title: Measuring consciousness: task accuracy and awareness as sigmoid functions of stimulus duration.
abstract: When consciousness is examined using subjective ratings, the extent to which processing is conscious or unconscious is often estimated by calculating task performance at the subjective threshold or by calculating the correlation between accuracy and awareness. However, both these methods have certain limitations. In the present article, we propose describing task accuracy and awareness as functions of stimulus intensity (thus obtaining an accuracy and an awareness curve) as suggested by Koch and Preuschoff (2007). The estimated lag between the curves describes how much stimulus intensity must increase for awareness to change proportionally as much as accuracy and the slopes of the curves are used to assess how fast accuracy and awareness increases and whether awareness is dichotomous. The method is successfully employed to assess consciousness characteristics on data from four different awareness scales.
authors.affiliation: Cognitive Neuroscience Research Unit, Hammel Neurorehabilitation and Research Center, Aarhus University, Voldbyvej 15, Hammel, Denmark. krissand@rm.dk
authors.forename: Kristian
authors.initials: K
authors.lastname: Sandberg
authors.forename: Bo Martin
authors.initials: BM
authors.lastname: Bibby
authors.forename: Bert
authors.initials: B
authors.lastname: Timmermans
authors.forename: Axel
authors.initials: A
authors.lastname: Cleeremans
authors.forename: Morten
authors.initials: M
authors.lastname: Overgaard
mesh_terms: D001364:Awareness; D003243:Consciousness; D006801:Humans; D010775:Photic Stimulation; D012684:Sensory Thresholds; D013360:Subliminal Stimulation; D013647:Task Performance and Analysis; D014796:Visual Perception