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Subword Representations Successfully Decode Brain Responses to Morphologically Complex Written Words

delete2024-09-11
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OA
AI
T
Tero Hakala
T
Tiina Lindh‐Knuutila
A
Annika Hultén
M
Minna Lehtonen
R
Riitta Salmelin *
DOI:10.1162/nol_a_00149delete
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Abstract

Abstract

En 中文
This study extends the idea of decoding word-evoked brain activations using a corpus-semantic vector space to multimorphemic words in the agglutinative Finnish language. The corpus-semantic models are trained on word segments, and decoding is carried out with word vectors that are composed of these segments. We tested several alternative vector-space models using different segmentations: no segmentation (whole word), linguistic morphemes, statistical morphemes, random segmentation, and character-level 1-, 2- and 3-grams, and paired them with recorded MEG responses to multimorphemic words in a visual word recognition task. For all variants, the decoding accuracy exceeded the standard word-label permutation-based significance thresholds at 350-500 ms after stimulus onset. However, the critical segment-label permutation test revealed that only those segmentations that were morphologically aware reached significance in the brain decoding task. The results suggest that both whole-word forms and morphemes are represented in the brain and show that neural decoding using corpus-semantic word representations derived from compositional subword segments is applicable also for multimorphemic word forms. This is especially relevant for languages with complex morphology, because a large proportion of word forms are rare and it can be difficult to find statistically reliable surface representations for them in any large corpus.
Keywords:
decoding
MEG
multimorphemic words
statistical morphemes
word2vec

Journal

N
Neurobiology of Language
IF:
3.1
Papers:
159
Citations:
441

Organization

A
Aalto University
Scholars:
1.6W
Papers: 1.5W
Citations: 2.1W
U
University of Turku
Scholars:
1.7W
Papers: 1.5W
Citations: 2.0W
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