Consciousness Unraveled: Descartes, Integrated Information Theory, and the Brain

In this Science Quickly episode, host Kendra Pierre Lewis interviews Alison Parshall about the mystery of consciousness. They discuss why there is no single definition of consciousness, describe wakefulness, internal awareness, and connectedness as core dimensions, and explain how the Integrated Information Theory frames consciousness as unitary and information-rich. The conversation compares dreaming, anesthesia, and waking life to tease apart which brain states count as conscious experience. They also tackle whether machines or non-human animals could be conscious and consider the philosophical challenge of bridging subjective experience with brain activity. 

Overview and framing

In this episode of Scientific American Science Quickly, Kendra Pierre Lewis speaks with Alison Parshall about the enduring mystery of consciousness. The discussion begins by acknowledging the lack of a single, universally accepted definition of consciousness and then lays out a practical framework for thinking about it in everyday terms: wakefulness, internal awareness, and connectedness. This triad anchors the conversation as they navigate why consciousness is considered one of the most challenging questions in neuroscience and philosophy of mind. "There are three dimensions that I think of when we think about consciousness. One of them is wakefulness." - Alison Parshall

Defining consciousness and the language problem

The piece emphasizes how the word consciousness is messy, spanning everything from being awake to the qualitative experience of being aware. Parshall explains that the field grapples with the mind-brain relationship, including enduring philosophical tensions between dualism and materialism. They discuss the practical stance that science tends to adopt, acknowledging the difficulty of connecting first-person experience with physical brain processes. "The English word consciousness is a little bit of a mess, so we have to kind of forgive it for that." - Alison Parshall

The Integrated Information Theory (IIT) perspective

A central portion of the interview centers on IIT, a theory that foregrounds subjective experience by grounding it in information integration. Parshall describes IIT as focusing on two core ideas: unity, meaning a single stream of consciousness, and high information content within that integrated system. The discussion notes how brain networks communicate and how loss of integration correlates with loss of consciousness across states such as sleep or anesthesia. "consciousness is unitary" - Alison Parshall

Dreaming, anesthesia, and altered states

The conversation moves to altered states of consciousness, such as dreaming and anesthesia, to illustrate what remains when wakefulness or environmental connectedness shifts. Parshall outlines a multi-dimensional view of consciousness and explains how dreaming preserves internal awareness while losing wakefulness and connectedness. The hosts discuss the ethical and scientific considerations of experimenting with consciousness during anesthesia. "In dreaming, you don't have wakefulness and you don't have connectedness, but you do have internal awareness." - Alison Parshall

Consciousness, AI, and non-human animals

The episode also considers the implications for AI and animal consciousness. Parshall notes that most AI researchers regard current language models as far from conscious, while the brain-centered perspective raises questions about what ground truth can be transferred to machines. The discussion touches on animal consciousness, highlighting consensus that all mammals are conscious, while also recognizing the philosophical and empirical complexities of attributing consciousness to fish or insects. "there's fairly wide consensus that all mammals are conscious" - Alison Parshall