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Biomedical subjects

Morten Overgaard

Publications and source records attributed to Morten Overgaard.

4 recordsLinked to original sources
PubMed2006

The electrophysiology of introspection.

To study whether the distinction between introspective and non-introspective states of mind is an empirical reality or merely a conceptual distinction, we measured event-related potentials (ERPs) elicited in introspective and non-introspective instruction conditions while the observers were trying to detect the presence of a masked stimulus. The ERPs indicated measurable differences related to introspection in both preconscious and conscious processes. Our data support the hypothesis that introspective states empirically differ from non-introspective states.

Brain↗
PubMed2006

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.

Adolescent↗
PubMed2004

A TMS study of the ventral projections from V1 with implications for the finding of neural correlates of consciousness.

The study of subliminal perception in normal and brain lesioned subjects has long been of interest to scholars studying the neural mechanisms behind conscious vision. Using brief durations and a developed methodology of introspective reporting, we present an experiment with visual stimuli that gives rise to little or no subliminal perception under normal viewing conditions. Coupled with transcranial magnetic stimulation, however, we find a dissociation between correctness and conscious awareness. Furthermore, we find support for the hypothesis that the ventral projection streams from V1 are necessary for visual consciousness.

Adult↗