Neurological Mechanism of Reading

• Project/Area Number: 03451022
• Research Category: Grant-in-Aid for General Scientific Research (B)
• Allocation Type: Single-year Grants
• Research Field: Psychology
• Research Institution: Waseda University
• Principal Investigator: FUKUZAWA Kazuyoshi Waseda University, Associate Professor, 文学部, 助教授 (00156762)
• Co-Investigator(Kenkyū-buntansha): HONMA Daiichi Waseda University, Lecturer, 情報科学研究教育センター, 助手 ; KAWAMURA Mitsuru Showa Medical University, Associate Professor, 医学部・神経内科, 助教授 (20161375)
• Project Period (FY): 1991 – 1992
• Project Status: Completed (Fiscal Year 1992)
• Budget Amount: ¥3,200,000 (Direct Cost: ¥3,200,000); Fiscal Year 1992: ¥200,000 (Direct Cost: ¥200,000); Fiscal Year 1991: ¥3,000,000 (Direct Cost: ¥3,000,000)
• Keywords: neuropsychology / pure alexia / posterior lesion / blurred stimuli / kanji / guessing reading / 周波数特性 / 脳梁膨大 / 右同名半盲

Research Abstract

In order to investigate the neuropsychological mechanism of pure alexia, we proposed a preliminary model for guessing reading of kanji, and tested six hypotheses predicted from the model. The Subjects were four patients with left and right posterior lesions without alexia and two patients with pure alexia. [Hypotheses] (1) Patients without alexia read simple kanji characters better than complex kanji characters. (2) Patients without alexia read concrete kanji characters better than abstract kanji characters. (3) Patients with pure alexia read simple kanji characters better than complex kanji characters. (4) Patients with pure alexia read read concrete kanji characters better than abstract kanji characters. (5) Patients without pure alexia read better than patients with pure alexia. (6) Interaction between the complexity kanji and abstractness of kanji occurs in the subjects'performance. [Stimuli] 27 kanji characters with different blur gradations were used. [Apparatus] AV tachistoscope and a personal computer were used for presenting stimuli. [Procedure] Subjects were required to read all unblurred stimulus kanji characters. Then, subjects were asked to guess the reading of blurred kanji characters When they could not read a given blurred kanji character they were given, another less blurred kanji character. We continued this procedure until subjects read the kanji character. [Results] While hypotheses 1,3,4 and 5 were statistically supported, hypotheses 2 and 6 were not. In other words, pure alexic patients read simple kanji characters better than complex ones, and read concrete kanji characters better than abstract ones. Patients without alexia did not read concrete kanji characters any better than abstract ones. The main effects of kanji complexity, abstractness and presence or absence alexia were statistically significant indicating that patients without alexia read better than pure alexic patients. [Discussion] We assumed the four possible impairment mechanisms in pure alexia based on the preliminary model for guess reading. (1) retrieval of kanji form (2) retrieval of most probable kanji characters which are most closest to the average form of target kanji characters (3) choice of kanji closest to the target (4) reading of the character internally retrieved.