This paper describes recent developments of priming research in cognitive psychology. There are two lines of studies on priming, semantic priming and repetition priming. Semantic priming refers to the phenomenon that the processing of a target stimulus is facilitated by a previously presented prime stimulus that is semantically related or associated with the target. This phenomenon has been investigated to elucidate the organization of semantic memory and the process of word recognition. Recent studies demonstrate that associative priming occurs even when subjects don't identify prime, indicating that semantic processing occurs covertly without subject's awareness. However, there are some controversies over the procedure of covert semantic priming experiment. On the other hand, repetition priming refers to the phenomenon that the processing of a target stimulus is facilitated when the identical stimulus has been previously presented. Word fragment completion task is often used in repetition priming studies, in which subjects are required to fill missing letters to make a word (e. g., ps_ch_lo_y to psychology). The performance of this task is higher for a previously presented word than for a new word. The characteristic of the task is that conscious remembering of previous events is not necessary, while typical memory tests such as recognition and recall test require subjects to recollect past events consciously. The former type of memory test is called implicit memory test, and the latter is explicit memory test. There are many discrepancies between these tests, such that repetition priming found in implicit memory test lasts over a week or a month, though explicit memory test performance declines to a chance level in shorter period. The levels of processing and the modality change influence implicit memory and explicit memory tests differently. These observations suggests the different systems or processes underlie the explicit memory and the implicit memory test performance.

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    We developed a new direct priming task, which contains high familiarity words and low familiarity words, and we perfomed this task to the normal controls (C group), the patients with alcoholics (A group) and the patients with alcohol Korsakoff syndrome (K group )in 30 minutes and 1 week after the presentation of the primer words. Every group demonstrated the priming effects and the priming effect of low familiarity words was larger than that of high familiarity words in C group and A group. The priming effect of high familiarity task demonstrated no statistical differences among C group, A group and K group. However, the priming effect of low familiarity task revealed significantly smaller in K group compared with that in C group and A group. The priming effect was reduced in 1 week in high familiarity task although there was not a significant reduce in low familiarity task. Furthermore, the patients answered correctly in some of the present direct priming task without understanding the meaning of words, suggesting that other factors besides meaning of the words are related to the direct priming effects.

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    Using word completion tasks of KANJI idioms and of proverbs, implicit memory (priming) performance was studied in four groups of subjects : Pick's disease (PD) patients with Gogi (word-meaning) aphasia; PD patients without Gogi aphasia; Alzheimer's disease (AD) patients;healthy controls. Priming performance in the AD group and the PD without Gogi aphasia group was comparable with that in the control group, although those patients could not correctly explain the meanings of idioms and proverbs presented. On the other hand, it was markedly defective in the PD with Gogi aphasia group on both priming tasks and the patients of this group was unaware of idioms and proverbs. In PD patients with Gogi aphasia, phonological sets could not be retrieved even under the implicit condition as a unit of word and of proverb,indicating a disruption of lexicon (phonological representation) in Gogi aphasia regardless an accompanying disruption of semantic system.

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    Recently, Prosopagnosia, inability to recognize visually familiar faces, has been discussed on its heterogenuity. De Renzi (1991) and Benton (1993) classifyed prosopagnosia into apperceptive and associative forms. Covert recognition for familiar faces which had not been identified overtly was revealed in some cases of associative prosopagnosia since the first report by Bruyer et al (1983).
    We reported a case with prosopagnosia and cerebral achromatopsia following bilateral infarction of the posterior cerebral artery territories. Signs of covert face recognition were evidenced in the behavioral methology such as familiar-unfamiliar discrimination task, a test of occupationguess, face-name learning task and multiple forced-choice method. The patient was unable to identify famous faces overtly, but he seemed to have access covertly to semantic code of those faces, e. g. name and / or occupation.
    Covert recognition is a interesting phenomenon which may elucidate a mechanism of prosopagnosia.

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    We administered a task to forty Japanese aphasic patients in which they were to choose the particles to various combination of nouns and verbs, and analyzed the strategies involved in their choices. The task consisted of 233 two-word sentences (noun + particle — verb) in which spaces for the particles were left blank. The subjects were asked to fill in each blank with one from a choice of five particles. The choice of sentences for the task was based on a statistical study of the frequency of use of nouns and noun-particle combinations drawn from a data-base consisting of 494, 956 words of the speech of normal Japanese. The sentences which required the particle “wo” were 76, those which required the particle “kara” were four, those which required the particle “ga” were 67, those which required the particle “de” were 25, and those which required particle “ni” were 30. The remaining sentences allowed more than one particle. Furthermore, in 197 of the sentences the noun phrases represented essential arguments of the verbs, and in 27 the noun phrases represented optional arguments. The subjects were forty chronic aphasic patients of whom fourteen were suffering from Wernicke's aphasia, nine from Broca's aphasia, three mixed, four conduction aphasia, and ten cases of amnestic aphasia.
    Results were as follows. The difficulty in choosing the correct particle was influenced by the frequency of conjunction of noun and particle, as well as by the nature of the argument (essential or optional). Further, it was also influenced by the severity of the comprehension disorder.

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    Recently, various symptoms such as pathological grasp phenomenon and compulsive manipulation of tools have been reported as symptoms associated with lobus frontalis cerebri facies medialis ˜ antero-callosum injury. We happened to experience the case of an 80-years-old woman who exhibited compulsive manipulation of tools by her right hand in addition to aimless, unconscious movements of both hands and right leg, associated with cerebral hemorrhage of lobus frontalis cerebri facies medialis ˜ antero-callosum bilateralis. Her mouth was synergetic with the movement of her right hand, and on bringing a toothbrush to her mouth, the latter opened. The literature on 29 cases revealed 9 cases of hand synkinesia with the mouth and head and 6 cases of non-synkinesia; no definite inclination was found concerning differences according to cases, thus suggesting the head to have a different mode of control from the hands. Our own patient said that her right hand and leg obey word-induced orders, but do not act voluntarily, as compared with her voluntarily-moving left leg. From this finding, the injury of the present case was regarded as an inter- and intra-hemispheric transection, considering that the center of control of the so-called intentional behaviors lies in the right frontal lobe. In addition to specific limb movements, unconscious and aimless movements of the lips, tongue and neck were observed in the course of her disease. These movements were regarded as manifestations of alienlimb-sign in the above sites.

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    We reported a case of Wernicke's aphasia which showed approximately 10 % correct answers in naming of the patient's own family members, in spite of scoring 40 % on the naming task of the Standard Language Test of Aphasia (SLTA). First we suspected so-called “category-specific naming disorder” regarding family members ; however, on a subsequent naming test including 10 other semantic categories, the subject exhibited different severities depending on the semantic category. That is, over 75 % for the category of body parts ; from 25 to 50 % for means of transportation, fruits, vegetables, animals and musical instruments ; and less than 25 % for famous domestic places, family members, fingers and colors. The present study investigated the mechanism underlying the naming disorder by assuming a hierachical structure among semantic categories and applying to it the above results. We concluded that this case's naming disorder is not limited to a specific category but appears with different severities depending on the hierarchical structure of the semantic categories.

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    We present the case of a 74 year-old right-handed man who developed agrammatism following occlusion of the right medial cerebral artery. He had crossed aphasia (Broca's type), left spatial neglect, constructive disorders, left hemianopsia, left hemiparesis and sensory disturbance. He exhibited remarkable agrammatism in speaking, repetition, reading and writing, but showed good word finding, confrontation naming and a rich vocabulary. He did not exhibit any auditory comprehension disorders in daily life and enjoyed listening to the radio daily. His performance on auditory comprehension tasks (The Japanese version of the Western Aphasia Battery and the Token Test) was almost perfect, whereas he showed poor performance for grammatical judgments on sentences including particles like “ga” , “ni” and “wo” . The fact that his performance changed together with the plausibility of the word meaning indicates he had a severe grammatical comprehension disorder. His ability to comprehend sentences using word meaning seems to be based on preservation of his vocabulary. He understood the difference between “Touch the pencil and comb, please” and “Touch the comb with the pencil, please” . This means that he could comprehend some function words, particularly when he understood the verb meaning.

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