Human consciousness and cognition go hand in hand, but require different types of explanations

Summary

Consciousness is not an epiphenomenon but a prerequisite for most purposeful behaviors in humans. Over the past two decades, consciousness science has advanced from descriptive correlations to mechanistic predictions, with the Perturbational Complexity Index (PCI) from TMS-EEG indicating about a 95% probability of detecting consciousness in non-communicative patients when purposeful behavior is present. Recent studies in neurotypical individuals and communicative patients, using refined statistical methods and awareness scales validated by subjective reports, consistently suggest that some degree of stimulus awareness is necessary for above-chance performance. Consciousness, intelligence, and cognitive abilities can dissociate, motivating Integrated Information Theory, which generates testable predictions about conscious states independently of behavior.

Study at a glance

Abstract

Over the past two decades, consciousness science has advanced from descriptive correlations to mechanistic predictions. Core requirements for conscious states have been clarified, and new diagnostic tools — most notably the Perturbational Complexity Index (PCI) derived from TMS–EEG — are moving toward clinical use. PCI indicates about a 95% probability of detecting consciousness in non-communicative patients when purposeful behavior is present. Recent studies in neurotypical individuals and communicative patients have adopted refined statistical methods accounting for regression-to-the-mean effects, along with rigorous awareness scales directly validated by subjective reports. Contrary to mainstream beliefs, these approaches consistently suggest that some degree of stimulus awareness is necessary for above-chance performance. Consciousness thus emerges not as an epiphenomenon but as a prerequisite for most purposeful behaviors in humans. This methodological progress opens new opportunities to bridge the long-standing divide between consciousness and cognitive sciences. At the same time, consciousness, intelligence and cognitive abilities are not identical: they can dissociate in revealing ways. Subjective experience exceeds its behavioral expression and remains accessible only to the experiencer. These observations motivate Integrated Information Theory, an explanatory framework that generate testable predictions about conscious states and qualitative contents independently of behavior, while also predicting that energy efficiency requirements may give rise to a tight link between consciousness and cognition in biological systems. Clinical and neuroscientific implications of such framework are discussed.