Detecting Consciousness Through Neuroimaging: Understanding the Risks

Modern neuroimaging techniques, such as fMRI and EEGs, allow us to get a glimpse into the mind of individuals in a vegetative or behaviourally unresponsive clinical state. In particular, recent research indicates that we can use these techniques to determine if an unresponsive individual is truly conscious.

The success of these techniques, at least in a controlled setting, mean that it is more likely such evidence will be submitted in trials: whether to assist in end-of-life decisions or in factual determinations such as determining harm in a criminal or civil proceedings.

A recent paper in the journal Neuroimage: Clinical looks at the risks posed by diagnostic error in using neuroimaging to detect consciousness. In particular, it looks at the likelihood and potential repercussions of a false-positive or false negative result.


In recent years, a number of new neuroimaging techniques have detected covert awareness in some patients previously thought to be in a vegetative state/unresponsive wakefulness syndrome. This raises worries for patients, families, and physicians, as it indicates that the existing diagnostic error rate in this patient group is higher than assumed. Recent research on a subset of these techniques, called active paradigms, suggests that false positive and false negative findings may result from applying different statistical methods to patient data. Due to the nature of this research, these errors may be unavoidable, and may draw into question the use of active paradigms in the clinical setting. We argue that false positive and false negative findings carry particular moral risks, which may bear on investigators’ decisions to use certain methods when independent means for estimating their clinical utility are absent. We review and critically analyze this methodological problem as it relates to both fMRI and EEG active paradigms. We conclude by drawing attention to three common clinical scenarios where the risk of diagnostic error may be most pronounced in this patient group.


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