title: Keeping it short: a comparison of methods for brief picture presentation.
abstract: Research has shown that backward masking is a powerful tool for studying unconscious mental processes. Whereas studies have traditionally presented stimuli using cathode-ray tube (CRT) monitors or mechanical shutters together with slide projectors, recent studies (mainly in functional magnetic resonance imaging, fMRI) have begun to use methods based on liquid crystal displays (LCDs) and thin-film transistor (TFT) technology. However, because of differences in technology, all methods may not be equally suited for masking. When methods were compared for their accuracy in presenting pictures at short durations, LCD and TFT presentations had poor accuracy, but shutter and CRT presentations had better accuracy. Because CRTs interfere with the imaging process in fMRI, we recommend the use of mechanical shutters. However, our results may not generally apply to all displays, so we advise researchers to validate the presentation parameters of their displays. The procedure described here may be useful for that purpose.
authors.affiliation: Department of Clinical Neuroscience, Karolinska Institute, Stockholm, Sweden. stefan.wiens@cns.ki.se
authors.forename: Stefan
authors.initials: S
authors.lastname: Wiens
authors.forename: Peter
authors.initials: P
authors.lastname: Fransson
authors.forename: Thomas
authors.initials: T
authors.lastname: Dietrich
authors.forename: Peter
authors.initials: P
authors.lastname: Lohmann
authors.forename: Martin
authors.initials: M
authors.lastname: Ingvar
authors.forename: Arne
authors.initials: A
authors.lastname: Ohman
mesh_terms: D003243:Consciousness / Q000502:physiology; D006801:Humans; D010470:Perceptual Masking / Q000502:physiology*; D013997:Time Factors; D014796:Visual Perception / Q000502:physiology*