Garima or simply expressing thoughts using language. The


Steve Chang

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Cognitive Neuroscience

Dec 7, 2017

Evaluating the Effectiveness of
No-Report Paradigms in Consciousness Research

I. Introduction

            The problem of consciousness is
often considered the biggest question in modern neuroscience. Where
consciousness stems from in the brain and how researchers can recognize it when
looking at brain activity are two big questions that remain to be solved. However,
researching consciousness comes with many issues that researchers need to
decide between in order to conduct the most effective and accurate studies.
Indeed, one problem is simply the definition of consciousness itself. The term
often seems to be conflated with directing attention or visual perception or
simply expressing thoughts using language. The conflict over the very
definition of the phenomenon itself poses a challenges to researchers trying to
study it. Another contentious issue is just the different types of methods used
to study consciousness. This paper will consider one type of approach to
studying consciousness, the no-report paradigm.

The Issue

            Most traditional research into
consciousness uses a report-based paradigm i.e. subject’s reports of perceiving a stimulus as
evidence of consciousness. However, trying to extract information about the
neural correlates of consciousness from such information can be difficult and
has many confounds. The primary issue with this method is that the neural
circuitry used to report an experience will be interpreted as a part of the
neural correlate of consciousness (NCC) (Tsuchiya et al, “No-Report”). This
results in an overestimation of the NCC (Tsuchiya et al, “No-Report”). Additionally, many other
mechanisms work together to allow a subject to report a change in their
perception, including attention, working memory, or expectation (Tsuchiya et
al, “No-Report”). Therefore, some
researchers try to find a way to study consciousness without asking a subject
to report when they are consciously aware of the stimulus. This method of
studying consciousness is called a no-report paradigm. A stumbling block in
using no-report paradigms is how to actually find evidence of conscious
perception without a subject reporting their experience to the researchers.
Tuschiya et al demonstrate that it is possible to use eye movement, pupil size,
memory-based reports, or nonverbal reporting measures as a substitute for
reporting perception of a stimulus. So, such measures will be used to time the
neural response to see when the activity in the brain corresponds to conscious

            There is scientific evidence that
no-report paradigms probably help in eliminating the overestimation of the NCC.
Binocular rivalry task is the most common type of task used to study
consciousness. When two conflicting stimuli are presented to the two eyes
simultaneously, perception switches every few seconds. Although both images are
seen, only one is consciously perceived at any particular moment in time. A
binocular rivalry task is typically done under a report paradigm where subjects
report every time their perception changes. Compared to a control condition
where no conflicting stimuli are shown, one can find the difference in brain activity
between the two conditions which is likely associated with the switches of
perception. Tushiya et al mention two experiments that show that in binocular
rivalry tasks, using a no-report paradigm results in different areas of the
brain being activated as part of conscious perception. Typically, frontoparietal activation
is seen in report paradigms with binocular rivalry tasks. However, in the
studies under no-report paradigms, frontoparietal activation is not different
between both conditions. Therefore, it is possible that the frontoparietal
activation observed is actually an overestimation of the NCC. Additionally, TMS
and lesions to the frontal lobes did not affect conscious perception.

Benefits and Drawbacks of Using No-Report Paradigms

            There are definite benefits to using
no-report paradigms. As mentioned, no-report paradigms are likely to eliminate the risk of
overestimating the NCC by not including post-NCC processing in the measurements
of brain activity. Another major benefit of using a no-report paradigm is that one can conduct
studies on subjects that cannot report what they are perceiving in verbal
language (Tsuchiya et al, “No-Report”). This extends to
animals and opens up wider possibilities of studies to be done. It allows for
further lesion studies to be done, as carefully controlled lesions are
difficult to find in humans but can be created in certain animals. Furthermore,
studies of consciousness can be done in humans who cannot report their
experiences using language. This opens up the potential of doing studies in
babies, which could help clarify when consciousness develops in humans.

            However, there is also
significant evidence that no-report paradigms are not an appropriate methods to
use in consciousness studies. First, the confounds of no-report paradigms can
be equal to report paradigms and still run the risk of overestimating the NCC
(Overgaard and Fazekas). Instead of overestimating the NCC by including
post-NCC processing to report a change, no-report paradigms could easily
mistake unconscious processing for part of the NCC. Overgaard and Fazekas also
argue that the no-report paradigm is not immune to including post-NCC processing.
Simply because a subject is not verbally reporting their perceptions does not
mean that they do not engage in introspection and higher-order processing that
is not part of the NCC (Overgaard and Fazekas). It seems that the only way to
design an experiment that does not involve reporting is to rely on the
researcher’s intuition that a conscious experience will be occurring for the
subject during a certain task. Furthermore, Overgaard and Fazekas critique Tsuchiya
et al’s main source of evidence for the no-report paradigm, which is the lack
of difference in frontoparietal activation between binocular rivalry and a
control condition in a no-report paradigm.  A later paper found that this difference in
results is actually not present because the activation was still seen when
monkeys viewed binocular rivalry conditions passively (Odegaard). Examining evidence from various studies of the PFC in relation to
consciousness, the paper concludes that this activity is related to creating
consciousness. So, no-report paradigms do not actually show an important
difference in activity when compared to report paradigms, as the frontal cortex
appears to be important in conscious perception regardless of the paradigm


            Evaluating arguments on both sides
of the debate, it may be more useful to combine report and no-report paradigms
to study consciousness. Along with the arguments mentioned by Overgaard and
Fazekas that critique no-report paradigms, it is also possible that the choice
of evidence of perceptual changes could be flawed. Overgaard and Fazekas
mention that pupil dilation and eve movement can represent pre conscious
events. They could also represent an entirely different process, such as the
shifting of visual attention which is not necessarily the equivalent of
conscious perception.

            Furthermore, if an integration model
of consciousness is correct, then it may be counterproductive to study
consciousness by isolating pre-NCC processing from the NCC and from post-NCC
processing. Perhaps all these processing events together create consciousness.
A combination of attention shifting, movement, and putting a perceived event
into language could be what creates a conscious event, so there is no way to
separate consciousness from these events. However, Tischuya et al’s response to
this argument is compelling. The NCC is still separate from the phenomena that
integrate information as there has to be a way that information became
conscious after being integration. Here, the primary question of the definition
of consciousness is raised again. At what point can a stimulus be conscious?
Does the integration of information create awareness of the stimulus at a level
which can be called conscious? Or does the
a later paper in response to Overgaard and Fazekas, Tushiya clarify the
necessity to use both report and no-report paradigms to study consciousness (Tsuchiya et al, “Response”). This does
seem like a way solve several of the issues this paper has discussed. The
primary problem of overestimated the NCC can be solved for by looking at the
activation that is common between no-report and report paradigms, assuming that
both will overestimate the NCC in opposite ways, including other higher-order
processing or including unconscious processing. This seems like the logical way
to use no-report paradigms given the complications with using them exclusively
as a paradigm under which to study consciousness.

V. Conclusion

            Report paradigms
present the challenge of possibly overestimating the NCC by including post-NCC
processing. An easy solution to this question seems to be to eliminate
reporting altogether using a no-report paradigm. However, this comes with its
own issues of overestimating the NCC by including pre-NCC processing and
possibly approaching the problem of consciousness from the wrong angle.
Therefore, it seems like it is not appropriate to use solely a no-report
paradigm, but rather to use both a report paradigm and a no-report paradigm to
study the neural correlates of consciousness.


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