On the processing of regular and irregular forms of verbs and nouns: evidence from neuropsychology

Following acquired brain damage, a native English speaking patient (AW) encountered problems accessing phonology in speech production, while her ability to access word meaning appeared to be intact. In a series of tasks, AW was presented either with a verb, and was asked to produce its past tense or past participle (walk --> "walked"), or with a noun, and was asked to produce its plural (glove --> "gloves"). A stark dissociation was found: while AW responded accurately with regular forms of verbs (walked) and nouns (gloves), performance was significantly less accurate with irregular forms (found; children). The appearance of a selective deficit for irregular forms in conditions of impaired lexical access is in line with dual-mechanism accounts, which proposes that irregular forms are specified in the lexicon whereas regular forms are computed via rule-based mechanisms. In contrast, AW's data are problematic for connectionist accounts that do not posit separate mechanisms for processing regular and irregular forms, including the connectionist model recently proposed by Joanisse and Seidenberg (Proceedings of the National Academy of Sciences USA 96 (1999) 7592) which successfully simulated a variety of earlier neuropsychological findings. Analyses of AW's responses shed light on further details of the representation and processing of regular and irregular inflected forms.     

The processing of verbs and nouns in neural networks: insights from synthetic brain imaging

The paper presents a computational model of language in which linguistic abilities evolve in organisms that interact with an environment. Each individual's behavior is controlled by a neural network and we study the consequences in the network's internal functional organization of learning to process different classes of words. Agents are selected for reproduction according to their ability to manipulate objects and to understand nouns (objects' names) and verbs (manipulation tasks). The weights of the agents' neural networks are evolved using a genetic algorithm. Synthetic brain imaging techniques are then used to examine the functional organization of the neural networks. Results show that nouns produce more integrated neural activity in the sensory-processing hidden layer, while verbs produce more integrated synaptic activity in the layer where sensory information is integrated with proprioceptive input. Such findings are qualitatively compared with human brain imaging data that indicate that nouns activate more the posterior areas of the brain related to sensory and associative processing, while verbs activate more the anterior motor areas.     

Regularity revisited: evidence from lexical access of verbs and nouns in Greek

The present study investigates the relationship between morphological regularity and form during lexical processing using a visual priming paradigm varying the prime duration. We addressed the effect of regularity on morphological facilitation in nouns and verbs by exploiting particular characteristics of a highly inflected language, Greek, in which it is possible to manipulate morphological regularity while controlling the degree of orthographic overlap between morphological relatives. The effects of morphological regularity were found to crucially depend on the time course of lexical access. Moreover, morphological regularity was found to affect nouns and verbs differentially. We interpret these findings with respect to the distinction between affix processing and allomorph retrieval and discuss the issues of form overlap and orthographic boundaries in morphological processing.     

Pair-relational encoding of performed nouns and verbs

Summary Subjects had to learn lists of noun pairs and verb pairs. They were informed in advance about the test types and were tested for free recall (FR) and cued recall (CR). Three classes of encoding instructions were used: standard learning instructions, item-specific enactment instructions (to perform the denoted action of the verb or a typical action for the noun, and to do the same plus finding separate goals for the two elements of each pair), and enactment instructions that were completed by explicit instructions to integrate the word pairs (find a common goal, and find a common goal plus rating your success). There was no effect of encoding instructions on FR of nouns. There was a better FR under all enactment instructions than under standard instructions for verbs. CR decreased after item-specific enactment instructions, in contrast with standard learning instructions, but more for nouns than for verbs. CR increased after the instructions to integrate the pairs, in contrast with item-specific enactment instructions, but more for nouns than for verbs. It was concluded that enactment provides excellent item-specific information that can hardly be enhanced further, and that the item-specific information provided by concrete nouns is fundamentally good and is difficult to enhance by enactment. It is further assumed that enactment not only provides excellent item-specific information, but also hinders pair integration. Therefore, CR decreases after enactment. This decrease can only be overcome when subjects actively try to integrate the word pairs.     

Lexical representations of written nouns and verbs in Italian

This study investigates the differences in the input representations of verbs and nouns in the Italian mental lexicon. One visual lexical decision experiment in which the stem homograph effect (Laudanna, Badecker, and Caramazza, 1989) was evaluated on noun and verb targets is reported. Strong inhibitory effects on verb targets preceded by stem homographs relative to nonhomographic word pairs were found. The effects on verb targets were also much more reliable than the effects on noun targets. The pattern of results provides support for the hypothesis that noun and verbs are differently represented in the orthographic input lexicon.     

A motor isolation effect: When object manipulability modulates recall performance

Previous studies suggested that the language production architecture is recruited during verbal retention, and others proposed that spatial memory relies on the oculomotor system. The objective of the present study was to investigate the role of the motor system in object memory, by examining the effect of objects' affordances on retention. In a serial recall task, we manipulated the manipulability of objects to retain in memory. We used an isolation paradigm where we isolated the manipulability level of one object from the list. We showed that recall performance improved for the isolated object (Experiment 1) and that this advantage was abolished when participants were required to perform motor suppression during the task (Experiment 2). In Experiment 3, we showed that the abolition of the motor isolation effect in Experiment 2 was not due to an effect of distraction since motor suppression was shown not to interfere with a semantic isolation effect. It is argued that motor affordances play a role in object memory, but only when the motor characteristics of an object allow discriminating it from the other objects in the list.     

Infants use known verbs to learn novel nouns: Evidence from 15- and 19-month-olds

Fluent speakers’ representations of verbs include semantic knowledge about the nouns that can serve as their arguments. These “selectional restrictions” of a verb can in principle be recruited to learn the meaning of a novel noun. For example, the sentence He ate the carambola licenses the inference that carambola refers to something edible. We ask whether 15- and 19-month-old infants can recruit their nascent verb lexicon to identify the referents of novel nouns that appear as the verbs’ subjects. We compared infants’ interpretation of a novel noun (e.g., the dax) in two conditions: one in which dax is presented as the subject of animate-selecting construction (e.g., The dax is crying), and the other in which dax is the subject of an animacy-neutral construction (e.g., The dax is right here). Results indicate that by 19 months, infants use their representations of known verbs to inform the meaning of a novel noun that appears as its argument.     

The influence of age of acquisition,root frequency,and context availability in processing nouns and verbs

In the Italian language there is a higher number of inflectional suffixes in verbs than in nouns, and this might imply that verbs are more likely to undergo a morphological analysis in terms of root and suffix as compared to nouns (Traficante & Burani, unpublished observations). Moreover, verbs tend to be more abstract than nouns, and this aspect might make verb processing more difficult. Finally, the developmental gap in the production of nouns and verbs suggests that age of acquisition might affect noun and verbs differently. Nouns and verbs were presented in a lexical decision and in a naming task. The morphological variable root frequency in addition to word frequency, length and word age of acquisition, and the semantic variables concreteness and context availability (Schwanenflugel, Harnishfeger, & Stowe, 1988) were used as predictors in multiple-regression analyses in which lexical decision and naming latencies were the dependent variables. The results showed that age of acquisition, context availability, and root frequency are all important in predicting both lexical decision and naming latencies for nouns and verbs, but age of acquisition and root frequency are better predictors of the differences in processing Italian nouns and verbs.     

Broca's aphasia, verbs and the mental lexicon

Verb production is notoriously difficult for individuals with Broca's aphasia, both at the word and at the sentence level. An intriguing question is at which level in the speech production these problems arise. The aim of the present study is to identify the functional locus of the impairment that results in verb production deficits in Broca's aphasia. Levelt's (1989) model is used as a theoretical framework for this study. Two experiments have been conducted, one on verb movement and one on verbs with alternating transitivity. The results suggest that the functional impairment in Broca's aphasia should be located in Levelt's "grammatical encoder."     

Proper and common nouns: form class judgments in Broca's aphasia

Studies of agrammatic Broca's aphasics' comprehension of sentences containing articles have demonstrated profound deficits. It has not been clear whether the impairments are due to an inability to isolate the article in the stream of speech, or to difficulty in the construction and/or interpretation of various syntactic, semantic, or pragmatic levels of representation. This paper reports three experiments on Broca's aphasics' ability to distinguish between common nouns (e.g., "a rose") and proper nouns (e.g., "Rose"). This grammatical form class decision is signaled by the presence or absence of an article, and is represented at the lexical node level of linguistic analysis. The three experiments demonstrated that Broca's aphasics point to pictures representing classes of objects when asked to point to "the X" and point to pictures representing unique individuals when asked to point to "X". Thus, they were shown to be able to use the presence or absence of an article to determine lexical category. Their performance was especially accurate in an oral language context which was highly redundant and in a written language context where patients themselves could control the rate of information flow. They were quantitatively impaired, relative to controls, in a third study, which made higher information processing demands. Moreover, in this third study nonsense syllables preceding the noun which are phonologically similar to a known article were much more likely to evoke the misclassification of its noun as common than were phonologically distinct nonsense syllables. These data indicate that Broca's aphasics indeed have some difficulty isolating the article in the stream of speech. Nevertheless, detailed analyses of aphasics' performance revealed their ability to distinguish between common nouns and proper nouns even under these demanding conditions. Taken together, the three studies show that insofar as agrammatic patients are able to keep track of the presence or absence of articles, they can make a grammatical decision at the lexical node level of linguistic analysis. We conclude, then, that agrammatic Broca's aphasics are particularly impaired in the use of articles to construct and/or interpret phrasal constituents.     

Gulf Arabic nouns and verbs: A standardized set of 319 object pictures and 141 action pictures,with predictors of naming latencies

Standardized pictorial stimuli and predictors of successful picture naming are not readily available for Gulf Arabic. On the basis of data obtained from Qatari Arabic, a variety of Gulf Arabic, the present study provides norms for a set of 319 object pictures and a set of 141 action pictures. Norms were collected from healthy speakers, using a picture-naming paradigm and rating tasks. Norms for naming latencies, name agreement, visual complexity, image agreement, imageability, age of acquisition, and familiarity were established. Furthermore, the database includes other intrinsic factors, such as syllable length and phoneme length. It also includes orthographic frequency values (extracted from Aralex; Boudelaa & Marslen-Wilson, 2010). These factors were then examined for their impact on picture-naming latencies in object- and action-naming tasks. The analysis showed that the primary determinants of naming latencies in both nouns and verbs are (in descending order) image agreement, name agreement, familiarity, age of acquisition, and imageability. These results indicate no evidence that noun- and verb-naming processes in Gulf Arabic are influenced in different ways by these variables. This is the first database for Gulf Arabic, and therefore the norms collected from the present study will be of paramount importance for researchers and clinicians working with speakers of this variety of Arabic. Due to the similarity of the Arabic varieties spoken in the Gulf, these different varieties are grouped together under the label “Gulf Arabic” in the literature. The normative databases and the standardized pictures from this study can be downloaded from http://qufaculty.qu.edu.qa/tariq-khwaileh/download-center/.     

Neural correlates of comprehension and production of nouns and verbs in Chinese

This paper reports a conjunction analysis between semantic relatedness judgment and semantic associate generation of Chinese nouns and verbs with concrete or abstract meanings. The results revealed a verb-specific task-independent region in LpSTG&MTG, and task-dependent activation in a left frontal region in semantic judgment and the left SMG in semantic associate production. The observation of word class effects converged on Yu, Law, Han, Zhu, and Bi (2011), but contrasted with null findings in previous reports using a lexical decision task. While word class effects in the left posterior temporal cortices have been described in previous studies of languages with rich inflectional morphology, the significance of this study lies in its demonstration of the effects in these regions in a language known to have little inflectional morphology. In other words, differential neural responses to nouns and verbs can be observed without confounding from morphosyntactic operations or contrasts between actions and objects.     

The effect of context on the processing of type-shifting verbs

Recent research in lexical semantics has suggested that verbs such as begin and enjoy semantically select for a complement that denotes an activity or an event. When no such activity or event is specified in the form of a progressive or infinitival complement, as in John began (to read/reading) the book, the verb is said to "coerce" the NP direct object to shift its role to encompass the activity that begin requires as complement (e.g., writing, reading). Empirical support for this view has been provided by McElree, Traxler, Pickering, Seely, & Jackendoff (2001). In the present study, however, in two self-paced reading experiments, type-shifting effects (taken to be longer reading times engendered by the computation of the coercion process) were not obtained with sentences in isolation (Experiment 1) or with sentences embedded in contexts that specified the nature of the activity performed over the complement NP (Experiment 2). It is argued that type-shifting verbs are similar to non-preferred verbs for given contexts and that type-shifting operations are pragmatic inferences computed over underspecified semantic representations.     

Imageability and distributional typicality measures of nouns and verbs in contemporary English

Dissociations between noun and verb processing are not uncommon after brain injury; yet, precise psycholinguistic comparisons of nouns and verbs are hampered by the underrepresentation of verbs in published semantic word norms and by the absence of contemporary estimates for part-of-speech usage. We report herein imageability ratings and rating response times (RTs) for 1,197 words previously categorized as pure nouns, pure verbs, or words of balanced noun-verb usage on the basis of the Francis and Ku?era (1982) norms. Nouns and verbs differed in rated imageability, and there was a stronger correspondence between imageability rating and RT for nouns than for verbs. For all word types, the image-rating-RT function implied that subjects employed an image generation process to assign ratings. We also report a new measure of noun-verbtypicality that used the Hyperspace Analog to Language (HAL; Lund & Burgess, 1996) context vectors (derived from a large sample of Usenet text) to compute the mean context distance between each word and all of thepure nouns andpure verbs. For a subset of the items, the resulting HAL noun-verb difference score was compared with part-of-speech usage in a representative sample of the Usenet corpus. It is concluded that this score can be used to estimate the extent to which a given word occurs in typical noun or verb sentence contexts in informal contemporary English discourse. The item statistics given in Appendix B will enable experimenters to select representative examples of nouns and verbs or to compare typical with atypical nouns (or verbs), while holding constant or covarying rated imageability.     

The retention of nouns,adjectives, and verbs of sentences

This research compared the retention of nouns, adjectives and verbs of sentences. A model of the structure underlying the retention of sentences and in which deep structure constituent propositions are hierarchically related, was used to make predictions concerning the retention of these word classes. The model was not supported by the data and it was determined that latencies to recognize the words of a previously presented sentence were the same for all classes of words. This result indicated that for recognition (but not necessarily for other memory tasks), each word of a sentence is seperately or equally accessible (as long as inter-word imagery is the same). However, a further experiment showed that, although word class is not a variable, the image-arousing capacity of a word is. Latencies and error rates were much lower for high-imagery words than for low-imagery ones. The findings on error rates in recognizing words were interesting and pointed to a different model where the meaning representations and syntatic functions of words have an active role in sentence retention.     

Asymmetries for the categorization of kanji nouns, adjectives, and verbs presented to the left and right

Kanji is one form of written Japanese in which the symbolic/analytic characteristics of language are dissociated from systematic phonetic characteristics; as such, it makes possible a more careful test of which aspect of language is responsible for the frequently observed superior left-hemisphere performance. In this study, subjects were asked to categorize tachistoscopically presented kanji as nouns, adjectives, or verbs. The previously reported (Hatta 1977, Neuropsychologia, 15, 685–688) left-visual-field advantage for kanji was found only in the case of nouns. Adjectives and verbs were processed more rapidly and correctly in the right visual field.     

Priming nouns and verbs: differential influences of semantic and grammatical cues in the two cerebral hemispheres

The current experiment investigated how sentential form-class expectancies influenced lexical-semantic priming within each hemisphere. Sentences were presented that led readers to expect a noun or a verb and the sentence-final target word was presented to one visual field/hemisphere for a lexical decision response. Noun and verb targets in the semantically related condition were compared to an unrelated prime condition, which also predicted part of speech but did not contain any lexical-semantic associates of the target word. The semantic priming effect was strongly modulated by form-class expectancy for RVF/LH targets, for both nouns and verbs. In the LVF/RH, semantic priming was obtained in all conditions, regardless of whether the form-class expectancy was violated. However, the nouns that were preceded by a noun-predicting sentence showed an extremely high priming value in the LVF/RH, suggesting that the RH may have some sensitivity to grammatical predictions for nouns. Comparisons of LVF/RH priming to calculations derived from the LSA model of language representation, which does not utilize word order, suggested that the RH might derive message-level meaning primarily from lexical-semantic relatedness.     

Two-year-olds learn novel nouns,verbs, and conventional actions from massed or distributed exposures

Two-year-old children were taught either 6 novel nouns, 6 novel verbs, or 6 novel actions over 1 month. In each condition, children were exposed to some items in massed presentations (on a single day) and some in distributed presentations (over the 2 weeks). Children's comprehension and production was tested at 3 intervals after training. In comprehension, children learned all types of items in all training conditions at all retention intervals. For production, the main findings were that (a) production was better for nonverbal actions than for either word type, (b) children produced more new nouns than verbs, (c) production of words was better following distributed than massed exposure, and (d) time to testing (immediate, 1 day, 1 week) did not affect retention. A follow-up study showed that the most important timing variable was the number of different days of exposure, with more days facilitating production. Results are discussed in terms of 2 key issues: (a) the domain-generality versus domain-specificity of processes of word learning and (b) the relative ease with which children learn nouns versus verbs.