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
2004. Vol. 15, no 4, 282-5 p.
Consciousness/physiology, Humans, Perceptual Masking/*physiology, Time Factors, Visual Perception/*physiology