The Dream Catcher experiment: blinded analyses failed to detect markers of dreaming consciousness in EEG spectral power.

Levente Móró,Antti Revonsuo,Jennifer Windt,Naotsugu Tsuchiya,William Wong,Valdas Noreika,Katja Valli

doi:10.1093/nc/niaa006

Abstract

The Dream Catcher test defines the criteria for a genuine discovery of the neural constituents of phenomenal consciousness. Passing the test implies that some patterns of purely brain-based data directly correspond to the subjective features of phenomenal experience, which would help to bridge the explanatory gap between consciousness and brain. Here, we conducted the Dream Catcher test for the first time in a step-wise and simplified form, capturing its core idea. The Dream Catcher experiment involved a Data Team, which measured participants’ brain activity during sleep and collected dream reports, and a blinded Analysis Team, which was challenged to predict, based solely on brain measurements, whether or not a participant had a dream experience. Using a serial-awakening paradigm, the Data Team prepared 54 1-min polysomnograms of non-rapid eye movement sleep—27 of dreamful sleep and 27 of dreamless sleep (three of each condition from each of the nine participants)—redacting from them all associated participant and dream information. The Analysis Team attempted to classify each recording as either dreamless or dreamful using an unsupervised machine learning classifier, based on hypothesis-driven, extracted features of electroencephalography (EEG) spectral power and electrode location. The procedure was repeated over five iterations with a gradual removal of blindness. At no level of blindness did the Analysis Team perform significantly better than chance, suggesting that EEG spectral power could not be utilized to detect signatures specific to phenomenal consciousness in these data. This study marks the first step towards realizing the Dream Catcher test in practice.

Highlights

BackgroundIf we take consciousness to be a natural, biological phenomenon that depends on the neural activity of the brain, there must be objective patterns of brain activity that directly constitute consciousness and correspond to the subjective features of experience
Major differences were manifest in the EOG and EMG features, the Analysis Team had no rationale based on the literature for using them to determine which cluster corresponded to dreamfulness
The Data Team determined the accuracy of this classification to be 59%, which was not significantly different from chance

Summary

Introduction

If we take consciousness to be a natural, biological phenomenon that depends on the neural activity of the brain, there must be objective patterns of brain activity that directly constitute consciousness and correspond to the subjective features of experience. The Dream Catcher test was introduced as an empirical criterion for what would constitute a genuine scientific discovery of the underlying neural constituents of phenomenal consciousness (Revonsuo 2006). The present empirical study, which we call the Dream Catcher experiment, is the first attempt to execute a simplified version of such a test. Revonsuo (2006) proposed that consciousness would be genuinely explained by the discovery of constitutive mechanisms of consciousness at the phenomenal level. Even if one were able to identify the neural correlates of consciousness, those would not suffice to bridge the explanatory gap: correlations do not in themselves provide an explanation for a phenomenon. Revonsuo (2006) proposed that consciousness would be genuinely explained by the discovery of constitutive mechanisms of consciousness at the phenomenal level. [For the crucial distinction between correlates and constituents, see Revonsuo (2001) and Miller (2015).]

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