An interventional study of Inner Experience Induction Tasks and hdEEG in Healthy Volunteer, Inner Speech and Visual Mental Imagery, sponsored by University of Liege. Recruiting at 1 site in Belgium. Open to participants aged 18 Years to 70 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-10-21.
Sponsored by University of Liege · Not applicable, Interventional, and Basic science
The purpose of this study is to investigate the brain activity associated with two common inner experiences: visual mental imagery (mentally seeing objects or actions) and inner speech (experiencing language without speaking out loud). Researchers aim to identify the most effective tasks to generate robust and detectable brain signals (EEG biomarkers) for these experiences in healthy adults. Participants will complete questionnaires and perform specific mental tasks, such as silently repeating words or imagining movements and faces, while their brain activity is recorded using high-density electroencephalography (hdEEG). These tasks will be compared to resting and passive listening conditions to better understand the relationship between inner experiences, self-awareness, and neurophysiology.
Background and scientific rationale :
The most frequently reported subjective experiences in the general population are visual mental imagery (VMI) and inner speech (IS). VMI refers to the ability to mentally "see" objects or actions in their physical absence, while IS is defined as the subjective experience of language without overt articulation. IS presents several phenomenological aspects, such as condensation, evaluative aspects, dialogic properties, and the involvement of others. It has been associated with high-level consciousness, self-reflection, and metacognition. Previous studies have identified EEG biomarkers reflecting the induction of both IS (e.g., N400, theta, beta, and gamma bands) and VMI (e.g., alpha band desynchronization, anterior negativity). The primary objective of this study is to determine which neurophysiological biomarkers resulting from the induction of these inner experience tasks are the most robust.
Study hypotheses :
The research is driven by three main hypotheses:
General experimental plan :
The study will enroll neurotypical conscious adult participants. The experimental session involves both behavioral and neurophysiological assessments. First, participants will complete validated questionnaires evaluating self-consciousness and inner experiences, including the Short French Meta-Cognitions Questionnaire (MCQ-30), the Rumination-Reflection Questionnaire (RRQ), the Varieties of Inner Speech Questionnaire-Revised (VISQ-R), and the Vividness of Visual Imagery Questionnaire (VVIQ).
Following a training phase, participants will undergo high-density electroencephalography (hdEEG) recording during resting state and experimental tasks. The paradigms consist of four mental imagery conditions:
After each main task block, participants will retrospectively evaluate their subjective experiences using visual analog scales (VAS) to assess task success, modality used, generated content, perceived difficulty, and modality mixing.
Data analyses will investigate behavioral measures and neurophysiological signatures (such as beta and gamma bands for IS, and alpha band for VMI) using standard statistical approaches. In an exploratory approach, a deep learning model based on a Convolutional Neural Network (CNN) will also be tested to classify EEG signals reflecting IS or VMI.
Clinical perspectives :
The investigation of these inner experiences and their biomarkers opens long-term clinical applications. For patients with aphasia, these tools could help determine if IS is preserved despite the loss of overt speech, and explore its potential impact on anosognosia. Additionally, for patients with disorders of consciousness, these neurophysiological tools could offer the opportunity to investigate "hidden cognition", ultimately contributing to reducing clinical diagnostic errors.
University of Liege is the lead sponsor of 250 studies on the registry; 49 are open to participants now.
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Exclusion Criteria:
Participants undergo a single experimental session. They first complete behavioral questionnaires evaluating self-consciousness and inner experiences (MCQ-30, RRQ, VISQ-R, VVIQ). Following a training phase, their brain activity is recorded using high-density electroencephalography (hdEEG). During the EEG recording, they perform cognitive tasks designed to induce inner speech (auditory and visual presentation of words) and visual mental imagery (imagining hand movements and familiar faces). Resting state and passive listening conditions are also recorded as baselines. Finally, they evaluate their subjective experience using visual analog scales.
Behavioral: Inner Experience Induction Tasks and hdEEG
The intervention consists of performing specific mental tasks to induce inner speech (mentally repeating heard or read words) and visual mental imagery (mentally visualizing a hand movement or a loved one's face). These tasks are performed while high-density EEG (hdEEG) is recorded. The protocol also includes a resting state period, a passive listening control condition, and the completion of psychological questionnaires (MCQ-30, RRQ, VISQ-R, VVIQ).
Modulation of EEG spectral power (Alpha, Beta, and Gamma bands)
The primary evaluation relies on the analysis of high-density EEG signals in response to the induction of inner experiences. Specifically, the analysis will focus on identifying the most robust paradigms by examining specific EEG characteristics: modulation in the beta and gamma frequency bands for Inner Speech (IS), and alpha band desynchronization for Visual Mental Imagery (VMI). The goal is to identify the most appropriate and effective tasks to generate these detectable biomarkers.
Time frame: Day 1
Difference in EEG biomarkers between passive listening and active mental repetition
Investigating the neurophysiological correlates of the passive listening of words in comparison with their silent repetition (Inner Speech). This involves a comparative analysis of EEG biomarkers between these different tasks to determine the specific electrophysiological signatures of active mental generation versus passive semantic processing.
Time frame: Day 1
Correlation between self-consciousness scores and phenomenological dimensions of inner speech
To better understand the links between self-consciousness and the phenomenological components of inner speech. Self-consciousness will be evaluated using the Short French Meta-Cognitions Questionnaire (MCQ-30) and the Rumination-Reflection Questionnaire (RRQ). These scores will be correlated with the detailed profile of inner experiences obtained through the Varieties of Inner Speech Questionnaire-Revised (VISQ-R) and the Vividness of Visual Imagery Questionnaire (VVIQ). A specific aim is to evaluate whether increased reflective consciousness is positively correlated with the dialogic and evaluative/critical dimensions of inner speech.
Time frame: Day 1
Plan to share: Undecided — In accordance with the study protocol and the informed consent form approved by the local Ethics Committee, access to the data is strictly restricted to the authorized researchers of the GIGA-Consciousness research unit directly involved in this study. To ensure strict participant confidentiality and full compliance with the European General Data Protection Regulation (GDPR), individual participant data (IPD) might not be shared with external researchers or third parties.
Start is estimated for Oct 2026; primary completion for Oct 2027, 12 months later.
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From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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