Does Cognitive Load Affect Measures of Consciousness?

Candidate neural measures of consciousness must be specific to conscious level rather than to other factors that modulate brain activity, such as attention, task demands, or arousal. This specificity—often called the “conjunction problem” or the “task-relatedness confound”—has been rarely subjected to direct empirical test.

The study recorded 64-channel EEG from 12 participants in two within-session conditions: passive attendance to auditory and visual stimuli (low cognitive demand), and performance of an n-back working memory task (high cognitive demand). Several EEG-based consciousness measures were computed from both conditions, including signal complexity, spectral, and connectivity-based metrics.

The core finding is that several proposed measures did not differ significantly between conditions, despite EEG data confirming that participants showed the expected physiological responses to increased task load. This constitutes evidence that at least some consciousness measures are not trivially inflated by general cognitive engagement, bolstering their candidacy as indices of conscious level rather than of mental effort or task-relevance processing. The paper discusses which measures showed the greatest robustness and what residual concerns remain for their use in clinical and experimental contexts.

Recommended citation: Sevenius Nilsen A, Storm JF, Juel BE. (2024). "Does Cognitive Load Affect Measures of Consciousness?" Brain Sciences. 14(9):919. https://doi.org/10.3390/brainsci14090919
Download Paper