Connecting clinical and experimental investigations of awareness in traumatic brain injury.

Questionnaire-based demonstrations of impaired self-awareness (SA) after traumatic brain injury (TBI) are not always supported by experimental studies of in-the-moment or online awareness. This chapter begins by describing the clinical phenomenon of impaired SA, how it is measured, and why its interdependency with mechanisms of online awareness may provide the scaffolding from which appraisals of cognitive functioning can be accurately revised following a brain injury. We review research that has measured unawareness of errors in routine action in TBI patients and propose more rigorous methodological approaches to studying the emergent properties of awareness with greater clarity in the laboratory. We discuss how neuropsychological and electrophysiologic studies are beginning to inform our understanding of impaired error processing in TBI patients and we highlight recent theory proposing that online metacognitive processes accumulate evidence of erroneous responses in a graded fashion. Neural signals with amplitudes that scale with the strength of accruing evidence and peak latencies that mark the threshold at which awareness emerges represent important neural mechanisms to examine the breakdown of error awareness after brain injury. We also discuss how errors can be investigated in relation to different sources of evidence that contribute to aware experiences after brain injury. Finally, we explore conditions beyond error signaling, and how different "objects of insight" that require retrospective and prospective judgments of confidence need to be examined in relation to the clinical phenomenon of impaired SA.