Nouns,verbs, objects,actions, and the animate/inanimate effect

We report an aphasic patient, Z.B.L., who showed a significant advantage for verbs compared to nouns in picture-naming tests. Within the object class, he performed better on animate things than on nonliving things in picture naming as well as in an “attribute judgement task”. This pattern of performance is contrary to the central prediction of a recent proposal (Bird, Howard, & Franklin, 2000 Bird, H., Howard, D. and Franklin, S. 2000. Why is a verb like an inanimate object? Grammatical category and semantic category deficits. Brain and Language, 72: 246–309. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), which attributes noun–verb dissociation in aphasic patients to deficits in processing certain kinds of semantic features. This model proposes that conceptual representations of verbs have a lower proportion of sensory features than do representations of nouns; the same is proposed for inanimate versus animate items within the noun category. Noun deficits are assumed to arise due to impairment for the processing of sensory features. The model predicts that if a patient is more impaired for nouns than for verbs, he will also display more difficulty with animate than with inanimate objects. Contrary to predications derived from this theory, Z.B.L. performed better with animate than inanimate nouns.     

The noun/verb dissociation in language production: varieties of causes

We report the performance of two patients who presented with complementary deficits in naming nouns relative to verbs: EA performed far worse with nouns than verbs, while MR performed worse with verbs than nouns. The two patients' grammatical category-specific deficits could not easily be explained in terms of damage to specific types of semantic knowledge prototypically associated with nouns (visual properties) and verbs (action features). One of the two patients, MR, also presented with a selective deficit in processing verbal as opposed to nominal morphology, in line with her impairment in naming verbs. The other patient, EA, showed no impairment in producing nominal and regular verbal morphology. The contrasting patterns of grammatical category-specific deficits in naming and morphological processing, along with other recently reported patterns, are interpreted as providing support for the claim that semantic and grammatical properties independently contribute to the organisation of lexical processes in the brain.     

Grammatical class in lexical production and morhpological processing: Evidence from a case of fluent aphasia

We present the case of a fluent aphasic patient who is impaired at producing nouns relative to verbs in picture naming, sentence completion, and sentence generation tasks, but is better at both producing and comprehending concrete nouns than abstract nouns. Moreover, he displays a selective difficulty in producing the plural forms of some nouns and pseudowords presented as nouns, but was able to produce the phonologically identical third-person singular forms of corresponding verb homonyms and of the same pseudowords presented as verbs. This pattern of performance casts doubt on the hypothesis that grammatical class effects are always epiphenomena of more general semantic impairments that affect the naming of actions or of concrete objects, and suggests that these effects may arise instead from damage to syntactic processes pertaining specifically to the grammatical properties of words. We also discuss the implications of such damage for models of morphological processing.     

Grammatical class in lexical production and morhpological processing: Evidence from a case of fluent aphasia

We present the case of a fluent aphasic patient who is impaired at producing nouns relative to verbs in picture naming, sentence completion, and sentence generation tasks, but is better at both producing and comprehending concrete nouns than abstract nouns. Moreover, he displays a selective difficulty in producing the plural forms of some nouns and pseudowords presented as nouns, but was able to produce the phonologically identical third-person singular forms of corresponding verb homonyms and of the same pseudowords presented as verbs. This pattern of performance casts doubt on the hypothesis that grammatical class effects are always epiphenomena of more general semantic impairments that affect the naming of actions or of concrete objects, and suggests that these effects may arise instead from damage to syntactic processes pertaining specifically to the grammatical properties of words. We also discuss the implications of such damage for models of morphological processing.     

THE NOUN/VERB DISSOCIATION IN LANGUAGE PRODUCTION: VARIETIES OF CAUSES

Abstract

We report the performance of two patients who presented with complementary deficits in naming nouns relative to verbs: EA performed far worse with nouns than verbs, while MR performed worse with verbs than nouns. The two patients' grammatical category-specific deficits could not easily be explained in terms of damage to specific types of semantic knowledge prototypically associated with nouns (visual properties) and verbs (action features). One of the two patients, MR, also presented with a selective deficit in processing verbal as opposed to nominal morphology, in line with her impairment in naming verbs. The other patient, EA, showed no impairment in producing nominal and regular verbal morphology. The contrasting patterns of grammatical category-specific deficits in naming and morphological processing, along with other recently reported patterns, are interpreted as providing support for the claim that semantic and grammatical properties independently contribute to the organisation of lexical processes in the brain.     

Morphological processing of polymorphemic nouns in a highly inflecting language

Abstract

We explored the processing of morphologically complex nouns in an aphasic who is a native speaker of Finnish, a language with rich morphology. This patient made numerous morphological errors with inflected nouns in oral reading, repetition, and word elicitation. In contrast, reading and repetition of both base form and derived nouns was significantly better. The cross-modal nature of his morphological difficulties together with other experimental evidence for a semantic impairment indicated that a central deficit played a significant role in his problems with inflected nouns. This suggests a difference in the processing of inflectional vs. derivational morphology at the semantic level. In addition, the patient occasionally produced illegal stem + affix combinations. As these errors appeared in the absence of phonological paraphasias, they support the view that the phonological output lexicon has a morpheme-based organisation in Finnish. Finally, it was hypothesised that the stem representations of inflected nouns in the phonological output lexicon may be allomorph-based because formal transparency of inflection did not affect oral reading or word elicitation performance.     

Modeling the meaning of words: neural correlates of abstract and concrete noun processing

We present a model relating analysis of abstract and concrete word meaning in terms of semantic features and contextual frames within a general framework of neurocognitive information processing. The approach taken here assumes concrete noun meanings to be intimately related to sensory feature constellations. These features are processed by posterior sensory regions of the brain, e.g. the occipital lobe, which handles visual information. The interpretation of abstract nouns, however, is likely to be more dependent on semantic frames and linguistic context. A greater involvement of more anteriorly located, perisylvian brain areas has previously been found for the processing of abstract words. In the present study, a word association test was carried out in order to compare semantic processing in healthy subjects (n=12) with subjects with aphasia due to perisylvian lesions (n=3) and occipital lesions (n=1). The word associations were coded into different categories depending on their semantic content. A double dissociation was found, where, compared to the controls, the perisylvian aphasic subjects had problems associating to abstract nouns and produced fewer semantic framebased associations, whereas the occipital aphasic subject showed disturbances in concrete noun processing and made fewer semantic feature based associations.     

A tale of two agnosias: distinctions between form and integrative agnosia

The performance of two patients with visual agnosia was compared across a number of tests examining visual processing. The patients were distinguished by having dorsal and medial ventral extrastriate lesions. While inanimate objects were disadvantaged for the patient with a dorsal extrastriate lesion, animate items are disadvantaged for the patient with the medial ventral extrastriate lesion. The patients also showed contrasting patterns of performance on the Navon Test: The patient with a dorsal extrastriate lesion demonstrated a local bias while the patient with a medial ventral extrastriate lesion had a global bias. We propose that the dorsal and medial ventral visual pathways may be characterized at an extrastriate level by differences in local relative to more global visual processing and that this can link to visually based category-specific deficits in processing.     

A tale of two agnosias: Distinctions between form and integrative agnosia

The performance of two patients with visual agnosia was compared across a number of tests examining visual processing. The patients were distinguished by having dorsal and medial ventral extrastriate lesions. While inanimate objects were disadvantaged for the patient with a dorsal extrastriate lesion, animate items are disadvantaged for the patient with the medial ventral extrastriate lesion. The patients also showed contrasting patterns of performance on the Navon Test: The patient with a dorsal extrastriate lesion demonstrated a local bias while the patient with a medial ventral extrastriate lesion had a global bias. We propose that the dorsal and medial ventral visual pathways may be characterized at an extrastriate level by differences in local relative to more global visual processing and that this can link to visually based category-specific deficits in processing.     

Object identification in simultanagnosia: When wholes are not the sum of their parts

We examined object identification in two simultanagnosic patients, ES and GK. We show that the patients tended to identify animate objects more accurately than inanimate objects (Experiments 1 and 4). The patients also showed relatively good identification of objects that could be recognised from their global shape, but not objects whose recognition depended on their internal detail (Experiment 2). Indeed, the presence of local segmentation cues disrupted global identification (Experiment 3). Identification was aided, though, by the presence of surface colour and texture (Experiment 4). We suggest that the patients could derive global representations of objects that served to recognise animate items. In contrast, they were impaired at coding parts-based representations for the identification of inanimate objects.     

Object identification in simultanagnosia: When wholes are not the sum of their parts

Abstract

We examined object identification in two simultanagnosic patients, ES and GK. We show that the patients tended to identify animate objects more accurately than inanimate objects (Experiments 1 and 4). The patients also showed relatively good identification of objects that could be recognised from their global shape, but not objects whose recognition depended on their internal detail (Experiment 2). Indeed, the presence of local segmentation cues disrupted global identification (Experiment 3). Identification was aided, though, by the presence of surface colour and texture (Experiment 4). We suggest that the patients could derive global representations of objects that served to recognise animate items. In contrast, they were impaired at coding parts-based representations for the identification of inanimate objects.     

An influence of syntactic and semantic variables on word form retrieval

We report the case of DPI, an aphasic patient who shows a phonological impairment in production that spares certain syntactic and semantic categories. On a picture naming task, he produces mostly phono-logical paraphasias, and the probability of producing a correct response depends on the frequency and length of the target word. This deficit occurs in the presence of spared ability to find the grammatical gender of the items that he cannot name, intact conceptual knowledge, and very good reading and word repetition. Therefore, we conclude that DPI's deficit is restricted to the phonological retrieval of a correctly selected lexical entry. However, production errors are not uniform across semantic and syntactic domains. Numerals and names of days and months are totally spared compared to matched controls. In addition, abstract nouns and verbs are significantly less affected than concrete nouns, even when variables affecting phonological retrieval (frequency, length, syllabic structure) are controlled for. This suggests that a functional organisation in terms of semantic and syntactic variables exists at the level of phonological retrieval. We discuss these findings in light of current models of speech production.     

AN INFLUENCE OF SYNTACTIC AND SEMANTIC VARIABLES ON WORD FORM RETRIEVAL

We report the case of DPI, an aphasic patient who shows a phonological impairment in production that spares certain syntactic and semantic categories. On a picture naming task, he produces mostly phono-logical paraphasias, and the probability of producing a correct response depends on the frequency and length of the target word. This deficit occurs in the presence of spared ability to find the grammatical gender of the items that he cannot name, intact conceptual knowledge, and very good reading and word repetition. Therefore, we conclude that DPI's deficit is restricted to the phonological retrieval of a correctly selected lexical entry. However, production errors are not uniform across semantic and syntactic domains. Numerals and names of days and months are totally spared compared to matched controls. In addition, abstract nouns and verbs are significantly less affected than concrete nouns, even when variables affecting phonological retrieval (frequency, length, syllabic structure) are controlled for. This suggests that a functional organisation in terms of semantic and syntactic variables exists at the level of phonological retrieval. We discuss these findings in light of current models of speech production.     

Comprehension of reversible sentences in aphasia: the effects of verb meaning

Comprehension of semantically reversible active and passive voice sentences was tested in a timed sentence/picture verification task. Three sets of six verbs were identified that incorporated different features of meaning relevant to the assignment of nouns to the thematic role of agent. Normal control subjects showed an effect of verb set on their response times, with significant effects between sets in the predicted direction. A group of aphasic patients without sentence comprehension disorder also showed a significant effect of verb set despite long and variable response times. A group of patients with reversible comprehension disorder in screening tasks showed weaker effects, primarily because of the use of consistent response biases that ignored the sentence verb. An experimental treatment of active/passive comprehension was conducted with two of these latter patients; one patient reached ceiling in post-testing, and the other showed significant improvement but demonstrated residual comprehension problems that indicated differences across verb sets. Results support the critical importance of verb meaning to normal and aphasic sentence comprehension.     

An electrophysiological analysis of animacy effects in the processing of object relative sentences.

Event-related brain potentials (ERPs) were used to investigate how and when a semantic factor (animacy) affects the early analysis of a difficult syntactic structure, namely, object relative sentences. We contrasted electrophysiological and behavioral responses to two object relative types that were syntactically and lexically identical and varied only in the order of the component animate and inanimate nouns [Inanimate (Animate) vs. Animate (Inanimate)]. ERPs were recorded from 40 subjects to each word of 30 I(A) and 30 A(I) sentences that occurred randomly among a set of various other sentence types read for comprehension. ERP effects to the early noun animacy manipulation were observed beginning with the initial noun and extending past the main clause verbs. We interpret the timing and multitude of electrophysiological effects, including the N400, P600, and left-anterior negativity, as evidence that both semantic and syntactic, and perhaps other types of information, are used early during structural analysis and message-level computations as needed for comprehension.     

Treatment of thematic mapping in sentence comprehension: implications for normal processing

Abstract

The inability of some aphasic patients to interpret semantically reversible sentences has been hypothesised to arise from failure to link the grammatical roles of nouns (e.g. subject, object) to their corresponding thematic roles (e.g. agent, patient). Several previous attempts to improve patients' thematic mapping abilities have demonstrated a range of treatment effects of considerable relevance to the development of cognitive models of sentence processing. This study reports a new treatment approach to thematic mapping impairment; it succeeded in improving auditory sentence comprehension in a chronic aphasic patient with a long-standing comprehension deficit. Generalisation of improvement to auditory comprehension of sentences with untreated verbs, to comprehension of written sentences, and to tests using pictorial and videotaped materials not used in treatment, place constraints on the range of possible interpretations of the functional locus of treatment effects. Two areas that did not show significant improvement following treatment included auditory comprehension of sentences lengthened with modifiers, and spoken production of active and passive sentences that express correct thematic roles. These null effects are also interpreted as providing information relevant to models of sentence processing, including the role of working memory in sentence comprehension and the nature of thematic mapping procedures in comprehension and production.     

Consequences of an inhibition deficit for word production and comprehension: Evidence from the semantic blocking paradigm

We investigated the semantic blocking effect in picture naming and word–picture matching for two nonfluent aphasic patients who show evidence of a deficit in inhibiting verbal representations (M.L. and B.Q.), one fluent aphasic patient (K.V.), and neurologically intact control participants. In two picture-naming tasks (Experiments 1A and 1B), M.L. and B.Q., relative to controls, showed a greatly exaggerated semantic blocking effect in naming latencies that increased dramatically across repeated presentations. On two corresponding word–picture matching tasks (Experiments 2A and 2B), both also showed an increasing semantic blocking effect, though the effects were not as large nor as consistent as those in naming. The fluent patient, K.V., showed a pattern like controls on both tasks. On an associated word–picture matching task, both M.L. and B.Q. showed results paralleling those of controls. The contrast between the production and comprehension patterns for M.L. and B.Q. supports the conclusion that their exaggerated blocking effect in production arises during lexical rather than semantic selection. We postulate that M.L.'s (and potentially B.Q.'s) production effect is due to difficulties in postselection inhibition, which results in overactivation of lexical representations. This overactivation is likely to be one source of their nonfluency in spontaneous speech.     

Comprehension of reversible sentences in aphasia: the effects of verb meaning

Abstract

Comprehension of semantically reversible active and passive voice sentences was tested in a timed sentence/picture verification task. Three sets of six verbs were identified that incorporated different features of meaning relevant to the assignment of nouns to the thematic role of agent. Normal control subjects showed an effect of verb set on their response times, with significant effects between sets in the predicted direction. A group of aphasic patients without sentence comprehension disorder also showed a significant effect of verb set despite long and variable response times. A group of patients with reversible comprehension disorder in screening tasks showed weaker effects, primarily because of the use of consistent response biases that ignored the sentence verb. An experimental treatment of active/passive comprehension was conducted with two of these latter patients; one patient reached ceiling in post-testing, and the other showed significant improvement but demonstrated residual comprehension problems that indicated differences across verb sets. Results support the critical importance of verb meaning to normal and aphasic sentence comprehension.     

Differences between nouns and verbs after anterior temporal lobectomy

To test the claim that lesions of left anterior and middle temporal cortical structures specifically impair processing of nouns but not verbs, 56 left-hemisphere-language-dominant patients who had undergone anterior temporal lobectomy (ATL) completed tasks assessing confrontation naming of pictured objects and actions, generation of synonyms for nouns and verbs, and semantic lexical judgments about nouns and verbs. Compared with right ATL patients, left ATL patients were impaired across different tasks that assessed naming and comprehension of high-imageability as well as low-imageability nouns. These groups did not differ, however, in verb naming or comprehension on most tasks. Results are consistent with the hypothesized specialization of left temporal lobe structures for processing nouns and suggest that naming problems commonly seen after left ATL extend beyond difficulties with retrieving object names and may be related to subtle disturbances in comprehension of the meanings underlying nominal word forms.     

Density pervades: an analysis of phonological neighbourhood density effects in aphasic speakers with different types of naming impairment

We investigated the influence of phonological neighbourhood density (PND) on the performance of aphasic speakers whose naming impairments differentially implicate phonological or semantic stages of lexical access. A word comes from a dense phonological neighbourhood if many words sound like it. Limited evidence suggests that higher density facilitates naming in aphasic speakers, as it does in healthy speakers. Using well-controlled stimuli, Experiment 1 confirmed the influence of PND on accuracy and phonological error rates in two aphasic speakers with phonological processing deficits. In Experiments 2 and 3, we extended the investigation to an aphasic speaker who is prone to semantic errors, indicating a semantic deficit and/or a deficit in the mapping from semantics to words. This individual had higher accuracy, and fewer semantic errors, in naming targets from high- than from low-density neighbourhoods. It is argued that the Results provide strong support for interactive approaches to lexical access, where reverberatory feedback between word- and phoneme-level lexical representations not only facilitates phonological level processes but also privileges the selection of a target word over its semantic competitors.