A bird is a bird is a bird: Making reference within and without superordinate categories

Adults with localized cerebral insult often err in their use of a word to refer to an object or an idea. It is important to assess, then, the patients' appreciation of what a word can refer to, and the way in which they may violate the borders around a referential field. Nonfluent aphasics, fluent aphasics, and nonaphasic patients with insult to the right hemisphere were asked to provide names of items which could be referred to by familiar superordinate terms like “bird.” The principal results revealed that the nonfluent aphasics are anchored to the central portions of a superordinate's referential field (naming items like “robin” and “sparrow,” for instance). While fluent aphasics often violate the borders around a referential field (e.g., providing “beaver” in response to “birds”), it was nevertheless possible to characterize some limits to their choice of a superordinate's referents. These findings were independent both of the absolute number of responses provided and the frequency of occurrence of the response. Further, the patients with insult to the left hemisphere produce few consecutive items whose referents hold attributes in common. When these clusters are produced by aphasics, they consist primarily of subordinates whose referents exhibit many overlapping features (e.g., “bald eagle, black eagle, golden eagle” in response to “bird”). The right-hemisphere-damaged subjects, in contrast, produce many clusters of related items. These consist of less central, basic object level words whose referents hold less obvious features in common (e.g., “albatross, crane, gull” in response to “bird”). Aphasics, then, may be limited in their ability to analyze referents for critical features. Taken together, these data contribute to a more precise characterization of the nonfluent aphasics' and the fluent aphasics' referential deficits, and lend support specifically to the notion that neither group of aphasics relies on definition-like features to determine what a word can refer to.     

The word order problem in agrammatism : I. Comprehension

The results of a picture-pointing comprehension test show that agrammatic aphasics have difficulty understanding sentences in which the underlying semantic roles are marked by the order of noun phrases around a verbal element. Agrammatic patients performed poorly on reversible constructions involving spatial prepositions (e.g., “The square is above the circle”) and verbs (e.g., “The dancer applauds the clown”). These results have significance for the interpretation of the underlying disturbance in agrammatism—whether the deficit is syntactic or purely phonological.     

The appreciation of antonymic contrasts in aphasia

To secure information on the ability of aphasic patients to comprehend antonymic relations, the kinds of confusions typically made, and the extent to which antonymic sensitivity depends upon mode of presentation and task demands, three linguistic and nonlinguistic tests were administered to aphasic patients, right hemisphere-damaged patients, and non-neurological controls. Although difficulty with antonymous relations was found among all the organic patients, the kinds of problems evidenced and the relative profile of difficulties differed across populations. Among the principal findings were the generally preserved sensitivity to antonymy found among anterior (particularly Broca's) aphasics; a surprising insensitivity to antonymy and a preference for synonyms, found among right hemisphere patients, particularly on the nonlinguistic tasks; a relative preservation of sensitivity to antonymy on nonlinguistic tasks, coupled with a loss of such sensitivity on linguistic tasks, found among posterior (particularly Wernicke's) aphasics; a proclivity toward stereotypical correct responses among the organic patients; and an absolutely worse performance by right hemisphere patients on tasks involving antonymic relations in pictures and abstract designs.     

Selective word-learning deficits in aphasia

The purpose of this study was to determine whether patients with focal brain damage can learn anything about a new word, and if so, whether selected aspects of the new word are acquired depending on the nature of the patient's language processing deficit. In the context of drawing pictures with a number of felt pens identical in all respects except color, agrammatic Broca's aphasics and fluent aphasics were exposed to the new word "bice," an adjective referring to the dark green portion of the color spectrum. Our findings revealed that brain-damaged patients can engage in lexical acquisition, but Broca's aphasics and fluent aphasics apparently learn about different aspects of the new word. Specifically, on successive exposures to "bice," both Broca's aphasics and fluent aphasics exhibit progressively more accurate hypotheses for identifying a bice-colored object. During subsequent assessments, agrammatic aphasics reveal on a metalinguistic judgment task their significant difficulty appreciating the grammatical form class of "bice"; on an object classification task, fluent aphasics are significantly impaired in their classification of bice-colored objects as "bice." Taken together, these unique word-learning profiles reinforce earlier observation on the selective nature of language processing deficits after focal left-hemisphere insult, and support the claim that separate language processing devices may be selectively compromised in different groups of aphasics. The relationship between syntactic and lexical semantic processing is discussed.     

Writing induces a right hemisphere linguistic advantage in dysphonetic dyslexic children: implications for attention and capacity models of laterality

An experiment demonstrated a complete hemispheric processing reversal in 10 male, dysphonetic dyslexic children that occurred during a dichotic listening test of their verbal working memory. Requiring a written response to dichotic digits produced a right hemisphere/left ear superiority in the dysphonetic dyslexics whereas normal subjects and other dyslexics maintained a left hemisphere/right ear advantage. This reversal was unaffected by changes in task difficulty. A second experiment assessed the influence on producing the reversal of concurrent manual interference with left hemisphere verbal processing (responding orally vs. manually) and selective right hemisphere priming (Forward Writing vs. Backward Writing). The dysphonetic children reverted to a strong left hemisphere superiority when recalling the dichotic digits orally. Backward writing produced no ear advantage in either direction. The findings suggest that dysphonetic dyslexia may be related to (1) left hemisphere processing demands that exceed capacity, (2) easily activated right hemisphere processing strategies and (3) failure to coordinate linguistic processing interhemispherically. The results supported a novel hybrid conceptualization of dyslexia consisting of a synthesis of selective activation, and dual processor-limited capacity, theories.     

Some aspects of language comprehension in anterior aphasia

The competency of language comprehension was evaluated in three groups: anterior aphasics, posterior aphasics, and normal control subjects. Test material was divided into two sentence groups (Fill in the Blank and True/False) emphasizing either (1) semantic, “real world,” identity words or (2) syntactic, relational words, and one paragraph interpretation task. Matching auditory and visual (written) presentations were given. The control subjects performed almost flawlessly but many errors were made by each aphasia group. Qualitative study revealed a marked difference in the comprehension problem of the two groups. The anterior aphasic group performed well on semantically weighted sentences but made errors on syntactically weighted material, regardless of mode of presentation. In contrast, the posterior aphasics made almost the same number of errors on both types of material, regardless of mode of presentation. These findings support the concept of defective language comprehension in anterior aphasia and further suggest that the defect centers on the syntactical structures which are also poorly handled in expressive output.     

Profiles of symbol-reading skills in organic patients

One (unitary) school of thought views all symbolic competences as closely related, while a rival (pluralistic) approach underscores the relative differences among modes of symbolic processing. To secure information on the plausibility of these competing hypotheses, matched groups of left- and right-hemisphere patients were given a visual symbol-recognition test. Subjects were required to choose the correctly depicted symbol among a set of four. The results challenge a strong version of the “unitary” hypothesis. What emerges instead is a view of symbol systems as a continuum: relatively linguistic symbol systems prove challenging for left-hemisphere patients, relatively nonlinguistic systems pose comparable difficulties for right-hemisphere patients. Contrary to hypothesis, the processing of numerical symbols poses special difficulty for right-hemisphere patients. Performance on trademarks—items which can be processed by linguistic or nonlinguistic strategies—suggests that organic patients with contrasting pathologies may adopt different processing strategies when confronting identical physical stimuli.     

Drawing deficits in brain-damaged patients' freehand pictures

This study examines errors in brain-damaged patients' attempts to produce freehand drawings of common objects in response to a linguistic target (e.g., "fruit"). The pictures were carefully analyzed according to the features which dictionaries claim should vary necessarily from item to item, including color, shape, relative size, and special features which help distinguish between similar items. A "recognizability score" was created to quantify patients' overall drawing capacity. The findings revealed that subjects with right hemispheric insult are significantly more impaired overall than left hemisphere-damaged patients in producing freehand pictures. However, freehand drawing skills do not break down in an undifferentiated fashion after right hemispheric insult: Group and individual data reveal that patients with right central (primarily parietal) insult are most impaired at expressing shape attributes in their pictures, right posterior patients with primarily temporoparietal insult experience the greatest difficulty attributing color to their pictures, but patients with right anterior insult are impaired at expressing color, shape, and relative size in their pictures. All patients with right hemisphere insult often attribute specific features indiscriminantly to any member of the same category, resulting in anomalous pictures like a "potato bush." One patient with left posterior insult seemed to encounter difficulty generating the mental images necessary to serve as the basis for his pictures. These findings are discussed with reference to an image-based model for freehand drawing.     

A study of alpha hemispheric asymmetries for verbal and nonverbal stimuli in males and females

The alpha hemispheric asymmetries of males and females were examined with electroencephalographic (EEG) techniques during exposure to connected speech and nonlinguistic stimuli. The subject selection controlled for familial handedness and each subject was administered the Block Design and Vocabulary Subtests of the WAIS as a general measure of “visual-spatial” and “verbal” ability. The results showed that there was less alpha in the right hemisphere for nonverbal tasks and less alpha in the left hemisphere for verbal tasks. The females showed significantly more “lateralization” during the tasks as compared to the males. The results are discussed in terms of processing differences and the possible effects of subject variables, stimulus mode, stimulus presentation, and task requirements on neurolinguistic research results.     

The relation between gesture and language in aphasic communication

Effective communication in aphasia depends not only on use of preserved linguistic capacities but also (and perhaps primarily) on the capacity to exploit alternative modalities of communication, such as gesture. To ascertain the capacity of aphasic patients to use gesture in their spontaneous communication, informally structured interviews were conducted with two Wernicke's aphasics and two Broca's aphasics, as well as with four normal controls. The performances of the patient groups were compared on the physical parameters of gesture, the points in the communication where gestures occurred, and several facets of the semantics and pragmatics of gesture. Generally speaking, the gestures of the aphasics closely paralleled their speech output: on most indices, the performance of the Wernicke's aphasics more closely resembled that of the normal controls. Wernicke's aphasics differed from normals in the clarity of their language and gestures: While individual linguistic units were often clear, the relation among units was not. In contrast, the Broca's aphasics equaled or surpassed the normal controls in the clarity of their communications. The results offer little support for the view that aphasic patients spontaneously enhance their communicative efficacy through the use of gesture; these findings can, however, be interpreted as evidence in favor of a “central organizer” which controls critical features of communication, irrespective of the modality of expression.     

A study of spelling in aphasia

To secure systematic information on spelling abilities following damage to the dominant hemisphere, a test probing performance in three modalities of response was administered to a group of aphasic patients. Except for a predictable deficit among anterior aphasics in oral spelling, anterior and posterior aphasics exhibited comparable performances on the measures of spelling. However, anterior and posterior aphasics differed from one another on the kinds of words they most accurately spelled, the errors they were prone to make, and certain strategies which they characteristically adopted. These results suggest two alternative approaches to spelling: one approach, common in posterior aphasics, entails choosing letter combinations on the basis of their customary sounds; a second approach, common among anterior aphasics, appears to rely on a partially preserved image of the word's appearance.     

Language in right-handers with right-hemisphere lesions: A preliminary study including anatomical, genetic, and social factors

A comprehensive test battery was devised to study the effects of right hemisphere lesions on the speech and language of “nonaphasic” dextrals. Data were thus obtained for 62 subjects, 20 of them neurologically healthy and 42 with a focal right hemisphere lesion resulting from a cerebro-vascular accident. A preliminary global analysis of these data is reported. Anomalies were observed in 33 brain-damaged subjects. Although discreet in all cases, these anomalies were shown to have various degrees of severity. Given the population submitted to this study, the subject most likely to show such anomalies was defined, genetically, as a right-handed adult with a family history of ambidextrality or left-handedness and, socially, as one with a relatively limited education. The implications of these findings are discussed together with the problem of the anatomo-clinical correlations of language disorders resulting from right hemisphere lesions in “nonaphasic” dextrals.     

The effect of voice and place among aphasic, nonaphasic right-damaged, and normal subjects on a metalinguistic task

Aphasic, nonaphasic right-damaged, and normal subjects sorted triads of stop consonants into pairs adjudged most similar. All groups sorted on the basis of linguistic features, but differed in their use of place versus voice: Normal and right-damaged subjects used place and voice equally often; aphasics relied significantly more upon voice than upon place. These results are interpreted to reflect an alteration at the level of linguistic representation in aphasics and not simply a perceptual difficulty. It is suggested that this altered representation stems from aphasics' extended use of normal linguistic capacities of the right hemisphere.     

The effect of an intensive behavioral program on the distribution of EEG alpha power in stutterers during the processing of verbal and visuospatial information

Prior to an intensive behavioral treatment program, stutterers showed greater than normal activation of the posterior frontal region of the right hemisphere during the performance of speech tasks. After treatment they showed increases in proportional alpha for most regions of the two cerebral hemispheres, but most markedly for the posterior frontal region of the right hemisphere for both verbal and nonverbal tasks. This increase resulted in a reversal of the previous R/L interhemispheric alpha relationships with the left posterior frontal region showing greater activation during speech after treatment. The relationship of this finding to previous findings is briefly discussed and an hypothesis of decreased inhibitory control of the right hemisphere at the posterior frontal region by the left hemisphere during speech in stutterers is proposed and briefly expounded.     

The brain is not single-minded about inflectional morphology: A response to the commentaries

Jaeger is supportive of our experiment and the claims we make, arguing that the weight of current evidence shows the brain making a distinction between regular and irregular inflectional morphology. Seidenberg & Arnoldussen are unsupportive, criticizing our work on theoretical and methodological grounds. Seidenberg & Arnoldussen’s major worries—that we have misunderstood connectionist theory’s predictions and have committed a “Difficulty Matching Error” in testing them—are important to consider but turn out to be groundless. At bottom, Seidenberg & Arnoldussen fail to recognize the consequences of our choice of German words, rather than English, as stimuli. Once the concept of “difficulty” is given substance in this context, it appears that in German, the brain activates more extensively when dealing with what in the connectionist universe should be, if anything, the easier stimuli, not the harder ones as suggested by Seidenberg & Arnoldussen. Thus regularity cannot be reduced to difficulty.     

Linking together different measures of preference: A dynamic model of matching derived from decision field theory

Two frequently used tasks for measuring preferences among gambles are choice and selling price tasks. However, the rank orders observed with these tasks do not agree, and these disagreements are called preference reversals. In this article, we propose an extension of decision field theory that was originally designed to account for choice probability and the distribution of choice response times. In this extension, we show how this same theory can be used to derive predictions for the distribution of values produced by selling price tasks. This model not only accounts for the basic preference reversal results but also can explain the effects of various information processing factors on preference reversals including time, effort, and practice. We conclude by summarizing the advantages of the decision field matching model over two earlier models of choice and selling prices—expression theory and the contingent weighting model.     

Part of speech and phonological form implied in written-word comprehension: Evidence from homograph disambiguation by normal and aphasic subjects

A sentence construction experiment examining the effect of part of speech and phonological form in written-word comprehension is reported. Normal and aphasic subjects had to write sentences incorporating a given word pair, one word was a homograph (e.g., “bank”) whose meaning was context-biased by the other (e.g., “money”/“river”). The effect of three psycholinguistic factors on subjects' performance was questioned: (i) The relative frequency of one meaning of the homograph as compared to the other meaning; (ii) The lexical/syntactic ambiguity (“ball”/“can”); (iii) The same/different phonological forms of the two meanings (“fair”/“bass”). The results are discussed in the framework of a model in which multiple special-purpose procedures are involved in normal processing, some of them being differentially impaired by brain disease in Broca's and Wernicke's aphasics.     

Crossed aphasia in an illiterate dextral

An 83 year old illiterate, right-handed woman developed a persistent nonfluent aphasia following a right cerebral infarction (crossed aphasia). Computerized axial tomography localized the lesion to the right posterior frontal lobe.It is suggested that the neural mechanisms involved in learning to read and write may be critical for the complete establishment and maintenance of language dominance in the left hemisphere, and that, in this case, the patient's failure to acquire reading and writing skills altered the normal evolution of language lateralization and resulted in the right hemisphere assuming the dominant role.     

Reversal learning by fornix-transected monkeys

Experiment 1 examined visual reversal learning and in Experiment 2 monkeys were trained to criterion in a serial reversal set between “FR” and “DRO” response requirements. In both cases impairments were observed in fornix-transected monkeys. These results are discussed in connection with previous findings that in serial reversals damage to the hippocampal system in monkeys causes a deficit in spatial but not in visual learning. A unified account is proposed.     

Memory and encoding of spoken discourse following right hemisphere damage: evidence from the Auditory Moving Window (AMW) technique

We investigated the hypotheses that impaired discourse processing following right hemisphere damage is mediated by task difficulty and is associated with deficits in discourse encoding. Spoken discourse passages differing in contextual predictability were presented to right hemisphere-damaged (RHD) patients and to non-brain-damaged (NBD) controls for subsequent recall using the Auditory Moving Window paradigm. To manipulate processing difficulty, speech segments were of normal or accelerated speech rates. The recall results showed that RHD adults recalled less than NBD controls overall and failed to recall major idea units better than minor idea units for high predictability passages presented at accelerated speech rates. Both RHD patients and NBD controls failed to recall major idea units better than minor idea units for low predictability passages, regardless of speech rate. The encoding results showed that RHD adults were both slower overall and differentially slower than NBD controls when listening to accelerated passage segments. Taken together, the encoding and recall results are consistent with the view that extracting passage gist under difficult listening conditions is especially vulnerable for patients with right hemisphere strokes.