Our research result was featured on the Science with Sabine channel, run by famous YouTuber Sabine Hossenfelder, under the title ‘Scientists Measure Qualia for First Time - It was thought to be impossible.’ 

 As of June 6, it has received over 199,060 views and 3,300 comments, attracting a great deal of attention. Please take a moment to watch the video. The two original papers are available via open access, and we would be delighted if you could read them.

The two original papers featured are as follows:

1,

Paper Information

Authors:  Takahiro Hirao, Mitsuhiro Miyamae, Daisuke Matsuyoshi, Ryuto Inoue, Yuhei Takado, Takayuki Obata, Makoto Higuchi, Naotsugu Tsuchiya, and Makiko Yamada

Title: A Neuroimaging Dataset during Sequential Color Qualia Similarity Judgments with and Without Reports

Journal: Scientific Data 12, no. 1 (2025): 1-12. Accessed June 9, 2025

DOI: https://doi.org/10.1038/s41597-025-04511-0

Abstract

 Recent neuroscientific research has advanced our understanding of consciousness, yet the connection between specific qualitative aspects of consciousness, known as “qualia,” and particular brain regions or networks remains elusive. Traditional methods that rely on verbal descriptions from participants pose challenges in neuroimaging studies. To address this, our group has introduced a novel “qualia structure” paradigm that leverages exhaustive, structural, and relational comparisons among qualia instead of verbal reports. In this study, we present the fMRI dataset that captures relational similarity judgments among two out of nine color qualia per trial from 35 participants. This dataset also includes a “no-report” condition in half of the trials to assess the impact of overt reporting. Additionally, each participant’s color discriminability was evaluated with a hue test conducted outside the scanner. Our data offer valuable insights into the brain functions associated with color qualia and contribute to a deeper understanding of the neural foundations of consciousness.

2,

Paper Information

Authors:  Genji Kawakita, Ariel Zeleznikow-Johnston, Ken Takeda, Naotsugu Tsuchiya, Masafumi Oizumi

Title: Is my “red” your “red”?: Evaluating structural correspondences between color similarity judgments using unsupervised alignment

Journal: iScience Volume 28, Issue 3112029March 21, 2025

DOI: https://doi.org/10.1016/j.isci.2025.112029

Abstract

  Whether one person?s subjective experience of the ?redness? of red is equivalent to another?s is a fundamental question in consciousness studies. Intersubjective comparison of the relational structures of sensory experiences, termed ?qualia structures?, can constrain the question. We propose an unsupervised alignment method, based on optimal transport, to find the optimal mapping between the similarity structures of sensory experiences without presupposing correspondences (such as ?red-to-red?). After collecting subjective similarity judgments for 93 colors, we showed that the similarity structures derived from color-neurotypical participants can be ?correctly? aligned at the group level. In contrast, those of color-blind participants could not be aligned with color-neurotypical participants. Our results provide quantitative evidence for interindividual structural equivalence or difference of color qualia, implying that color-neurotypical people?s ?red? is relationally equivalent to other color-neurotypical?s ?red?, but not to color-blind people?s ?red?. This method is applicable across modalities, enabling general structural exploration of subjective experiences.

AB  - Whether one person?s subjective experience of the ?redness? of red is equivalent to another?s is a fundamental question in consciousness studies. Intersubjective comparison of the relational structures of sensory experiences, termed ?qualia structures?, can constrain the question. We propose an unsupervised alignment method, based on optimal transport, to find the optimal mapping between the similarity structures of sensory experiences without presupposing correspondences (such as ?red-to-red?). After collecting subjective similarity judgments for 93 colors, we showed that the similarity structures derived from color-neurotypical participants can be ?correctly? aligned at the group level. In contrast, those of color-blind participants could not be aligned with color-neurotypical participants. Our results provide quantitative evidence for interindividual structural equivalence or difference of color qualia, implying that color-neurotypical people?s ?red? is relationally equivalent to other color-neurotypical?s ?red?, but not to color-blind people?s ?red?. This method is applicable across modalities, enabling general structural exploration of subjective experiences.