Implicit awareness in anosognosia: clinical observations, experimental evidence, and theoretical implications

Unawareness  of deficits caused by brain damage or neurodegeneration, termed anosognosia, has been demonstrated in a number of different neurological conditions. Clinical observation suggests that unawareness paradoxically can be accompanied by signs of understanding or representation of deficit, but not explicitly expressed. Such "implicit awareness," an apparent oxymoron, is implied by or inferred from actions or statements of the person with neurological disorder. In the current paper, we review clinical observations and experimental evidence which suggest the occurrence of implicit awareness in dementia and hemiplegia, and explore the clinical and theoretical implications of this phenomenon. We present a theoretical framework to understand implicit awareness in these two conditions.