’. It might be interesting to think about how literary descriptions test out some of the boundaries. Are there ways in which they are over-photographic, subjectively inflected, or manifestly partial and blurry? Obviously this is an issue in visual art as well, but the thing about verbal description is that understanding its perspective, its process, what’s gained and what’s lost, takes a certain sort of work that gives us chances to turn back and think ‘is this what it’s like?’.

E-mail me at rtrl100[at]cam.ac.uk

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