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Subliminal Word Processing: EEG Detects Word Processing Below Conscious Awareness

The present electroencephalography (EEG) study observed how the brain processes visual stimuli (words and shapes) displayed with four different duration times (17 ms, 33 ms, 67 ms, and 100 ms). All stimuli had to be classified into “I saw nothing”, “I saw a blur”, “I saw a word,” or “I saw a shape”...

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Autores principales: Pavlevchev, Samuil, Chang, Minah, Flöck, Alessandra Natascha, Walla, Peter
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9026434/
https://www.ncbi.nlm.nih.gov/pubmed/35447996
http://dx.doi.org/10.3390/brainsci12040464
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author Pavlevchev, Samuil
Chang, Minah
Flöck, Alessandra Natascha
Walla, Peter
author_facet Pavlevchev, Samuil
Chang, Minah
Flöck, Alessandra Natascha
Walla, Peter
author_sort Pavlevchev, Samuil
collection PubMed
description The present electroencephalography (EEG) study observed how the brain processes visual stimuli (words and shapes) displayed with four different duration times (17 ms, 33 ms, 67 ms, and 100 ms). All stimuli had to be classified into “I saw nothing”, “I saw a blur”, “I saw a word,” or “I saw a shape” via distinct button presses while brain potentials were being measured. The neurophysiological correlates of word and shape processing were subsequently analysed and compared for two distinct time points at the occipito-parietal area in both hemispheres (P7 and P8). In a further step, word and shape identification rates were also analysed. Identification rates revealed that participants recognized words and shapes when presented for 17 ms at a rate of only 6% and 7%, which is poor enough to assume an overall lack of conscious recognition. Analysis of EEG data revealed two time points of interest, one at 210 ms and the other at 280 ms post stimulus onset. Brain potentials at the earlier time point reflect modulations in presentation duration with increased amplitudes elicited by longer presentations. At this time point, no differences were seen between words and shapes in both hemispheres. The later time point, though, clearly distinguished between word and shape processing with totally missing amplitudes (i.e., brain activity) in the case of shapes in general in both hemispheres. Crucially, words presented for only 17 ms still elicited an average brain potential amplitude significantly different from the corresponding 17 ms presentations of shapes at this time point at electrode location P7, even though both stimuli categories were basically not seen (i.e., not consciously recognized). This later word-specific brain potential for the shortest presentation duration is interpreted as neurophysiological evidence of subliminal word processing. Strikingly, this difference was not found in the right hemisphere at P8.
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spelling pubmed-90264342022-04-23 Subliminal Word Processing: EEG Detects Word Processing Below Conscious Awareness Pavlevchev, Samuil Chang, Minah Flöck, Alessandra Natascha Walla, Peter Brain Sci Article The present electroencephalography (EEG) study observed how the brain processes visual stimuli (words and shapes) displayed with four different duration times (17 ms, 33 ms, 67 ms, and 100 ms). All stimuli had to be classified into “I saw nothing”, “I saw a blur”, “I saw a word,” or “I saw a shape” via distinct button presses while brain potentials were being measured. The neurophysiological correlates of word and shape processing were subsequently analysed and compared for two distinct time points at the occipito-parietal area in both hemispheres (P7 and P8). In a further step, word and shape identification rates were also analysed. Identification rates revealed that participants recognized words and shapes when presented for 17 ms at a rate of only 6% and 7%, which is poor enough to assume an overall lack of conscious recognition. Analysis of EEG data revealed two time points of interest, one at 210 ms and the other at 280 ms post stimulus onset. Brain potentials at the earlier time point reflect modulations in presentation duration with increased amplitudes elicited by longer presentations. At this time point, no differences were seen between words and shapes in both hemispheres. The later time point, though, clearly distinguished between word and shape processing with totally missing amplitudes (i.e., brain activity) in the case of shapes in general in both hemispheres. Crucially, words presented for only 17 ms still elicited an average brain potential amplitude significantly different from the corresponding 17 ms presentations of shapes at this time point at electrode location P7, even though both stimuli categories were basically not seen (i.e., not consciously recognized). This later word-specific brain potential for the shortest presentation duration is interpreted as neurophysiological evidence of subliminal word processing. Strikingly, this difference was not found in the right hemisphere at P8. MDPI 2022-03-30 /pmc/articles/PMC9026434/ /pubmed/35447996 http://dx.doi.org/10.3390/brainsci12040464 Text en © 2022 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Pavlevchev, Samuil
Chang, Minah
Flöck, Alessandra Natascha
Walla, Peter
Subliminal Word Processing: EEG Detects Word Processing Below Conscious Awareness
title Subliminal Word Processing: EEG Detects Word Processing Below Conscious Awareness
title_full Subliminal Word Processing: EEG Detects Word Processing Below Conscious Awareness
title_fullStr Subliminal Word Processing: EEG Detects Word Processing Below Conscious Awareness
title_full_unstemmed Subliminal Word Processing: EEG Detects Word Processing Below Conscious Awareness
title_short Subliminal Word Processing: EEG Detects Word Processing Below Conscious Awareness
title_sort subliminal word processing: eeg detects word processing below conscious awareness
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9026434/
https://www.ncbi.nlm.nih.gov/pubmed/35447996
http://dx.doi.org/10.3390/brainsci12040464
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