Submillisecond unmasked subliminal visual stimuli evoke electrical brain responses

Subliminal perception is strongly associated to the processing of meaningful or emotional information and has mostly been studied using visual masking. In this study, we used high density 256‐channel EEG coupled with an liquid crystal display (LCD) tachistoscope to characterize the spatio‐temporal d...

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Bibliographic Details
Published in:Human brain mapping 2015-04, Vol.36 (4), p.1470-1483
Main Authors: Sperdin, Holger F., Spierer, Lucas, Becker, Robert, Michel, Christoph M., Landis, Theodor
Format: Article
Language:English
Subjects:
Adult
Brain - physiology
electroencephalography
Electroencephalography - methods
Evoked Potentials, Visual
Female
Humans
Male
Photic Stimulation - instrumentation
Photic Stimulation - methods
Signal Processing, Computer-Assisted
Statistics, Nonparametric
subliminal perception
Subliminal Stimulation
tachistoscope
vision
visual evoked potentials
Visual Perception - physiology
Young Adult
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Summary:Subliminal perception is strongly associated to the processing of meaningful or emotional information and has mostly been studied using visual masking. In this study, we used high density 256‐channel EEG coupled with an liquid crystal display (LCD) tachistoscope to characterize the spatio‐temporal dynamics of the brain response to visual checkerboard stimuli (Experiment 1) or blank stimuli (Experiment 2) presented without a mask for 1 ms (visible), 500 µs (partially visible), and 250 µs (subliminal) by applying time‐wise, assumption‐free nonparametric randomization statistics on the strength and on the topography of high‐density scalp‐recorded electric field. Stimulus visibility was assessed in a third separate behavioral experiment. Results revealed that unmasked checkerboards presented subliminally for 250 µs evoked weak but detectable visual evoked potential (VEP) responses. When the checkerboards were replaced by blank stimuli, there was no evidence for the presence of an evoked response anymore. Furthermore, the checkerboard VEPs were modulated topographically between 243 and 296 ms post‐stimulus onset as a function of stimulus duration, indicative of the engagement of distinct configuration of active brain networks. A distributed electrical source analysis localized this modulation within the right superior parietal lobule near the precuneus. These results show the presence of a brain response to submillisecond unmasked subliminal visual stimuli independently of their emotional saliency or meaningfulness and opens an avenue for new investigations of subliminal stimulation without using visual masking. Hum Brain Mapp 36:1470–1483, 2015. © 2014 Wiley Periodicals, Inc.
ISSN:1065-9471
1097-0193
DOI:10.1002/hbm.22716