This opinion article argues that the contrastive analysis approach, which compares neural activity during conscious versus unconscious perception, has been the most productive method in consciousness research. It contends that this method is not merely a tool but has shaped the very questions researchers ask about consciousness. The author suggests that focusing on the contents of consciousness, particularly through criterion contents of report, provides a more tractable path forward than seeking a single neural correlate of consciousness. The article concludes that the contrastive approach will continue to yield progress by refining our understanding of the neural differences underlying conscious experience.
Consciousness arises from the interaction of two distinct brain mechanisms: one that represents the specific contents of perception and cognition (the data) and another that regulates the level of activity of those contents. Neither mechanism alone is sufficient; without specific contents there is no conscious experience, and without sufficient activity those contents remain unconscious. When both are activated to the necessary degree, they jointly provide conditions sufficient for conscious experience to emerge. This theoretical integration combines two previously separate research traditions—one studying the contents of conscious experience and the other studying the level of consciousness—and emphasizes understanding the mechanisms of consciousness rather than mere correlates.