The relationship between conscious experience and brain activity has intrigued scientists and philosophers for centuries. In the last decades, several theories have been proposed to answer this long-lasting set of questions. These theories have developed in parallel, with little to no crosstalk among them.

We rapidly advance research on consciousness, through an adversarial collaboration between proponents of two leading theories in the field, Global Neuronal Workspace (GNW) and Integrated Information Theory (IIT). Very briefly, GNW claims that conscious processing emerges when information is globally broadcasted by a frontoparietal network. A non-linear ‘ignition’ response involves the amplification of information and its sharing across brain areas. IIT, conversely, equates consciousness with a maximum of irreducible intrinsic cause–effect power, as determined from the intrinsic perspective of the system. It further claims that a local maximum of such power likely resides in the posterior ‘hot zone’.

We built two studies that test contradictory predictions of these theories, each being implemented via a dedicated experimental setup. Predicted outcomes should either support, refute, or challenge these theories, which ultimately will lead to a breakthrough in several fields of research.

In six theory-impartial laboratories we are currently conducting both studies using three complementary methods: fMRI, MEG/EEG, and ECoG. We include built-in replications, both between labs and within datasets.

The general goals of Experiment 1 are to measure brain activity elicited by stimuli that are undoubtedly consciously perceived while manipulating (1) the task, such that some stimuli are relevant while others are irrelevant and (2) stimulus duration, such that some stimuli are perceived briefly while others are perceived for extended periods of time. This experimental framework independently tests critical predictions of GNW and IIT, concerning information about a clearly visible stimulus whose decodability should not depend on whether the percept is task-relevant or not, and that the physical substrate of consciousness should remain active throughout the presentation of a clearly visible stimulus (whether task-relevant or not).

The general goal of Experiment 2 is to measure brain activity elicited by salient visual stimuli that are reported as seen versus unseen in the context of a secondary task due to competing attentional demands – a critical test of GNW predictions and key to conscious perception, regardless of the task. The framework also tests IIT’s central prediction that activity and patterns of connectivity within posterior cortical areas will be consistent across all task conditions for seen stimuli, triggering similar experiences, but different for seen stimuli triggering different experiences.

Through this ambitious and large-scale undertaking, involving 11 laboratories on three continents, and using an adversarial collaborative process, we will provide decisive evidence in favor or against the two theories and clarify the footprints of conscious visual perception in the human brain, while also providing an innovative model of large-scale, collaborative, and open science in the field of consciousness research.