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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Why Arti cial Consciousness Matters?</article-title>
      </title-group>
      <contrib-group>
        <aff id="aff0">
          <label>0</label>
          <institution>Imperial College London Leverhulme Centre for the Future of Intelligence</institution>
        </aff>
      </contrib-group>
      <abstract>
        <p>In this paper I outline the case for arti cial consciousness research which, while rising in popularity, remains less impactful than work in neighbouring elds. I argue that the ethical concerns around creating arti cial consciousness are important, even with respect to near-future incremental advances towards general intelligence. I also give examples of how AI consciousness in particular provides unique tools and methods for testing and thinking about theories of consciousness from both metaphysical and practical standpoints.</p>
      </abstract>
      <kwd-group>
        <kwd>Arti cial Consciousness</kwd>
        <kwd>Phenomenal Consciousness</kwd>
        <kwd>Ethics</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>Introduction</title>
      <p>
        While consciousness research has progressed rapidly in recent years, scienti c
consensus remains out of reach. Meanwhile, AI has made signi cant
advancements, reaching superhuman performance on a wide range of tasks. Humans are
no longer the best quiz-show contestants [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ], the best Go players [
        <xref ref-type="bibr" rid="ref18">18</xref>
        ], or even, in
some aspects, the best doctors [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ]. This rapid expansion, and Bostrom's in
uential discussion of mind crimes [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ], has led some arti cial consciousness research
to be framed partially [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ], or completely, in terms of superintelligence [
        <xref ref-type="bibr" rid="ref15 ref21">15, 21</xref>
        ].
      </p>
      <p>
        However, even with recent advances, no current state-of-the art AI approaches
can compete with simple animals when it comes to adapting to unexpected
changes to their environment or any of a wide range of behaviours commonly
associated with consciousness. Furthermore, when we attribute consciousness to
animals, it is generally accepted that human-like intelligence is not necessary.
The rst conscious AI systems are not likely to have surpassed the general
intelligence of humans, or even of many animals usually considered conscious [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ].
Understanding such systems of minimal arti cial consciousness presents
important ethical questions, and also opportunities to improve both our understanding
of AI and of our own consciousness.
      </p>
      <p>
        Whilst the amount of work on arti cial consciousness has been growing, the
area has yet to be as impactful as other elds in either consciousness or AI
[
        <xref ref-type="bibr" rid="ref13">13</xref>
        ]. This paper presents the case for the importance and timeliness of research
into arti cial consciousness without superintelligence. It is ethically relevant, it
can teach us about consciousness, and it can help us progress towards general
intelligence in AI.
      </p>
    </sec>
    <sec id="sec-2">
      <title>Phenomenal Consciousness</title>
      <p>
        For the purposes of this paper I will restrict discussion to phenomenal
consciousness. There is no agreed upon de nition. For our purposes I refer to
Schwitzgebel's extended de nition by example [
        <xref ref-type="bibr" rid="ref16">16</xref>
        ]. Positive examples include
your current visual experience of this text, the auditory experience of
surrounding sounds, any imagery you choose to conjure into the mind, and the felt sense
of emotions. Negative examples include your current visual experience of the
other side of the world, currently unrecalled knowledge (such as that Paris is
the capital of France), and the ow of blood in the capillaries of your left knee.
Phenomenal consciousness is then de ned as the simplest thing common to all
the positive examples and missing from all negative ones. While there are
technically an in nite number of concepts (and combinations of concepts) that t
this de nition, the intended interpretation is assumed to be clear enough.
      </p>
      <p>
        There are many proposed tests for machine consciousness, most of which
ignore the phenomenological component, instead focusing on more measurable
related aspects [
        <xref ref-type="bibr" rid="ref13">13</xref>
        ]. However, ignoring the phenomenological component amounts
to ignoring the reason that consciousness is interesting in the rst place, and the
thing that sets it apart from general measures of intelligence. The problem of
how phsyical systems can give rise to phenomenal experiences at all, the `hard
problem' of consciousness, must be addressed, even if only to be explained away,
by any complete theory of arti cial consciousness [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ]. For the purposes of this
paper I will assume consciousness means phenomenal consciousness and
maintain the commonly held assumptions that consciousness supervenes on purely
physical processes and there are many physical substrates that could realise it.
3
      </p>
    </sec>
    <sec id="sec-3">
      <title>The case for arti cial consciousness</title>
      <p>This section is split into two parts. The rst part concerns the ethical
considerations around introducing potentially conscious entities to the world. I argue that
discussion should be focused on near-term possibilities of minimal consciousness.
The second part gives examples of the unique methodologies and insights about
consciousness a orded by research into arti cial intelligence.
3.1</p>
      <sec id="sec-3-1">
        <title>The ethical case</title>
        <p>
          There is no de nitive answer to which animals are conscious. At one end of the
scale, panpsychists ascribe consciousness to all animals (and beyond) [
          <xref ref-type="bibr" rid="ref4">4</xref>
          ]. At the
other extreme some higher-order thought theorists deny consciousness to most
non-human animals, though even here there is large disagreement [
          <xref ref-type="bibr" rid="ref14">14</xref>
          ]. Most
views sit somewhere in the middle, claiming human-like and more intelligent
animals are conscious whilst other `lesser' animals are not. For example,
Peter Godfrey-Smith suggests mammals, birds, squids and octopods as candidates
whilst other mollusks, jelly sh, and many sh are not [
          <xref ref-type="bibr" rid="ref9">9</xref>
          ]. Categorising animals
by consciousness is made even harder under the common view that consciousness
exists on a gradual scale, whereby ascriptions on a per-animal basis are more
involved than a simple `yes' or `no' answer.
        </p>
        <p>While there is wide disagreement in ascriptions of consciousness, there is one
thing common to all the above; superintelligence is not required. The human
case by itself is enough to prove this. The majority of theories go much further,
ascribing consciousness to entities with rudimentary - or even in some cases,
no - intelligence. Extrapolating to arti cial consciousness, it may be possible to
recreate consciousness in minimally intelligent arti cial systems.</p>
        <p>Furthermore, it is likely that we will create minimally intelligent conscious
systems long before we create entities that have, or exceed, human-like
intelligence. As AI progress incrementally towards its goal, the question of AI
consciousness will arise for, at least in the biological sense, minimally intelligent
systems long before it does for superintelligent systems. Measured on aspects
of intelligence common in biologocial systems, the rst ever conscious arti cial
system will likely be closer to a mouse than a superhuman.</p>
        <p>
          Thomnas Metzinger has put forward a thought-experiment in which he
suggests that the rst conscious AI systems would nd themselves in a situation
similar to that of human infants with cognitive and emotional de cits [
          <xref ref-type="bibr" rid="ref12">12</xref>
          ]. The
idea is that if any AI systems are ever conscious, the rst set of conscious entities
will be the least capable that we can create. As with any engineering project, the
rst few attempts will be less streamlined and capable than future versions. In
comparison to our consciousness, they will be both cognitively and emotionally
de cient, which leads to obvious concerns about su ering.
        </p>
        <p>
          I take the general case for the importance of ethical considerations towards
any conscious entities with the capacity for capacity for su ering to be
uncontroversial [
          <xref ref-type="bibr" rid="ref19">19</xref>
          ]. Should it be possible to create entities that su er, then they will
naturally have moral patiency. The real question is whether or not we will ever
have even minimal arti cial consciousness and, even if yes, whether it will be of
a form with the capacity to su er. Sotala et al specify three general rules for a
problem to be worth considering (paraphrased below) [
          <xref ref-type="bibr" rid="ref21">21</xref>
          ]. They apply these to
the superintelligence case, but the rules by themselves are also applicable here:
1. The outcome must cause enough harm to merit attention.
2. The outcome must have reasonable probability of being realised.
3. There must be some way to reduce either 1. or 2.
        </p>
        <p>If it can be shown that just one of these conditions is violated then a problem
becomes much less pressing. However, for the case of minimally conscious AI, I
will argue that all of these hold.</p>
        <p>The scale at which AI systems can be created or destroyed suggests the
problem is `bad enough'. Should it be possible to create a conscious arti cial
entity, then its arti cial nature will allow for easy copying and replicating. Many
modern AI algorithms involve creating multiple instantiations and then testing
them over a wide range of domains. This practice means that any created AI
consciousness would probably exist many times over, multiplying the ethical
signi cance of the event.</p>
        <p>
          Whether or not even minimal arti cial consciousness has a reasonable
probability of being realised is still open to debate. However, there are many reasons
to believe this will happen at some point and AI research is making incremental
progress in this direction. Given the ubiquitous nature of biological consciousness
and the progress of cognitively inspired AI [
          <xref ref-type="bibr" rid="ref10 ref11">10, 11</xref>
          ], it is premature to rule out
the possibility of arti cial consciousness, especially accidentally or unknowingly.
        </p>
        <p>Finally, there must be some way to reduce the probability of causing harm
or the amount of harm caused. As our understanding of consciousness grows,
our ability to in uence its creation also grows. If we do develop a better
understanding of which systems are conscious, this could be used to, in the extreme
case, avoid creating such systems in the rst place.</p>
        <p>Arti cial consciousness research reasonably meets all three of the criteria,
but, more importantly, the criteria are useful for shaping the most important
areas of research. The most ethically abhorrent scenario is that arti cial
consciousness research lags behind AI progress and we only nd out too late that
we have been creating conscious, su ering AI systems. This makes the topic not
only ethically relevant, but urgent. Our understanding of consciousness must
keep pace with, and be applied to, progress in AI.
3.2</p>
      </sec>
      <sec id="sec-3-2">
        <title>Learning about consciousness from AI</title>
        <p>Beyond the ethical considerations, AI is uniquely placed to teach us about
consciousness. It can be a testbed for theories, and also provide insights into
longstanding metaphysical problems.</p>
        <p>
          The Roomba Test One use from considering theories of consciousness
applicable to AI systems is that they can be evaluated through minimal instantiations.
Any substrate independent theory of consciousness has to answer to its simplest
possible implementation in AI, and often that implementation will provide
insights into what is working and what is missing from the theory. I have called this
the Roomba Test because this well-known device features in public discourse on
machine consciousness [
          <xref ref-type="bibr" rid="ref20">20</xref>
          ] due to meeting some rudimentary properties related
to consciousness; autonomy and representations of the world. At its simplest this
test can be just a thought experiment where it serves as a sanity check on theories
of consciousness. However, actual implementations provide much more feedback
and can then be further compared against preferred measures of consciousness.
        </p>
        <p>
          One response to Roomba examples is to bite the bullet, such as IIT does
[
          <xref ref-type="bibr" rid="ref22">22</xref>
          ] when faced with similar questions about systems that, unlike the Roomba,
would have non-zero consciousness (i.e. &gt; 0) [
          <xref ref-type="bibr" rid="ref17">17</xref>
          ]. The theory predicts that a
small set of interconnected logic gates is conscious, and, in the face of such a
system, sticks to this claim. Another response is to use such examples to re ne
the theory and move towards a better understanding as is the dialectical method
in the presentation of the radical plasticity thesis [
          <xref ref-type="bibr" rid="ref6">6</xref>
          ]. If there exists no simplest
instantiation of an arti cial system then this stands as a critique of the generality
of the theory. Either way, AI provides an important tool for evaluating the claims
of theories of consciousness.
The Veridical Dualist Most of modern day AI research uses simulated
environments for testing due to their many advantages over real-world, or static,
data sets. Simulated environments can be constrained to test for exactly the
problem that is being searched, noise can be controlled, they can be simpli ed
as necessary, mistakes don't have real-world consequences, and they are cheap
to copy and run. Algorithms can be swapped in and out and are usually run in a
separate thread (and often using completely di erent programming languages)
to the simulated environments themselves. With all these advantages, and the
recent proliferation and improvement of such environments it is likely that more
and more systems will be tested in this way in the future.
        </p>
        <p>
          The veridical dualist thought experiment, (originally from Chalmers [
          <xref ref-type="bibr" rid="ref3">3</xref>
          ]),
asks you to imagine you are an arti cial entity, existing in a rich simulated
environment. Furthermore, you happen to be conscious and even capable of
asking (and solving) questions about your consciousness. You have learnt much
about your simulated world by exploring it and probing it, paying close attention
to how it reacts and moves. All this information becomes integrated into your
experience of the simulated environment. However, it occurs to you that the
thoughts and experiences you have don't seem to originate from within this
world. They seem (comparitively) ethereal. They seem to come from somewhere
else, perhaps they are some kind of secondary metaphysical type to everything
else in your (unbeknownst to you) simulated environment.
        </p>
        <p>A simulated entity might naturally become an ontological dualist. No
matter how hard the arti cial entity looks for the underlying substrate forming its
experiences inside its world, it will never be able to nd them. Its equivalent
of a brain is running in a computer in our world and, presumably, giving rise
to conscious experiences that, from its perspectives, exist in the only world it
knows, the simulated one. It seems rational for it to become a dualist and, from
the perspective of its simulated world, correct to do so.</p>
        <p>What this thought experiment, and the host of others that can be created
by considering the unique properties of simulated environments, tell us about
our own situation is not yet clear. This certainly does not mean we should all be
dualists, but, as Chalmers put it, perhaps \dualism isn't quite so outlandish and
conceptually problematic as tends to be supposed." The important point here
is that AI consciousness provides some unique perspectives for advancing our
understanding and will continue to be fruitful on this front as we come closer
to realising complex simulated worlds and able to implement more complicated
theories of consciousness.
4</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>Conclusion</title>
      <p>In summary, there are many reasons to expect that AI will play an important
role in our future understanding of consciousness. Furthermore, understanding
arti cial consciousness is an ethically relevant problem on a scale only limited
by our increasing computational resources. It will be important in the future
that advances in consciousness science are translated and incorporated into our
understanding of arti cial consciousness. It will also be important that, in the
other direction, advances in AI are translated back to consciousness science, not
least, to ensure that if we ever do create arti cial consciousness, we have at least
some idea of what we are doing.</p>
    </sec>
  </body>
  <back>
    <ref-list>
      <ref id="ref1">
        <mixed-citation>
          1.
          <string-name>
            <surname>Arrabales</surname>
            ,
            <given-names>R.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Ledezma</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Sanchis</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          :
          <article-title>Consscale: A pragmatic scale for measuring the level of consciousness in arti cial agents</article-title>
          .
          <source>Journal of Consciousness Studies</source>
          <volume>17</volume>
          (
          <issue>3-4</issue>
          ),
          <volume>131</volume>
          {
          <fpage>164</fpage>
          (
          <year>2010</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref2">
        <mixed-citation>
          2.
          <string-name>
            <surname>Bostrom</surname>
          </string-name>
          , N.:
          <article-title>Superintelligence: paths, dangers, strategies</article-title>
          . Oxford University Press Oxford (
          <year>2014</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref3">
        <mixed-citation>
          3.
          <string-name>
            <surname>Chalmers</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          :
          <article-title>How cartesian dualism might have been true</article-title>
          . http://consc.net/notes/dualism.html, accessed:
          <fpage>2018</fpage>
          -11-01
        </mixed-citation>
      </ref>
      <ref id="ref4">
        <mixed-citation>
          4.
          <string-name>
            <surname>Chalmers</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          :
          <article-title>Panpsychism and panprotopsychism</article-title>
          .
          <source>Consciousness in the physical world: Perspectives on Russellian monism 246</source>
          (
          <year>2015</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref5">
        <mixed-citation>
          5.
          <string-name>
            <surname>Chalmers</surname>
            ,
            <given-names>D.J.:</given-names>
          </string-name>
          <article-title>Facing up to the problem of consciousness</article-title>
          .
          <source>Journal of consciousness studies 2</source>
          (
          <issue>3</issue>
          ),
          <volume>200</volume>
          {
          <fpage>219</fpage>
          (
          <year>1995</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref6">
        <mixed-citation>
          6.
          <string-name>
            <surname>Cleeremans</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          :
          <article-title>Consciousness: the radical plasticity thesis</article-title>
          .
          <source>Progress in brain research 168</source>
          ,
          <volume>19</volume>
          {
          <fpage>33</fpage>
          (
          <year>2007</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref7">
        <mixed-citation>
          7.
          <string-name>
            <surname>Fauw</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          , et al.:
          <article-title>Clinically applicable deep learning for diagnosis and referral in retinal disease</article-title>
          .
          <source>Nature medicine 24(9)</source>
          ,
          <volume>1342</volume>
          (
          <year>2018</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref8">
        <mixed-citation>
          8.
          <string-name>
            <surname>Ferrucci</surname>
          </string-name>
          , et al.:
          <article-title>Building watson: An overview of the deepqa project</article-title>
          .
          <source>AI</source>
          magazine
          <volume>31</volume>
          (
          <issue>3</issue>
          ),
          <volume>59</volume>
          {
          <fpage>79</fpage>
          (
          <year>2010</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref9">
        <mixed-citation>
          9.
          <string-name>
            <surname>Godfrey-Smith</surname>
            ,
            <given-names>P.</given-names>
          </string-name>
          :
          <article-title>Other minds: The octopus, the sea, and the deep origins of consciousness</article-title>
          . Farrar, Straus and Giroux (
          <year>2016</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref10">
        <mixed-citation>
          10.
          <string-name>
            <surname>Hassabis</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Kumaran</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          , Summer eld, C.,
          <string-name>
            <surname>Botvinick</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          :
          <article-title>Neuroscience-inspired arti cial intelligence</article-title>
          .
          <source>Neuron</source>
          <volume>95</volume>
          (
          <issue>2</issue>
          ),
          <volume>245</volume>
          {
          <fpage>258</fpage>
          (
          <year>2017</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref11">
        <mixed-citation>
          11.
          <string-name>
            <surname>Lake</surname>
            ,
            <given-names>B.M.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Ullman</surname>
          </string-name>
          , T.D.,
          <string-name>
            <surname>Tenenbaum</surname>
            ,
            <given-names>J.B.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Gershman</surname>
            ,
            <given-names>S.J.:</given-names>
          </string-name>
          <article-title>Building machines that learn and think like people</article-title>
          .
          <source>Behavioral and Brain Sciences</source>
          <volume>40</volume>
          (
          <year>2017</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref12">
        <mixed-citation>
          12.
          <string-name>
            <surname>Metzinger</surname>
            ,
            <given-names>T.</given-names>
          </string-name>
          :
          <article-title>Two principles for robot ethics</article-title>
          .
          <source>Robotik und Gesetzgebung</source>
          pp.
          <volume>247</volume>
          {
          <issue>286</issue>
          (
          <year>2013</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref13">
        <mixed-citation>
          13.
          <string-name>
            <surname>Raoult</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Yampolskiy</surname>
          </string-name>
          , R.:
          <article-title>Reviewing tests for machine consciousness (</article-title>
          <year>2015</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref14">
        <mixed-citation>
          14.
          <string-name>
            <surname>Rosenthal</surname>
            ,
            <given-names>D.M.</given-names>
          </string-name>
          :
          <source>Varieties of higher-order theory 56</source>
          ,
          <volume>17</volume>
          {
          <fpage>44</fpage>
          (
          <year>2004</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref15">
        <mixed-citation>
          15.
          <string-name>
            <surname>Schneider</surname>
            ,
            <given-names>S.</given-names>
          </string-name>
          :
          <article-title>Superintelligent AI and the postbiological cosmos approach</article-title>
          . What is life (
          <year>2017</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref16">
        <mixed-citation>
          16.
          <string-name>
            <surname>Schwitzgebel</surname>
          </string-name>
          , E.:
          <article-title>Phenomenal consciousness, de ned and defended as innocently as i can manage</article-title>
          .
          <source>Journal of Consciousness Studies</source>
          <volume>23</volume>
          (
          <fpage>11</fpage>
          -
          <lpage>12</lpage>
          ),
          <volume>224</volume>
          {
          <fpage>235</fpage>
          (
          <year>2016</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref17">
        <mixed-citation>
          17.
          <string-name>
            <surname>Shanahan</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          :
          <article-title>Ascribing consciousness to arti cial intelligence</article-title>
          .
          <source>arXiv preprint arXiv:1504.05696</source>
          (
          <year>2015</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref18">
        <mixed-citation>
          18.
          <string-name>
            <surname>Silver</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          , et al.:
          <article-title>Mastering the game of go without human knowledge</article-title>
          .
          <source>Nature</source>
          <volume>550</volume>
          (
          <issue>7676</issue>
          ),
          <volume>354</volume>
          (
          <year>2017</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref19">
        <mixed-citation>
          19.
          <string-name>
            <surname>Singer</surname>
            ,
            <given-names>P.</given-names>
          </string-name>
          :
          <article-title>Practical ethics</article-title>
          . Cambridge university press (
          <year>2011</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref20">
        <mixed-citation>
          20.
          <string-name>
            <surname>Singler</surname>
            ,
            <given-names>B.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Smith</surname>
            ,
            <given-names>E.S.J.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Ramsay</surname>
            ,
            <given-names>C.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Uren</surname>
            ,
            <given-names>J.:</given-names>
          </string-name>
          <article-title>Pain in the machine: short lm</article-title>
        </mixed-citation>
      </ref>
      <ref id="ref21">
        <mixed-citation>
          21.
          <string-name>
            <surname>Sotala</surname>
            ,
            <given-names>K.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Gloor</surname>
            ,
            <given-names>L.</given-names>
          </string-name>
          :
          <article-title>Superintelligence as a cause or cure for risks of astronomical su ering</article-title>
          .
          <source>Informatica</source>
          <volume>41</volume>
          (
          <issue>4</issue>
          ) (
          <year>2017</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref22">
        <mixed-citation>
          22.
          <string-name>
            <surname>Tononi</surname>
            ,
            <given-names>G.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Boly</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Massimini</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Koch</surname>
            ,
            <given-names>C.</given-names>
          </string-name>
          :
          <article-title>Integrated information theory: from consciousness to its physical substrate</article-title>
          .
          <source>Nature Reviews Neuroscience</source>
          <volume>17</volume>
          ,
          <issue>450</issue>
          {
          <fpage>461</fpage>
          (
          <year>July 2016</year>
          )
        </mixed-citation>
      </ref>
    </ref-list>
  </back>
</article>