Varieties of alexia from fusiform, posterior inferior temporal and posterior occipital gyrus lesions

Reading impairments of three alexia patients, two pure alexia and one alexia with agraphia, due to different lesions were examined quantitatively, using Kanji (Japanese morphogram) words, Kana (Japanese phonetic writing) words and Kana nonwords. Kana nonword reading was impaired in all three patients, suggesting that widespread areas in the affected occipital and occipitotemporal cortices were recruited in reading Kana characters (corresponding to European syllables). In addition, the findings in patient 1 (pure alexia for Kanji and Kana from a fusiform and lateral occipital gyri lesion) and patient 2 (pure alexia for Kana from a posterior occipital gyri lesion) suggested that pure alexia could be divided into two types, i.e. ventromedial type in which whole-word reading, together with letter identification, is primarily impaired because of a disconnection of word-form images from early visual analysis, and posterior type in which letter identification is cardinally impaired. Another type of alexia, alexia with agraphia for Kanji from a posterior inferior temporal cortex lesion (patient 3), results from deficient whole-word images of words per se, and thus should be designated "orthographic alexia with agraphia". To account for these impairments, a weighted dual-route hypothesis for reading is suggested.     

Semantic access in number processing investigated with Japanese Kanji and Kana numerals

In number processing, semantic representations are efficiently activated. These representations frequently affect task performance, as demonstrated by semantic effects such as the distance effect (longer reaction times to closer numerical pairs in comparison tasks). The objective of this study was to investigate whether efficient semantic access is a distinctive feature of number processing using the Japanese language. Japanese was chosen to investigate possible effects of ideographic processing and word frequency: Kanji numerals in Japanese are ideograms and are used frequently, while Kana numerals are phonograms and are used infrequently. The results confirmed a distance effect in the numerical and physical matching tasks with both Arabic and Kanji numerals regardless of notation or task (Experiment 1). However, the effect was not observed with the Kana pairs (Experiment 2), thereby suggesting that semantic access is not always efficient in number processing. The results can be explained coherently within a general framework of word recognition by assuming that both the type of character and the word frequency play a critical role in determining the efficiency of semantic access.     

Whole and part comparisons of words and nonwords

Under conditions of sequential presentation, two words are matched more quickly than are a single letter and the first letter of a word. An exception to this whole-word advantage was reported in 1980 by Umansky and Chambers, who used word pairs as stimuli, and asked subjects to compare the entire words or the words’ first letters. Experiment 1 showed that the stimulus lists used by Umansky and Chambers may not have constrained subjects to process the displays differently for wholistic and component comparisons. In those studies, the two words were identical onsame trials for both wholistic and first-letter comparisons, so that first-letter decisions could have been based on wholistic information. In the present study, lists were constructed so that first-letter decisions could not be determined correctly by wholistic information (e.g., BLAME/BEACH), and the whole-word advantage was replicated. Experiment 2 tested whether wholistic comparisons are generally superior to component comparisons. For consonant strings, first-letter comparisons were made more quickly than were whole-string comparisons. These results are interpreted as support for hierarchical models of visual word processing.     

The processing of constituent characters in Kanji words in proofreading Japanese sentences

In two proofreading experiments the processing of constituent characters in Japanese words was studied. In Experiment 1, the subjects were asked to detect misspellings on a CRT displaying a character, a word, a phrase, or a full sentence at a time. In Experiment 2, a comprehension task was added to make sure that the subjects read sentences in left-to right fashion with comprehension. Both experiments showed consistent results. The manipulation of visual similarity between misspelled and correct characters revealed that misspellings having supraletter features nearly identical to the correct characters received lower detection rates, and that the subjects utilized word-level information when proofreading. The disruptive effect on character processing in reading a sentence that was expected from the unitization hypothesis (Healy & Drewnowski, 1983) was not found. The constituent-level units in Japanese words are considered to be functionally equivalent to word-level units, instead of constituting a hierarchy.Part of this research was presented at the Second International Conference on Visual Search, Durham, U.K., September 1990     

Words and hemifields: do the hemispheres enjoy equal opportunity?

A common technique in research into cerebral asymmetry in both normal and clinical populations involves the use of lateralized visual displays. The validity of this approach depends on several generally implicit assumptions about the character of the cognitive processes involved. For example, when words are used as stimuli, cognitive processing is assumed to involve either "whole-word" or "ends-in" analysis. In this way, both hemispheres are assumed to have equal opportunities to recognize the word. These assumptions are critical, because if they are wrong, explanations based on established perceptual principles may provide a sufficient and more parsimonious explanation for hemifield asymmetries than hemispheric specialization theories. This point is developed and illustrated with particular reference to word recognition and classification. From a purely perceptual viewpoint, the right visual field advantage observed in tasks using word stimuli is to be expected given the presence of systematic biases in favor of initial characters or features of words and the relationship between retinal eccentricity and visual acuity. In other words, there is no need nor justification for a hemispheric account of visual field differences in such tasks. Some of the limiting conditions and theoretical implications of this argument are identified and discussed.     

Kanji reading by a prekindergarten language-disabled child: A pilot study

A , severely language-disabled boy was taught 250 words made up of one, two, three, or four Japanese/Chinese kanji. Many kanji words were learned and some ability to process these in simple sentences was observed. Acquisition of a word for meaning was not dependent on its visual complexity, but on the child's ability to grasp the meaning of the word. Results suggest that a whole-word method may facilitate very early reading acquisition and a possible neurophysiological correlate of this is proposed. Kanji or whole words may prove useful for language-handicapped individuals unable to process words phonetically.     

Rapid proportion comparison with spatial arrays of frequently used meaningful visual symbols

It has been shown that when two arrays of Arabic numerals were briefly presented, observers could accurately indicate which array contained the larger number of a target numeral. This study investigated whether this rapid proportion comparison can be extended to other meaningful symbols that share some of notable properties of Arabic numerals. We tested mainly several Japanese Kanji letters, each of which represents a meaning and can work as a word. Using physically identical stimulus sets that could be interpreted as different types of letters, Experiment 1 first confirmed the rapid proportion comparison with Arabic numerals for Japanese participants. Experiment 2 showed that the rapid proportion comparison can be extended to Kanji numerals. Experiment 3 successfully demonstrated that rapid proportion judgments can be found with non-quantitative Kanji letters that are used frequently. Experiment 4 further demonstrated the rapid proportion comparison with frequently used meaningful non-letter symbols (gender icons). The rapid processing cannot be attributed to fluent processing of familiar items, because it was not found with familiar phonograms (Japanese Kana letters). These findings suggest that the rapid proportion comparison can be commonly found with frequently used meaningful symbols, even though their meaning is not relevant to the task.     

Pure agraphia in Romaji after left inferior frontal gyrus infarction: A case of selective deficit in syllable-to-grapheme conversion in Japanese

The Japanese writing system employs two distinct categories of characters: Kana and Kanji. The difference between Kana and Kanji writing corresponds roughly to that between phonological and lexical systems in Western languages. When typing, most Japanese use alphabetical characters based purely on phonological rules. In particular, the Romaji system is used, in which a syllable consists of a single vowel, a consonant–vowel compound (e.g., ka, ki), or a sequence of consonant–y(semivowel)–vowel (e.g., kya, kyu). We describe a right-handed Japanese patient who developed pure agraphia that affected Romaji writing but preserved Kana and Kanji writing and who had a lesion in the left pars opercularis of the inferior frontal gyrus that extended to the anterior precentral gyrus. The patient demonstrated literal paragraphia in spelling Romaji across modalities. Our findings suggested that the patient’s agraphia in Romaji after a confined left frontal infarction was manifested by a selective impairment in syllable-to-grapheme conversion.     

汉字位置加工和词边界效应的认知机制

在中文阅读中, 为了进行词汇识别, 需要对汉字在词中的相对顺序进行加工, 即汉字位置加工。汉字位置加工是词汇识别和阅读理解的重要环节。如果汉字位置未得到加工, 可转置词将很难被区分。可转置词由相同汉字构成, 但每个汉字所处位置不同。以往研究发现, 词内汉字位置加工是比较灵活的; 而且词边界信息会影响汉字位置的加工, 即汉字位置加工存在词边界效应。该效应产生的原因及影响因素有哪些?本项目采用眼动追踪技术, 在自然阅读中系统探讨如下三个问题:(1)词的首/尾汉字如何调节汉字位置加工过程; (2)嵌套词和歧义词边界如何影响汉字位置加工; (3)语境合理性和预测性如何影响汉字位置加工的词边界效应。本项目将为首个中文汉字位置加工模型的建立提供数据支持和科学基础, 推进现有的中文词汇识别和词切分模型的进一步完善, 并为词汇的高效率教授与学习提供科学指导。     

Semantic processing of Arabic,Kanji, and Kana numbers: Evidence from interference in physical and numerical size judgments

Two experiments were conducted with the following objectives (1) to replicate the finding of similar semantic representation of Arabic and written-word (Kanji and Kana) numbers with a direct numerical task, (2) to investigate the automatic semantic processing of Arabic and written-word numbers, and (3) to verify whether the assumption of a common semantic representation is valid in an indirect numerical task. Subjects were asked to judge which of two numbers (e.g, 6-8) was larger either in its numerical size (Experiment 1) or in its physical size (Experiment 2) using the three notations. Effects of two factors were analyzed: the congruity between numerical and physical size and the numerical distance. The effects of these factors were very similar across the three notations in Experiment 1, but were drastically different in Experiment 2. The results of Experiment 2 demonstrated the nonsemantic processing of Kana numbers, and suggest that there may be separate semantic representations for Arabic and Kanji numbers.     

Unilateral agraphia after section of the posterior half of the truncus of the corpus callosum

A Japanese patient who had undergone section of the posterior half of the truncus of the corpus callosum in the process of removing an arteriovenous malformation was examined with a battery of special tests. He showed agraphia only with the left hand (unilateral agraphia). The agraphia was more prominent for the words written in Kana characters (phonograms) than for the words written in Kanji characters (ideograms). The patient showed neither unilateral apraxia, nor tactile alexia, nor tactile anomia.     

LEVEL OF PROCESSING EFFECTS ON HEMISPHERIC ASYMMETRIES WITH KANA (JAPANESE PHONETIC SYMBOLS) WORDS

Two experiments were conducted to examine the role of levels and types of higher-order processing to which the stimulus was subjected. In the experiment 1, two different physical identity matches with Kana (Japanese phonetic symbols) words, one involving two operations while the other involves one operation, were required, and no visual field difference was found though two operations task yielded longer RTs than in one operation task. Experiment 2, where two different name identity matches, one involving linguistic and spatial operations while the other involves linguistic operation, revealed that (1) a significant right visual field advantage is found in the linguistic operation task; however, this tendency disappears in the two operation task, (2) the two operation task yields longer RTs than the one operation task does. These results suggest that the levels of information processing and types of higher-order processing (spatial operation in this study) are important factors in determining hemispheric asymmetry effects.     

编码方式对陌生字形记忆的影响

采用学习-再认范式,分别以韩字、英文假词为实验材料,考察了编码方式对陌生字形记忆的影响。在学习阶段,通过随机呈现整体和部分探测刺激,引导被试分别以整体编码和部分编码方式学习陌生字形,并在学习结束后一小时进行再认记忆测试。结果发现,无论以韩字还是以英文假词为材料,部分编码条件的记忆成绩均显著好于整体编码。该结果说明部分编码相比于整体编码能促进陌生字形记忆,并且这种优势效应具有跨文字系统的一致性。     

The effects of root frequency, word frequency, and length on the processing of prefixed English words during reading

Two experiments were performed to investigate the roles of root morpheme frequency and word frequency in the encoding of prefixed words in sentence context. Two alternative words, which were equated on other indices but differed with respect to either root morpheme frequency or word frequency, were embedded in the same sentence frame. In Experiment 1, there was a significant root morpheme frequency effect on gaze duration but only a marginal word frequency effect. Post hoc analyses indicated that word length influenced both effects, with word frequency effects predominating for shorter words and root morpheme effects predominating for longer words. In Experiment 2, word length was also manipulated. There was a significant root frequency effect for longer prefixed words and a significant word frequency effect for shorter prefixed words. The results were best explained by a dual-route model (with competing whole-word access and compositional routes), in which increasing word length inhibited the whole-word process, relative to the compositional route.     

Are letter codes always activated?

This investigation assesses whether a word’s constituent-letter codes are activated when whole-word processing is encouraged, as well as when letter processing is encouraged. In Experiments 1 and 2, word primes were followed by a target item that had to be named. The target was a word, a constituent letter that had appeared in the prime, or a nonconstituent letter that had not appeared in the prime. The measure of constituent-letter activation was the difference in letter-naming latency between constituent and nonconstituent letters. Presumably, if constituent letters are named faster, letters are being activated by the words in which they appear. To encourage either whole-word or letter analysis during the processing of the priming word, the proportion of word versus letter targets was systematically varied. When the proportion heavily favored letter targets, constituent letters were named faster than their nonconstituent controls. However, a constituent-letter (vs. a nonconstituent-letter) advantage was not obtained when the proportion favored word targets. Experiment 3 replicated the effect with a priming task that required a discrimination response, instead of a naming response. Thus the results suggested that the activation of constituent-letter codes need not take place during the processing of words, but occurs only when letter analysis is stressed by the task.