Chapter
Six
The unity
unified first and then somehow ‘enters consciousness’. What this means remains
unexplained.
Proceeding from the ‘close relation between consciousness and binding’, Singer
suggests that ‘only those results of the numerous computational processes
that have been bound successfully will enter consciousness simultaneously’ (in
Metzinger, 2009, p. 67). Although ‘entering consciousness’ sounds like magic, he
explains that consciousness does not depend on any particular group of neurons
but is ‘an emergent property of a particular dynamical state of the distributed
cortical network’. Yet he does not explain how this emergence works, nor what it
means for subjectivity to emerge from the temporal coherence of a large popula-
tion of distributed neurons.
MICRO-CONSCIOUSNESSES
The very concept of the unity of consciousness is questioned by British neurobi-
ologist Semir Zeki, who proposes instead that there are as many micro-conscious-
nesses as processing nodes in a system. He is not referring to cases of multiple
personality or split brains (considered later in this chapter), but claiming that
a multiplicity of consciousnesses is the norm: the unification that comes with
self-consciousness is an exception made possible only by language.
Zeki (2001, 2007) notes that the many parallel systems of the primate visual system
reach their perceptual endpoints at different times. For example, the attributes of
an object, such as orientation, depth, facial expression, or shape, are processed
separately, and colour (processed in V4 and V4α) may be as much as 80 ms ahead
of motion (processed in V5) (Zeki and Bartels, 1999). But we are not aware of this
perceptual asynchrony. In Zeki’s view, each of these separate cortical systems has
its own conscious correlate.
Cortical and subcortical systems both consist of many hierarchically organised
nodes with multiple inputs, outputs, and connections, and since no node is a
recipient only, ‘there is no terminal station in the cortex’ (Zeki, 2001, pp. 60–61),
‘no final integrator station in the brain’ (Zeki and Bartels, 1999, p. 225), no ‘pon-
tifical neuron’ (James, 1890). There is no need for micro-consciousnesses to ‘be
reported to a “center” for consciousness, or a “Cartesian Theater” ’ (Zeki, 2001, p.
69). ‘Visual consciousness is therefore distributed in both space and time’ (p. 57).
Experiments inspired by Mondrian’s abstract artworks show that basic colour
perception can occur without the activation of the frontal lobes (Zeki and Marini,
1998), which implies phenomenal consciousness without higher processing.
Conversely, in patients with lesions that cut off input from primary visual cortex,
activity in certain cells of V5 (which plays a major role in motion perception)
can correlate with ‘a crude but conscious experience’ (Zeki, 2015, p. 12) of fast
high-contrast movement. This indicates that active participation by V1 is not
required for visual consciousness, as had long been believed.
Because micro-consciousnesses are distributed in both space and time, and
because binding of different attributes takes different lengths of time, Zeki argues
that binding is a post-conscious phenomenon (Zeki and Bartels 1998, 1999; Zeki,
2007). In other words, there is phenomenal consciousness of visual attributes
before those attributes are bound. This sets Zeki apart from Crick and Koch (1990;
‘only those results
[. . .] that have been
bound successfully will
enter consciousness
simultaneously’(Singer, in Metzinger, 2009, p. 67)‘binding is a post-
conscious phenomenon’(Zeki, 2007, p. 584)