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Introduction: The cognitive, emotional and behavioural alterations secondary to acquired brain injury and degenerative dementias can be quantitatively and quantitatively appraised by administering self-reports that ask both patients and reliable informants about the difficulties patients have in their everyday life., Subjects and Methods: The Prefrontal Symptoms Inventory (PSI) and the Modified Memory Failures in Everyday Life Questionnaire (MFE-30) were administered to 174 paired participants: 87 patients with brain damage or degenerative dementias and their 87 reliable informants. In addition to the psychometric goodness of the tests, the study also explored the clinical usefulness of applying these questionnaires to patients and their informants in order to obtain a rate of discrepancy in the scores as a measure of anosognosia., Results: The results show how applying the PSI-20 (20 items) or the PSI (46 items), whether administered together with the MFE-30 (30 items) or not, is a very useful procedure for assessing the symptoms in individuals with acquired brain injury or degenerative dementias, since it yields a great deal of information about patients' difficulties in their daily life., Conclusions: We recommend that, in addition to the compulsory neuropsychological assessment, questionnaires or inventories of symptoms like those proposed here should be carried out, due to the fact that they offer a number of advantages from the clinical point of view, as well as being efficacious and effective in economic terms.

Unawareness of the diseases or its consequences can be a protective mechanism against a traumatic event. However, it can also result in dangerous behaviors and hamper the care management. Still not well understood, unawareness is a very complex and multidimensional construct involving neurological, neuropsychological, psychopathological and psychosocial dimensions. Sometimes considered to be a categorical phenomenon, unawareness is actually partial and dimensional. Nevertheless, no or only weak correlation are found between the results of various methods used to its assessment. We propose that the usual opposition between neurological (anosognosia) and psychopathological (denial) conceptions should be replaced by an integrative approach of the various dimensions involved in unawareness to allow a better adaptation of the care management.

Patients with bilateral parieto-occipital brain damage may show intact processing of individual objects, while their perception of multiple objects is disturbed at the same time. The deficit is termed 'simultanagnosia' and has been discussed in the context of restricted visual working memory and impaired visuo-spatial attention. Recent observations indicated that the recognition of global shapes can be modulated by the spatial distance between individual objects in patients with simultanagnosia and thus is not an all-or-nothing phenomenon depending on spatial continuity. However, grouping mechanisms not only require the spatial integration of visual information, but also involve integration processes over time. The present study investigated motion-defined integration mechanisms in two patients with simultanagnosia. We applied hierarchical organized stimuli of global objects that consisted of coherently moving dots ('shape-from-motion'). In addition, we tested the patients' ability to recognize biological motion by presenting characteristic human movements ('point-light-walker'). The data revealed largely preserved perception of biological motion, while the perception of motion-defined shapes was impaired. Our findings suggest separate mechanisms underlying the recognition of biological motion and shapes defined by coherently moving dots. They thus argue against a restriction in the overall capacity of visual working memory over time as a general explanation for the impaired global shape recognition in patients with simultanagnosia.

A review of published brain-damaged patients showing delusional beliefs concerning the contralesional side of the body (somatoparaphrenia) is presented. Somatoparaphrenia has been reported, with a few exceptions, in right-brain-damaged patients, with motor and somatosensory deficits, and the syndrome of unilateral spatial neglect. Somatoparaphrenia, most often characterized by a delusion of disownership of left-sided body parts, may however occur without associated anosognosia for motor deficits, and personal neglect. Also somatosensory deficits may not be a core pathological mechanism of somatoparaphrenia, and visual field disorders may be absent. Deficits of proprioception, however, may play a relevant role. Somatoparaphrenia is often brought about by extensive right-sided lesions, but patients with posterior (parietal-temporal), and insular damage are on record, as well as a few patients with subcortical lesions. Possible pathological factors include a deranged representation of the body concerned with ownership, mainly right-hemisphere-based, and deficits of multisensory integration. Finally, the rubber hand illusion, that brings about a bodily misattribution in neurologically unimpaired participants, as somatoparaphrenia does in brain-damaged patients, is briefly discussed.

The present study investigated the types of inaccurate responses, i.e., Don't Know, Semantic, Visual (nonlinguistic), Phonological, Circumlocutory, and Perseverative, made on the Hooper Visual Organization Test by a heterogeneous sample of 68 brain-damaged and 63 substance abuse patients. The mean age of the brain-damaged and substance abuse groups were 46.0 (SD=13.5) and 43.7 (SD=12.9) yr., respectively. Analysis showed that the brain-damaged group made significantly more visual and perseverative responses than the substance abuse group. There was significantly more variance in the Visual responses than the Semantic responses for the brain-damaged group. The authors conclude that visuospatial ability is the primary factor for successful performance on this test.

GP, a right-handed woman, without evidence of familial left-handedness, showed clearcut bilateral ideo-motor apraxia and oro-facial apraxia after a vascular lesion of the right hemisphere, encroaching upon the fronto-mesial region. She scored normally in most other cognitive tests, including language, but showed signs of callosal disconnection, left anarchic hand and mild unilateral spatial neglect. This cognitive profile points to the possibility of praxis being localized to the right hemisphere in this right-handed patient. We argue in favour of individual variability of praxis dominance, and maintain that this dominance might be completely right-sided in some subjects. Moreover the anatomical locus of GP's lesion points to the possible role that the frontal lobes (and more specifically the Supplementary Motor Area) play in the genesis of apraxia.

Cognitive neuropsychology has been used successfully in the analysis of adult neuropsychological disorders in both verbal and nonverbal domains. When applied to children, it aims to construct models on the basis of functional lesions manifest within developing systems and provides a theoretical framework within which patterns of intact and deficient skills can be charted over time. These patterns constrain possible underlying models. In highlighting potential individual differences in the acquisition of skills and indicating intact skills within subjects, cognitive neuropsychology may also enable a precise description of the locus of difficulty and potential circumventory routes for remediation around it. The theoretical assumptions of cognitive neuropsychology and issues relevant to its methodology are discussed, including the terminology and principles of modularity, the significance of individual differences and the use of case studies, the dynamics of developing systems, current views on plasticity, and distinctions between developmental and acquired disorders. The application of cognitive neuropsychology to children is discussed in relation to three cognitive areas: face recognition disorders, language disorders and arithmetical disorders. These illustrate the similarities that there are between many developmental cognitive neuropsychological disorders and those seen in adults following brain injury. Models derived from studies of adults are helpful in enabling understanding of both face recognition disorders and arithmetical disorders in childhood. Within language systems, a variety of different types of disorder are evident, which not only relate to receptive and productive difficulties but differentially affect the core components of the language system. All of the disorders discussed illustrate the limitations of functional plasticity in development. In each case, there is not a generalised deficit resulting from degradation of capabilities independent of task requirements. Rather, there are focal and selective disorders which affect subcomponents of cognitive systems. In some cases, genetic factors may constrain compensatory mechanisms.

This study was designed to investigate the role of visual sensory deficits and neglect in perceptual categorization deficits in a group of 35 patients with unilateral cerebral lesions. From theoretical point of view, it was expected that right hemisphere lesions would play a critical role in eliciting perceptual categorization deficits which could not be accounted for by visual sensory deficits or neglect. The results revealed that perceptual categorization deficits were not confined to RHD patients, but they were also found in LHD patients. RHD patients were impaired regardless of the nature of the task (verbal vs. nonverbal), while LHD patients were impaired on nonverbal tasks, and in a lesser degree on verbal tasks. In both braindamaged groups, perceptual categorization deficits were highly associated with visual sensory deficits, however, perceptual categorization deficits were also found without impairments in the visual sensory system. Neglect to be less important determinant of perceptual categorization deficits. The present findings are discussed in the light of Warrington's model of object agnosia.

A brain-damaged patient with prosopagnosia and a group of age- and education-matched control subjects evaluated curved and straight versions of different sorts of stimuli in different tasks. The patient consistently required more time to encode curved than straight stimuli, relative to the control subjects. Specifically, he had a deficit when he compared curved lines that were simultaneously visible, when he compared curved lines with those previously seen, when he examined a curved shape to determine whether an X was on or off the shape, and when he read curved script. He also made more errors when he named pictures of curved objects. Implications of these findings for some types of clinical disorders and for the role of "end-stopped" cells in visual cortex are discussed.

In this study we report our investigations of a category specific visual associative agnosia. The patient D.R.S.'s spoken language skills were excellent. Although he could name objects from their description, he was unable to name them by sight nor was he able to mime their use. On visual-visual matching tasks his performance was impaired and affected by semantic proximity. In two tasks his knowledge of visual objects was demonstrated to be significantly more impaired than his knowledge of visual living things. It is argued that these findings support a multiple knowledge base hypothesis.

A patient with bilateral parietal damage, and Balint's syndrome, named visual letters. These were presented individually or within four-letter strings. Solitary letters were identified very accurately. In the case of strings, more letters were correctly reported for words than for nonwords, and more for pronounceable than for unpronounceable nonwords. When required to read words as a whole, performance was better than predicted by letter-reports. These results extend the object-based limitation apparent in Balint's syndrome to the case of reading. The component letters of a string benefit when they form a familiar global object, rather than requiring representation as multiple separate objects. The patient occasionally made homophonic errors when listing the letters in a visual word. This suggests an attempt to bypass visual simultanagnosia by treating the string as a single object, deriving a holistic phonological code for it, and then decomposing this into component letters via spelling rules.

This is a case-study of a patient (ET) who suffers from prosopagnosia, in the context of impairment to cognitive functions, following traumatic brain injury. Despite severe perceptual difficulties in tests involving non-face stimuli and matching unfamiliar faces, ET showed evidence of "covert" recognition of familiar faces in a number of tasks. Although densely prosopagnosic, she performed at normal levels in word and object recognition tasks, and is unimpaired in her ability to recognise names of celebrities. She performed at the same level as controls in her ability to make a forced-choice of the correct name for a famous face, even though it evoked no feeling of familiarity for her. She performed at chance in a forced-choice face familiarity decision task, but showed evidence of covert recognition in a "true" versus "untrue" face-name learning task. ET showed overt recognition of some famous faces using a procedure based on Sergent and Poncet's (1990) semantic activation task. The pattern of impairment of ET's face processing abilities is interpreted in terms of an interactive activation model of face processing.

Disagreement over the neuroanatomical substrate of associative visual agnosia encompasses such basic issues as: (1) the necessity for bilateral lesions; (2) the intrahemispheric locus of damage; and (3) the roles of disconnection versus cortical damage. We examined three patients whose associative visual agnosia encompassed objects and printed words but spared faces. CAT scans revealed unilateral dominant occipitotemporal strokes. CAT scans of four previously reported cases with this same profile of associative agnosia were obtained. Dominant parahippocampal, fusiform and lingual gyri were the most extensively damaged cortical regions surveyed and were involved in all cases. Of white matter tracts surveyed, only temporal white matter including inferior longitudinal fasciculus was severely and universally involved. Splenium of the corpus callosum was frequently but not always involved. We conclude there is a form of associative visual agnosia with agnosia for objects and printed words but sparing face recognition which has a characteristic unilateral neuropathology. Damage or disconnection of dominant parahippocampal, fusiform and lingual gyri is the necessary and sufficient lesion.

A case of tool use disturbance without impairment of motor skills and of conceptual knowledge of how tool must be used is reported. The patient could not manipulate objects isolatedly or in succession but could pantomime their use on command and on imitation. This finding suggests that manipulation of objects may dissociate from pantomime without objects. We interpret this syndrome as a results of mismatch of tool and tool use.

Following a trauma that mainly involved the right hemisphere, a 21-year-old girl showed a profound impairment in visual object recognition, without language and intellectual deficit. Her elementary sensory functions were preserved and she performed in the normal range on visual matching tasks, on taks requiring to detect small differences between similar complex shapes and in copying drawings, without any evidence of a line by line approach. Her deficit emerged with tests that, though not implying identification of meaning, demanded to disentangle a form from a confused background and to achieve a highly structured description of the stimulus. In addition to this high-level perceptual processing disorder, there was a deficit in recovering from the visual store the shape of an object, also when the performance did not involve perceptual discrimination, e.g., in drawing from memory or telling the physical difference between two named stimuli. Knowledge of the semantic and contextual attributes of objects was intact. The case is taken as evidence that the borders of apperceptive agnosia may be ampler than usually thought and its distinction from associative agnosia less rigid, with some patients laying in-between the two syndromes.

Individuals suffering from misidentification syndromes may present with right hemispheric pathology and deficits in facial recognition. In addition, misidentification delusions have been associated with aggressive behaviour. The possible linkage between misidentification phenomena, facial recognition, and aggression is discussed, illustrated by the case of a patient suffering from an organic delusional disorder.

The revised Neuropsychological Impairment Scale (NIS) is a 95-item, self-reporting screening measure of neuropsychological symptoms. The present report examines the concurrent validity and test-retest stability of the NIS with a neurologically stable sample. The validation study found higher than chance correlations between the NIS and the validity battery and higher correlations with tests that are more sensitive to cognitive impairment. Results also suggest that patients may have more accurate awareness of certain areas of cognitive functioning (academic skills, speech/language functioning) than others (memory, attention, higher level problem-solving). High stability correlations over 2 to 3 months suggest that the NIS measures persisting characteristics rather than temporary states.

A case is reported of an associative visual agnosic patient who could not draw from memory objects he could recognize, even though he could copy drawings flawlessly. His ability to generate mental visual images was found to be spared, as was his ability to operate upon mental images. These data suggest that the patient could generate mental images but could not draw from memory because he did not have access to stored knowledge about pictorial attributes of objects. A similar functional impairment can be found in some other visual agnosic patients and in patients affected by optic aphasia. The present case allows a discussion of relationships among drawing from memory, imagery, and copying procedures.

Dissociation between personal and extrapersonal neglect has rarely been observed in man. In this study we present a case of severe personal neglect in the absence of a deficit for extrapersonal space. An extensive neuropsychological assessment demonstrates the absence of cognitive impairments in visuo-spatial processing and confirms the selective presence of a severe representational deficit of the left side of the body.

Hom and Reitan (1982) reported findings with respect to sensorimotor deficits in groups with lateralized cerebral lesions, but evaluated the results only within a framework that related cerebral dominance to deficits that resulted from lateralized lesions. Some of the variables they studied, however, depend upon evidence of retention of functions by one hemisphere under conditions of distracting input. While the right cerebral hemisphere appears to be dominant for tactile-perceptual abilities in terms of resulting deficits, the present study suggests that the left cerebral hemisphere is dominant for certain non-language functions that reflect maintenance of sensory-perceptual abilities under conditions of distracting stimuli.

Two patients with tactile naming disorders are reported. Case 1 (right hand tactile agnosia due to bilateral cerebral infarction) differentiated tactile qualities of objects normally, but could neither name nor categorize the objects. Case 2 (bilateral tactile aphasia after operation of an epidural left parietal haematoma) had as severe a tactile naming disturbance as Case 1, but could categorize objects normally, demonstrating that tactile recognition was preserved. Case 1 may be the first case of tactile agnosia clearly differentiated from tactile aphasia. CT scans of Case 1 revealed lesions in the left angular gyrus, and in the right parietal, temporal, and occipital lobes. Case 2 had lesions in the left angular gyrus and of posterior callosal radiations. Our findings suggest that tactile agnosia appears when the somatosensory association cortex is disconnected by a subcortical lesion of the angular gyrus from the semantic memory store located in the inferior temporal lobe, while tactile aphasia represents a tactual-verbal disconnection.

Experiments were designed to examine the imagery abilities of an agnosic patient, M.S., who has consistently shown more severe deficits in recognizing visually, and in retrieving knowledge of living as compared with non-living items. Judgements of visual similarity were required for named objects and for object-pictures, as well as for the factual properties of these stimuli. The same disproportionate difficulty in processing living ('natural') objects was found in these tasks as well as in forced-choice recognition. In contrast, no deficit was found on analogous tasks concerned with word-shape similarities. These findings have a bearing on concepts of semantic memory.

In a previous report, Bauer (1984) described the patient LF, who was unable to recognise familiar faces. Despite the inability to verbally identify familiar faces, psychophysiological examination revealed preserved covert processing of facial identity. Subsequent studies have demonstrated covert face recognition using behavioural tasks. Investigations of the patient PH showed normal face familiarity effects on matching, interference, priming, and learning tasks, while overt recognition was completely absent (De Haan, Young and Newcombe, 1987b). The use of different methodologies has led to different theoretical conceptualisation of the "covert recognition" phenomenon. Until now, no individual patient has been exposed to both methodologies. In this study we evaluated LF, who shows psychophysiological evidence of covert recognition, using behavioural tasks previously used with PH. The results reveal clear behavioural evidence of preserved face recognition without awareness. These findings suggest that both methodologies tap similar phenomena, and have important implications for theoretical models of covert face recognition. A conceptual model designed to integrate psychophysiological and behavioural evidence of covert face recognition is proposed.

Lesions producing pure topographical disorientation syndromes are classically located either in the right parietal region either in the right parahippocampal gyrus. The patient described in the present study was admitted to hospital after sudden onset of a left hemiparesis. The lesion at CT scan was located in the posterior limb of the right internal capsule. Neuropsychological assessment was normal except for the presence of a major topographical disorientation and of mnestic disturbances for visuo-spatial material leading us to attribute topographical disorientation to a specific loss of topographical memory. Regional cerebral blood flow measurements disclosed a right parietal hypoperfusion. This remote cortical effect could account for the presence of the neuropsychological disorders.

Brain damage sometimes seems to impair recognition of living things, despite relatively preserved recognition of nonliving things. The most straightforward interpretation of this dissociation is that the recognition of living things depends on some specialized mechanisms that are not needed for the recognition of nonliving things. However, there are alternative interpretations of the dissociation in terms of the greater complexity or inter-item similarity of living things, or the more specific, within-category identifications that are usually required for living things. Surprisingly, the relevant tests to discriminate among these rival hypotheses have never been performed. We took the factors of visual complexity, inter-item similarity, specificity of identification, as well as others, into account in analyzing the visual recognition performance of two head-injured visual agnosic patients. In each case we found that recognition of living things was still disproportionately impaired when the effects of the other factors were accounted for.

Pure word deafness, usually involving left hemisphere focal lesions that destroy Heschl's gyrus and/or isolate auditory association cortex, may be rare, but cases with additional perceptual or cognitive symptoms may not be. Word deafness can be transient or evolving, and has been seen in various conditions without identifiable focal lesions. Only two closed head injury cases with focal contusions have been reported; we report two more, with diffuse damage and no focal signs. One patient's symptoms evolved soon after they were recognized. The other patient's unresponsiveness to spoken verbal stimuli persisted despite relatively preserved reading and speech, in a context of poor initiation and moderately severe cognitive impairment. Unrecognized, word deafness following head injury could lead to overestimation of coma duration if transient, and impede rehabilitation if chronic.

Four neglect patients are reported who where unable to detect left-side differences in pairs of drawings though being sometimes influenced by such differences in making preference judgements. In most instances, tracing the silhouette of the drawings did not help patients to find the difference despite the fact that tracing implied crossing the altered detail or following its contour with the fingertip. This finding cannot easily be accommodated by current theories of unilateral neglect.

Although a systematic cognitive neuropsychology of awareness has not yet emerged, a number of phenomena reported in the literature provide an empirical basis for developing it. The present discussion focusses on two such phenomena: implicit knowledge, which refers to knowledge that is expressed in task performance unintentionally and with little phenomenal awareness; and anosognosia, which refers to unawareness of neuropsychological deficits. Two types of theoretical accounts of these phenomena are discussed. A first order theoretical account entails postulating damage to, or disconnection of, a system or process that generates awareness across multiple domains. A second-order account does not postulate disruption of a cross-domain awareness mechanism, but instead appeals to difficulties in gaining access to particular kinds of domain-specific information that are associated with aware expressions of knowledge in individual domains. Instances of first- and second-order accounts are illustrated with examples from studies of memory and amnesia. The relation between implicit knowledge and anosognosia is also discussed.

Prosopagnosia is clinically defined as a specific and extreme inability to recognize familiar faces. However, doubts have been expressed concerning prosopagnosics' preserved ability to recognize unfamiliar faces and to make other within category discriminations. The present study pursues these doubts. If recognition of unfamiliar faces and objects is intact, then prosopagnosics should demonstrate normal processing for all tasks that depend on the possession of intact stored visual descriptions at the category level. In particular, they should show normal face and object superiority effects. A detailed investigation was carried out on a well documented prosopagnosic (KD) and less extensively on three other (RB, AH and OA) well attested cases. Experiments 1 and 2 considered whether face and object superiority effects were observed in these patients. No difference in the pattern of recognition performance was found between normal and unusual arrangements of faces and objects. Their pattern of performance differed both from unilateral brain-damaged patients and normal controls. The results suggest both that these prosopagnosic patients were impaired on the recognition of unfamiliar faces and that their problem is not specific to faces. Experiment 3 showed that KD was impaired on a face/non-face decision task but appeared to benefit by the stimulus being presented in the normal orientation. For normal controls, mental rotation of a face appeared to be a separate process from face categorization. Experiment 4 found that KD, AH and OA were impaired, compared to normal controls, in their ability to recognize emotional expressions but not more than brain-damaged controls. The impairment of the prosopagnosics tested in the present study is placed at the interaction between stored object descriptions and the structural encoding stage of Bruce and Young. Consideration is given to an elaboration of the structural encoding stage in which boundary (category defining) information is separately processed from surface (detailed texture) information.

Three experiments investigating the patient M.S.'s semantic memory are reported. Experiments 1 and 2 involved a category-membership decision task, in which M.S. was asked to determine whether a noun was a member of a specified semantic category. His performance in Experiment 1 was impaired for nouns from living categories in comparison with nouns from nonliving categories, and this impairment was especially marked for nouns of low typicality. Experiment 2 demonstrated an equivalent pattern of very poor performance to nouns of low familiarity from living categories. In Experiment 3 the effect of a category label on lexical decision was examined, using category labels as primes preceding nouns or pronounceable nonwords. Facilitation from related category label primes was found for typical and untypical members of living and nonliving semantic categories. These findings demonstrate that M.S. has impaired knowledge of the structure of living semantic categories when explicit access to this information is required (Experiments 1 and 2), but that some form of preserved category structure can be demonstrated in tasks which assess this implicitly (Experiment 3).

Damage to different regions of the brain can cause a variety of neuropsychological deficits, including specific disturbances of language, memory, perception and motor function. A significant number of brain-damaged patients are unaware of their deficits, even when they are profound and have debilitating effects on patients' performance. This article reviews clinical observations and experimental investigations concerning unawareness of deficits, considers methodological issues, and critically evaluates different interpretations of the phenomenon. An integrative theoretical framework is proposed to account for unawareness of deficits in diverse neuropsychological syndromes. Possible directions for future research are outlined.

K.D. has been unable to recognize people's faces since sustaining cerebral injury in infancy. Investigation of this disorder carried out when K.D. was aged 8 to 11 years showed that although her basic visual abilities were impaired, they were no poorer than those of other children who recognized faces without difficulty. K.D. had learned to read, but had not regained ability to recognize people's faces; instead she relied primarily on voices as a cue to person recognition. There was no evidence of any degree of overt or covert recognition of familiar faces, and K.D. also experienced problems in visual object recognition. She could, however, classify a visual input as a face, was able to perceive and imitate facial expressions, and was able to perform face matching tasks to an extent limited by her use of a feature by feature matching strategy. It is suggested that K.D.'s impairment affected higher order perceptual abilities, and is in a number of respects comparable to the impairments found in adult prosopagnosic patients.

A patient with severe, lasting prosopagnosia could not get an immediate overview of a face sufficiently specific for successful identification. He also failed completely in tasks of visual closure despite adequate performances on numerous other tests of visual perception and memory. We conclude that prosopagnosia represents a loss of visual "configural processing"--a learned skill enabling immediate identification of individual members of a class without conscious visuospatial analysis or remembering. Prosopagnosia and agnosic alexia represent two distinct defects of configural processing: Alexics cannot identify items with distinctive features that are themselves identifiable. Prosopagnosics cannot identify objects whose critical distinguishing features have no independent identities.

Four patients with face agnosia, a condition in which there is a failure to recognize previously known faces or faces that ought to have been learned without difficulty, were studied with an experimental paradigm in which both overt (verbal self-report) and covert (electrodermal skin conductance response) probes of recognition were used. The results showed a striking dissociation between the two indices: (1) all 4 patients generated more frequent and significantly larger-amplitude skin conductance responses to familiar faces, as compared to unfamiliar ones. This outcome contrasts with the finding that (2) none of the patients was able to give discriminatory verbal ratings of familiar versus unfamiliar faces. The positive electrodermal discrimination is interpreted as an index of the rich co-activation of records that is produced when familiar facial stimuli successfully trigger the reassembly of previously acquired representations of the physical structure of faces. The results of this co-activation, however, are unavailable to consciousness. This is seen as the consequence of lesion-related disruption of linkages between face records, on the one hand, and non-face records that contain information uniquely and unequivocally apposite to the possessor of a particular face.

Investigations of the visual recognition abilities of the patient M.S. are reported. M.S. is unable to achieve overt recognition of any familiar faces, and many everyday objects. In Task 1 he showed semantic priming from name primes but not from face primes in a name recognition task. In Task 2 he showed no advantage in learning true (face + correct name) rather than untrue (face + someone else's name) pairings of faces and names. In Task 3 semantic priming of lexical decision was only found for object picture primes that M.S. was able to recognize overtly. In Task 4 faster matching of photographs of familiar than unfamiliar objects was only found for objects that M.S. was able to recognize overtly. These findings demonstrate an absence of covert recognition effects for M.S., consistent with the view that his impairment is primarily "perceptual" in nature.

We evaluated 46 patients with right hemisphere strokes for unilateral spatial neglect (USN), anosognosia, hemiasomatognosia, extinction, constructional disturbance, motor impersistence and organic mental syndrome. High correlations were found among the incidences of USN, anosognosia, hemiasomatognosia, extinction, motor impersistence and constructional disturbance. USN, hemiasomatognosia, motor impersistence, constructional disturbance and anosognosia tended to occur with large lesions. Organic personality syndrome was frequent (33%) and was more often associated with USN, anosognosia, hemiasomatognosia, extinction, constructional disturbance and motor impersistence than other psychiatric symptoms.

Neuropsychological testing of a patient with auditory agnosia showed that certain difficulties in the initial analysis of sounds may be the cause of his inability to understand spoken words and other sounds. Abnormalities included a slow reaction time to brief auditory stimuli (but not to equally brief visual stimuli or to longer auditory stimuli) and the need for approximately 1/4 sec of silence between two tones before the patient was able to hear them as separate. He could identify words and word associations if he was able to view the object whose name or word associate he was hearing. The findings imply that this patient's deficit in comprehending speech was probably apperceptive rather than associative in origin.

Studies of agnosia have revealed two apparently orthogonal dimensions along which knowledge may break down. In some cases, knowledge of specific categories (such as living things) seems lost, regardless of the modality being tested. In other cases, knowledge in specific modalities (such as vision) seems lost, regardless of the category of stimuli being tested. These different sets of phenomena suggest different organizations for knowledge in the brain, the first by category and the second by modality. Unfortunately, possible confoundings between category, modality, and difficulty level in the previous studies prevent us from drawing strong conclusions from these data. The present study was aimed at assessing the nature of the breakdown in the semantic memory of a prosopagnosic patient, by orthogonally varying category and modality, while assessing difficulty level. The findings do not implicate a simple categorical or modality-dependent organization of his knowledge, but rather an organization in which both category and modality play a role.