Morales, Jorge

Phillips, Ian B.

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Trends in Cognitive SciencesTICS 1988 No. of Pages 2Box 1. Completely Unconscious Rivalry TransitionsIt is possible (albeit unlikely in our view) that rivalrous changes are genuinely invisible in the same color condi-tion, not merely indiscriminable from objective changes. However, this does not avoid our concerns. If rivalrouschanges are invisible, we will not predict any contrast in frontal activity due to differences in consciouslyperceived change: there are no such differences. However, since rivalry still occurs, one interval could containat most one extra change in perceptual contents. Yet, since there are multiple matching objective contentchanges in both intervals, we again will not predict a measurable difference in BOLD activity. Even moresensitive analyses of the data (e.g., multivoxel pattern analysis) or more sensitive methods (e.g., electrocorti-cography), which Brascamp et al. did not use [11], may well still fail to detect such subtle differences.LetterThe FundamentalProblem withNo-CognitionParadigmsIan Phillips ,1,* andJorge Morales2A central controversy in consciousnessscience concerns whether the neuralcorrelates of consciousness (NCCs) exclu-sively reside posterior to the central sulcusor also include frontal regions [1–4]. In arecent Trends in Cognitive Sciencesarticle, Block [5] contends that popular‘no-report’ paradigms [6,7] cannot settlethis dispute, since absence of report isconsistent with extensive private cogni-tion. To make progress, we instead re-quire a ‘no-cognition’ (or more precisely,‘no-post‐perceptual cognition’) paradigm.According to Block, doubts about suchapproaches [8–10] are misplaced, sinceBrascamp et al. [11] have already devel-oped precisely such a paradigm. Block isrightly dissatisﬁed with no-report methods.However, a fundamental difﬁculty faces no-cognition paradigms, as examination ofBrascamp et al.’s study reveals.Brascamp et al. exploit binocular rivalry: thepresentation of different stimuli to each eye,leading to alternating percepts. Speciﬁcally,they presented each eye with a distinct pat-tern of quasi-randomly moving dots with40% motion coherence. These dotschanged direction every 300 ms, creatingan impression of high-tempo jitter in theirglobal motion. Average dot motion was or-thogonal across patterns, creating twotypes of transition: objective transitions,where the dots physically changed directionevery 300 ms, and rivalry transitions, wherea switch in eye dominance changed the per-ceived motion direction every few seconds.When dots differed in color across eyes,rivalrous transitions were easily detectable.However, when dots were the same color,although rivalry transitions still occurred,observers detected them eight times lessfrequently, a level insigniﬁcantly differentfrom chance. This is plausibly becausesuch changes, while visible, could notbe distinguished from objective changes indot dynamics (i.e., the constant jitter in globalmotion). (In Box 1, we discuss the possibilitythat such transitions were in fact invisible.)According to Block, what is theoreticallyimportant is that ‘this method avoids thesystematic change of cognitive states…that can accompany rivalrous changes’.Thus, the methodology is ‘not just a no-report methodology: it is a no-differential-post-perceptual cognition methodology’.Yet, Brascamp et al.’s paradigm doesnot avoid systematic changes of cognitivestates. All it avoids are thoughts spe-ciﬁcally tied to rivalrous transitions asopposed to objective changes in dotdynamics. Nothing in Brascamp et al.’smethodology prevents observers engag-ing in extensive cognitive processingwhen transitions occur, so long as similarprocessing attends objective changes. In-deed, Brascamp et al. precisely designedtheir displays so that the appearance ofobjective change closely matched that ofrivalry-driven change, so we should ex-pect close similarities. Cognitive process-ing cannot be expected to distinguish thesubjectively indistinguishable.This fundamentally compromises Block’sinterpretation of Brascamp et al.’s fMRIdata. Brascamp et al. calculated blood-oxygen level-dependent (BOLD) contrastsTrbetween intervals inferred to contain arivalry transition and intervals inferredto be transition free in three overlappingfrontoparietal and temporoparietal atten-tional networks. No evidence was foundthat this activation differed from modelpredictions, which treated BOLD activa-tion as a function of transition reportability.Thus, a large contrast was found in thedifferent color condition and a muchsmaller contrast in the same color condi-tion. However, this does not indicate anabsence of activity in target regions ac-companying transitions. It only showsthat this activity does not signiﬁcantly differbetween intervals with and withouttransitions. Moreover, since both intervalscontain multiple objective changesengineered to look just like rivalrous transi-tions, it is unsurprising if subjects respondto both intervals in very similar ways. Com-pared with the different color condition,where there is a dramatic difference inthe type of change between intervals,there is effectively no detectable differencein the same color condition.What is evidenced by the absence of con-trast is that frontal areas do not causallyinitiate transitions. This was the purpose ofBrascamp et al.’s study. However, weshould not conﬂate the property of causingtransitions with the property of being anNCC of rivalrous changes or contents. Sen-sory circuits may determine when changesbetween contents occur, even though pre-frontal circuits are constitutively involved inour awareness of them. This hypothesisis consistent with the ﬁnding that invisiblestimuli elicit switches detectable in sensorycortex but not in frontal regions [12].ends in Cognitive Sciences, Month 2019, Vol. xx, No. xx 1Trends in Cognitive SciencesThis methodological point generalizesto all studies that subtract activity duringrivalry from activity during a ‘replay’condition, designed to mimic observers’percepts during rivalry using a singleexternal stimulus (e.g., [6]). Such subtrac-tion methods help determine the etiologyof transitions. However, they are not suit-able for establishing NCCs [10]. AlthoughBlock partially acknowledges this pointabout ‘replay’ subtraction, he does notappreciate that the issue representsan in-principle problem for rivalry-based‘no-cognition’ paradigms. As Block re-marks, we cannot stop subjects thinking.At most, we can match their thinkingacross conditions (or intervals). However,to match thinking requires conditions thatare indiscriminable in some relevant re-spect. Yet, indiscriminable stimuli lookthe same. Consequently, all sides willpredict matching frontal activity between2 Trends in Cognitive Sciences, Month 2019, Vol. xx, No. xxconditions with and without transitions.Thus, such paradigms cannot discrimi-nate rival hypotheses concerning NCCs.AcknowledgmentsThanks to Ned Block and Jan Brascamp for helpfuldiscussion.1Department of Philosophy and Department of Psychologicaland Brain Sciences, Johns Hopkins University, Baltimore, MD21218, USA2Department of Psychological and Brain Sciences, JohnsHopkins University, Baltimore, MD 21218, USA*Correspondence:ianbphillips@jhu.edu (I. Phillips).https://doi.org/10.1016/j.tics.2019.11.010© 2019 Elsevier Ltd. All rights reserved.References1. Dehaene, S. and Naccache, L. (2001) Towards a cognitiveneuroscience of consciousness: basic evidence and aworkspace framework. Cognition 79, 1–372. Lau, H. and Rosenthal, D. (2011) Empirical support forhigher-order theories of conscious awareness. TrendsCogn. Sci. 15, 365–3733. Lamme, V.A.F. (2010) How neuroscience will change ourview on consciousness. Cogn. Neurosci. 1, 204–2204. Boly, M. et al. (2017) Are the neural correlates ofconsciousness in the front or in the back of the cerebralcortex? Clinical and neuroimaging evidence. J. Neurosci.37, 9603–96135. Block, N. (2019) What is wrong with the no-report para-digm and how to ﬁx it. Trends Cogn. Sci. 23, 1003–10136. Frässle, S. et al. (2014) Binocular rivalry: frontal activityrelates to introspection and action but not to perception.J. Neurosci. 34, 1738–17477. Tsuchiya, N. et al. (2015) No-report paradigms: extractingthe true neural correlates of consciousness. Trends Cogn.Sci. 19, 757–7708. Overgaard, M. and Fazekas, P. (2016) Can no-reportparadigms extract true correlates of consciousness?Trends Cogn. Sci. 20, 241–2429. Odegaard, B. et al. (2017) Should a few null ﬁndings falsifyprefrontal theories of conscious perception? J. Neurosci.37, 9593–960210. Phillips, I. (2018) The methodological puzzle of phenome-nal consciousness. Philos. Trans. R. Soc. B 373, 1–911. Brascamp, J. et al. (2015) Negligible fronto-parietal BOLDactivity accompanying unreportable switches in bistableperception. Nat. Neurosci. 18, 1672–167812. Zou, J. et al. (2016) Binocular rivalry from invisible patterns.Proc. Natl. Acad. Sci. U. S. A. 113, 8408–8413

The Fundamental Problem with No-Cognition Paradigms

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The Fundamental Problem with No-Cognition Paradigms

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