Laterality differences in recognition of Japanese and Hangul words by monolinguals and bilinguals

Two-character nonsense Kana words, individual Kanji words and individual Hangul words are presented tachistoscopically in the left or right visual field to 20 normal, right-handed Japanese students and 13 normal, right-handed Korean subjects. The former did not know Hangul letters. The latter were born and raised in Japan, in exclusively Japanese-speaking families, but they could read Hangul letters and write them a little because they have learned the Hangul language for 6 months. In each of three conditions (Kana, Kanji and Hangul work recognition), each subject was required to move the index finger of his right or left hand leftwards as fast as possible after the presentation of two of four stimuli and rightwards after the presentation of the other two. The reaction time was measured. A significant right field superiority for the recognition of Kana words and no lateral asymmetry for Kanji words were shown in both Japanese and Korean groups. However, for the Hangul recognition, a significant left field superiority for Japanese subjects and a significant right field superiority for Korean subjects were obtained. These findings are interpreted as follows. Kana and Kanji are processed somewhat differently in the cerebral hemispheres. Japanese subjects do not recognize Hangul stimuli as orthographic characters but as shapes or figures. Korean subjects can identify Hangul stimuli as letters. Both the first language (Kana) and second language (Hangul) are processed in the dominant left hemisphere by right-handed Korean subjects.