engleski

Pseudoword Processing: Two Types of Pseudowords in an 3-timulus Oddball Paradigm

Lexical access is the way in which an individual accesses word located in his/her mental lexicon. In the explanation of the processes underlying this access, neuroimaging studies are highly valuable since they provide insights into temporal and/or spatial dimension of these processes by using different paradigms with linguistic stimuli (e.g. words and pseudowords). The aim of this study is to investigate both unattended and task related language processing using event-related potentials (ERP) in a 3- stimuli oddball paradigm with two types of pseudowords (phonological and orthographic) stimuli when the attention is moved from lexical to semantic decision. Certain aspects of the words such as visual and phonological properties were modulated using pseudowords, expecting that their effect will be more prominent in early phases of word processing, while semantic and task related properties will show differences between words and pseudowords in later phases. In total, 19 adult Croatian native speakers (F=12 ; M=7) were included in the study.Recording was performed using BrainVision Recorder software and Brain Products QuickAmp136 amplifier with actiCAP containing 32 active electrodes. The experimental task was the semantic decision task in which the participants had to press the button each time the displayed word belonged to a specific semantic category (animal/food). The obtained results show marginal ERP difference between phonological and orthographic pseudowords considering the latency of N400 component for the phonological pseudowords, which can be interpreted as prolonged processing. Prominent ERP differences can be observed in later phases for all three main groups (control word, target and pseudoword). Strong P600 can be observed for the pseudowords despite the fact that they were not in the focus of the attention. Also quite clear distinction between P3b for the target group and P600 for two the pseudoword groups has been found. P3b for words is a strong frontal component that starts around 300 ms, reaches its peak at 550 m and it has a different latency then P600. The obtained results didn't show any significant difference in early ERP response regarding two types of pseudowords.

lexical processing, pseudowords, ERP

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