Is conscious perception gradual or dichotomous? A comparison of report methodologies during a visual task

In a recent article, [Sergent, C. & Dehaene, S. (2004). Is consciousness a gradual phenomenon? Evidence for an all-or-none bifurcation during the attentional blink, Psychological Science, 15(11), 720-729] claim to give experimental support to the thesis that there is a clear transition between conscious and unconscious perception. This idea is opposed to theoretical arguments that we should think of conscious perception as a continuum of clarity, with e.g., fringe conscious states [Mangan, B. (2001). Sensation's ghost-the non-sensory "fringe" of consciousness, Psyche, 7, 18]. In the experimental study described in this article, we find support for this opposite notion that we should have a parsimonious account of conscious perception. Our reported finding relates to the hypothesis that there is more than one perceptual threshold [Merikle, P.M., Smilek, D. & Eastwood, J.D. (2001). Perception without awareness: perspectives from cognitive psychology, Cognition, 79, 115-134], but goes further to argue that there are different "levels" of conscious perception.