Poster B76, Tuesday, August 20, 2019, 3:15 – 5:00 pm, Restaurant Hall
The role of attention in visual language information processing
Iuliia Lamekina1, Yury Shtyrov1,2, Andriy Myachykov1,3, Sara Liljander4;1Natonal University - Higher School of Economics, 2Aarhus University, 3Northumbria University, 4Aalto University
Automaticity in language processing has been a debated issue in recent decades. Previous data from auditory experiments is consistent with the biased competition model of attention: strong connections within lexical circuits determine activation that is largely independent of the level of attention/inhibition. In contrast, pseudowords activate several circuits partially - the activity is dependent on the inhibition level. However, no experiments with control for attention (two conditions) in visual modality, as well as with investigation of early semantic processing, have been conducted before. Moreover, there exists a consistent controversy as to timing and localisation of automated responses. We conducted an experiment with 128 EEG channels recording. The stimuli were in Russian and included matched words vs. pseudowords vs. non-words as controls. Words sample also was aimed at studying embodied semantics: 100 action vs. 100 non-action words. The task was to find on the screen either a specific letter combination (attend condition) or color pattern (non-attend). We predicted stable activation for words, regardless of attention, activation for pseudowords dependent on attention, and differences in response localisation: action words would induce additional activation in sensorimotor cortex. The results of our experiment indicate that visual symbol processing comprises three stages : 140 (pre-attentive/automatic), 240 (attentional) and 300 ms (reprocessing). Visual modality differs from auditory: due to strong effect of attention, differences between attend and non-attend conditions were higher than between lexical/non-lexical units. However, our first hypothesis was still valid: at 140 and 300 ms, the responses for words had smaller range than for pseudowords, and this lexicality effect was statistically significant. There was also evidence for early semantic processing at 140 ms and reprocessing at 300 ms. As to the topographic results, we found that attended stimuli exhibit strong central negativity and occipital positivity at 240 and 300 ms. Both words and pseudowords elicited fronto-temporal right and left-biased negative responses in non-attend condition and more central responses in attend; for non-words, the pattern was reversed. Occipital positivity was characteristic for visual modality (but not for non-attend condition at 140 ms). As well as that, additional activation in motor cortex for action words was found. Our results support hypothesis for more stable activation for words at 140 and 300 ms. In general, our study confirms the multi-stage processing model, the intervals being in line with previous studies. Nevertheless, we didn’t find any significant traces of “ultra-rapid” lexical activation (around 30-70 ms), due either to vulnerability of these earlier peaks or to the lack of response. The topographic results, while consistent with the traditional account for linguistic processing in left frontal and temporal regions, also provide evidence for activation in the right hemisphere, and suggest a distributed network of language processing. The additional activation in motor cortex for action words is in line with the embodied semantics hypothesis.
Themes: Speech Perception, Reading
Method: Electrophysiology (MEG/EEG/ECOG)