Hemispheric Organization of Visual Word Recognition in Turkish Monolinguals

Abstract

Recently obtained data from interdisciplinary research has expanded our knowledge on the relationship between language and the brain considerably. Numerous aspects of language have been the subject of research. Visual word recognition is a temporal process which starts with recognizing the physical features of words and matching them with potential candidates in the mental lexicon. Word frequency plays a significant role in this process. Other factors are the similarities in spelling and pronunciation, and whether words have meanings or are simply letter strings. The emotional load of the words is another factor that deserves a closer inspection as an overwhelming amount of evidence supports the privileged status of emotions both in verbal and nonverbal tasks. It is well-established that lexical processing is handled by the involvement of the brain hemispheres to varying degrees, and that the left hemisphere has greater involvement in verbal tasks as compared to the right hemisphere. Also, the emotional load of the verbal stimuli affects the specialized roles of the brain hemispheres in lexical processing.
 Despite the abundance of research on processing of words that belong to languages from a variety of language families, the number of studies that investigated Turkish, a language of Uralic-Altaic origin, is scarce. This study aims to fill the gap in the literature by reporting evidence on how Turkish words with and without emotional load are processed and represented in the brain. We employed a visual hemifield paradigm and a lexical decision task. The participants were instructed to decide if the letter strings presented either from the right or the left of the computer screen were real words or non-words. Their response times and accuracy of their answers were recorded. We obtained shorter response times and higher accuracy rates for real words than non-words as reported in the majority of studies in the literature. We also found that the emotional load modulated the recognition of words, supporting the results in the literature. Finally, our results are in line with the view of left hemispheric superiority in lexical processing in monolingual speakers.