Syntactic priming of relative clause attachments: persistence of structural configuration in sentence production

Three sentence completion experiments will be reported in which participants had to generate German equivalents of "the servant of the actress who..." (NP-of-NP-RC) constructions. Target fragments (which were unconstrained as to whether the relative pronoun permitted high or low attachment) were preceded by constrained prime fragments, which were either structurally congruent with the targets (Experiments 1 and 2) or structurally incongruent with the targets (anaphoric adverbial clauses rather than relative clauses (RCs), Experiment 3). While the first two experiments established reliable repetition of RC attachments between primes and targets, Experiment 3 failed to obtain a significant priming effect, indicating that RC attachment priming is dependent on a syntactic overlap between primes and targets. The results suggest a tendency of language producers to retain hierarchical syntactic relations over consecutive trials. Current models of syntactic priming in production do not offer an explanatory mechanism for this kind of observation as they presently stand.     

Reading strategy modulates parafoveal-on-foveal effects in sentence reading

Task demands and individual differences have been linked reliably to word skipping during reading. Such differences in fixation probability may imply a selection effect for multivariate analyses of eye-movement corpora if selection effects correlate with word properties of skipped words. For example, with fewer fixations on short and highly frequent words the power to detect parafoveal-on-foveal effects is reduced. We demonstrate that increasing the fixation probability on function words with a manipulation of the expected difficulty and frequency of questions reduces an age difference in skipping probability (i.e., old adults become comparable to young adults) and helps to uncover significant parafoveal-on-foveal effects in this group of old adults. We discuss implications for the comparison of results of eye-movement research based on multivariate analysis of corpus data with those from display-contingent manipulations of target words.     

It's in the sample: the effects of sample size and sample diversity on the breadth of inductive generalization

Developmental studies have provided mixed evidence with regard to the question of whether children consider sample size and sample diversity in their inductive generalizations. Results from four experiments with 105 undergraduates, 105 school-age children (M = 7.2 years), and 105 preschoolers (M = 4.9 years) showed that preschoolers made a higher rate of projections from large samples than from small samples when samples were diverse (Experiments 1 and 3) but not when samples were homogeneous (Experiment 4) and not when the task required a choice between two samples (Experiment 2). Furthermore, when a property occurred in large and diverse samples, preschoolers exhibited a broad pattern of projection, generalizing the property to items from categories not represented in the evidence. In contrast, adults followed a normative pattern of induction and never attributed properties to items from categories not represented in the evidence. School-age children showed a mixed pattern of results.     

The cognitive implications of asymmetric color generalization in honeybees

Generalization occurs when a conditioned response formed to one stimulus is also elicited by other stimuli which have not been used in the course of conditioning. Here, we studied color generalization in honeybees Apis mellifera trained to two rewarded colors, S₁+ and S₂+. After training, bees were tested with non-rewarded novel stimuli, which lay between the trained stimuli in a honeybee color space (Int) or outside the range defined by the trained stimuli (E ₁ and E ₂). We analyzed whether bees interpolated their choice to Int and/or extrapolated it to E ₁ and E ₂. We compared the performances of the group trained with S₁+ and S₂+ to those of control groups trained only with S₁+ or S₂+. Bees trained with S₁+ and S₂+ responded similarly and highly to all test stimuli. These results do not allow discerning between generalization models based on the presence of interpolation and/or extrapolation. Nevertheless, bee’s performance was consistent with a linear summation of the two generalization gradients generated by S₁+ and S₂+, respectively. These gradients were asymmetric because control bees responded to the test stimuli as if these belonged to different similarity classes in spite of the fact that they had similar perceptual distances separating them. Stimuli treated as similar were located in the same half of the color spaces, whereas stimuli treated as different were located in opposite halves. Our results suggest that color categories could exist in honeybees and may underlie the performance of the control groups. Under this assumption, color categories would be also present in simpler nervous systems, and would not require factors such as language to be expressed.     

A positron emission tomography study of short- and long-term treatment effects on functional brain activation in adults who stutter

Previous studies have shown that fluency-inducing techniques, such as choral speech, result in changes in neural activation as measured by functional neuroimaging. In the present study, positron emission tomography was used to investigate the effects of intensive behavioural treatment, followed by a 1-year maintenance program, on the pattern of cortical and subcortical activation in stuttering adults during silent and oral reading of single words. The results indicate changes in activation lateralisation, as well as a general reduction in overactivation, especially in the motor cortex, following treatment. The results are discussed in light of previous functional imaging studies with stuttering adults.

Educational objectives: The reader will learn about and be able to describe the: (1) use of functional neuroimaging PET in the study of stuttering; (2) differences in neural activation between stuttering and non-stuttering adults; and (3) effects of behavioural fluency treatment on cortical and subcortical activations in stuttering speakers.     

Fear generalization in humans: Impact of prior non-fearful experiences

Fear generalization lies at the heart of many anxiety problems, and is therefore an important target for prevention and/or treatment. Here, we investigated whether fear generalization towards a specific stimulus can be weakened by prior non-fearful experiences with that stimulus. Using the standard human fear conditioning procedure, all participants received paired presentations of a geometric figure and an electric shock. This was followed by a test phase in which a similar but different figure was presented. Electrodermal responding and ratings of shock-expectancy measured the level of fear generalization towards this test stimulus. Crucially, half of the participants had been preexposed to that stimulus (without shock). The results show significantly less generalization in this group, suggesting that prior non-fearful experiences can protect against fear generalization. These results may inspire novel ways to prevent the development of clinical anxiety.     

A disadvantage in bilingual sentence production modulated by syntactic frequency and similarity across languages

Bilingual speakers access individual words less fluently, quickly, and accurately than monolinguals, particularly when accessing low-frequency words. Here we examined whether the bilingual speech production disadvantage would (a) extend to full sentences above and beyond single word retrieval and whether it would be modulated by (b) structural frequency and (c) syntactic properties of the bilingual speakers’ other language. English monolinguals, Spanish–English bilinguals and Mandarin–English bilinguals were tested in a sentence production task conducted exclusively in English. Response times were modulated by bilingualism, structural frequency, and structural similarity across the bilingual speakers’ two languages. These results refine our knowledge regarding the scope of the bilingual disadvantage, demonstrate that frequency effects apply to syntactic structures, and also suggest that syntax is partially shared across bilinguals’ two languages.     

Minimization of dependency length in written English

Gibson's Dependency Locality Theory (DLT) [Gibson, E. 1998. Linguistic complexity: locality of syntactic dependencies. Cognition, 68, 1-76; Gibson, E. 2000. The dependency locality theory: A distance-based theory of linguistic complexity. In A. Marantz, Y. Miyashita, & W. O'Neil (Eds.), Image, Language, Brain (pp. 95-126). Cambridge, MA: MIT Press.] proposes that the processing complexity of a sentence is related to the length of its syntactic dependencies: longer dependencies are more difficult to process. The DLT is supported by a variety of phenomena in language comprehension. This raises the question: Does language production reflect a preference for shorter dependencies as well? I examine this question in a corpus study of written English, using the Wall Street Journal portion of the Penn Treebank. The DLT makes a number of predictions regarding the length of constituents in different contexts; these predictions were tested in a series of statistical tests. A number of findings support the theory: the greater length of subject noun phrases in inverted versus uninverted quotation constructions, the greater length of direct-object versus subject NPs, the greater length of postmodifying versus premodifying adverbial clauses, the greater length of relative-clause subjects within direct-object NPs versus subject NPs, the tendency towards "short-long" ordering of postmodifying adjuncts and coordinated conjuncts, and the shorter length of subject NPs (but not direct-object NPs) in clauses with premodifying adjuncts versus those without.     

Dissociations and associations of performance in syntactic comprehension in aphasia and their implications for the nature of aphasic deficits

Sixty-one pwa were tested on syntactic comprehension in three tasks: sentence-picture matching, sentence-picture matching with auditory moving window presentation, and object manipulation. There were significant correlations of performances on sentences across tasks. First factors on which all sentence types loaded in unrotated factor analyses accounted for most of the variance in each task. Dissociations in performance between sentence types that differed minimally in their syntactic structures were not consistent across tasks. These results replicate previous results with smaller samples and provide important validation of basic aspects of aphasic performance in this area of language processing. They point to the role of a reduction in processing resources and of the interaction of task demands and parsing and interpretive abilities in the genesis of patient performance.     

Direct Evidence of Memory Retrieval as a Source of Difficulty in Non‐Local Dependencies in Language

Linguistic dependencies between non‐adjacent words have been shown to cause comprehension difficulty, compared with local dependencies. According to one class of sentence comprehension accounts, non‐local dependencies are difficult because they require the retrieval of the first dependent from memory when the second dependent is encountered. According to these memory‐based accounts, making the first dependent accessible at the time when the second dependent is encountered should help alleviate the difficulty associated with the processing of non‐local dependencies. In a dual‐task paradigm, participants read sentences that did or did not contain a non‐local dependency (i.e., object‐ and subject‐extracted cleft constructions) while simultaneously remembering a word. The memory task was aimed at making the word held in memory accessible throughout the sentence. In an object‐extracted cleft (e.g., It was Ellen whom John consulted…), the object (Ellen) must be retrieved from memory when consulted is encountered. In the critical manipulation, the memory word was identical to the verb's object (ELLEN). In these conditions, the extraction effect was reduced in the comprehension accuracy data and eliminated in the reading time data. These results add to the body of evidence supporting memory‐based accounts of syntactic complexity.     

The developing constraints on parsing decisions: the role of lexical-biases and referential scenes in child and adult sentence processing

Two striking contrasts currently exist in the sentence processing literature. First, whereas adult readers rely heavily on lexical information in the generation of syntactic alternatives, adult listeners in world-situated eye-gaze studies appear to allow referential evidence to override strong countervailing lexical biases (Tanenhaus, Spivey-Knowlton, Eberhard, and Sedivy, 1995). Second, in contrast to adults, children in similar listening studies fail to use this referential information and appear to rely exclusively on verb biases or perhaps syntactically based parsing principles (Trueswell, Sekerina, Hill, and Logrip, 1999). We explore these contrasts by fully crossing verb bias and referential manipulations in a study using the eye-gaze listening technique with adults (Experiment 1) and five-year-olds (Experiment 2). Results indicate that adults combine lexical and referential information to determine syntactic choice. Children rely exclusively on verb bias in their ultimate interpretation. However, their eye movements reveal an emerging sensitivity to referential constraints. The observed changes in information use over ontogenetic time best support a constraint-based lexicalist account of parsing development, which posits that highly reliable cues to structure, like lexical biases, will emerge earlier during development and more robustly than less reliable cues.     

Learning to divide the labor: an account of deficits in light and heavy verb production

Theories of sentence production that involve a convergence of activation from conceptual‐semantic and syntactic‐sequential units inspired a connectionist model that was trained to produce simple sentences. The model used a learning algorithm that resulted in a sharing of responsibility (or “division of labor”) between syntactic and semantic inputs for lexical activation according to their predictive power. Semantically rich, or “heavy”, verbs in the model came to rely on semantic cues more than on syntactic cues, whereas semantically impoverished, or “light”, verbs relied more on syntactic cues. When the syntactic and semantic inputs were lesioned, the model exhibited patterns of production characteristic of agrammatic and anomic aphasic patients, respectively. Anomic models tended to lose the ability to retrieve heavy verbs, whereas agrammatic models were more impaired in retrieving light verbs. These results obtained in both sentence production and single‐word naming simulations. Moreover, simulated agrammatic lexical retrieval was more impaired overall in sentences than in single‐word tasks, in agreement with the literature. The results provide a demonstration of the division‐of‐labor principle, as well as general support for the claim that connectionist learning principles can contribute to the understanding of non‐transparent neuropsychological dissociations.     

On the parity of structural persistence in language production and comprehension

Structural priming creates structural persistence. That is, differences in experience with syntax can change subsequent language performance, and the changes can be observed in both language production and comprehension. However, the effects in comprehension and production appear to differ. In comprehension, persistence is typically found when the verbs are the same in primes and targets; in production, persistence occurs without verb overlap. The contrast suggests a theoretically important hypothesis: parsing in comprehension is lexically driven while formulation in production is structurally driven. A major weakness in this hypothesis about comprehension-production differences is that its empirical motivation rests on the outcomes of experiments in which the priming manipulations differ, the primed sentence structures differ, and the measures of priming differ. To sharpen the comparison, we examined structural persistence with and without verb overlap in both reading comprehension and spoken production, using the same prime presentation procedure, the same syntactic structures, the same sentences, and the same participants. These methods yielded abstract structural persistence in comprehension as well as production. A measure of the strength of persistence revealed significant effects of priming and verb overlap without significant comprehension—production differences. This argues for uniformity in the structural mechanisms of language processing.     

Word order in sentence processing: an experimental study of verb placement in German

We examine the question of whether the human comprehension device exhibits word-order preferences during on-line sentence comprehension. The focus is on the positioning of finite verbs and auxiliaries relative to subjects and objects in German. Results from three experiments (using self-paced reading and event-related brain potentials) show that native speakers of German prefer to process finite verbs in second position (i.e., immediately after the subject and before the object). We will account for this order preference in terms of the relative processing costs associated with SV_fO and SOV_f. Our finding that word-order preferences play an important role in the on-line comprehension of German sentences is compatible with results from previous studies on English and other languages.     

The patterns of silence: Performance structures in sentence production

The pauses produced by speakers while reading familiar material were used to obtain hierarchical sentence structures. Identical structures were obtained from parsing, indicating that the performance structures of sentences are not task specific. The linguistic surface structure of a sentence is a good predictor of the pause durations. However, speakers also revealed a tendency to place pauses between segments of equal length. A simple cyclical model combining, for each pause location, an index of linguistic complexity and a measure of the distance to the midpoint of the segment, accounts for 72% of the pause time variance as opposed to 56% for the linguistic index alone. The generality of the model is shown by its good prediction of the pause durations obtained in unrelated studies in English and American Sign Language.     

Neural network processing of natural language: II. Towards a unified model of corticostriatal function in learning sentence comprehension and non-linguistic sequencing

A central issue in cognitive neuroscience today concerns how distributed neural networks in the brain that are used in language learning and processing can be involved in non-linguistic cognitive sequence learning. This issue is informed by a wealth of functional neurophysiology studies of sentence comprehension, along with a number of recent studies that examined the brain processes involved in learning non-linguistic sequences, or artificial grammar learning (AGL). The current research attempts to reconcile these data with several current neurophysiologically based models of sentence processing, through the specification of a neural network model whose architecture is constrained by the known cortico-striato-thalamo-cortical (CSTC) neuroanatomy of the human language system. The challenge is to develop simulation models that take into account constraints both from neuranatomical connectivity, and from functional imaging data, and that can actually learn and perform the same kind of language and artificial syntax tasks. In our proposed model, structural cues encoded in a recurrent cortical network in BA47 activate a CSTC circuit to modulate the flow of lexical semantic information from BA45 to an integrated representation of meaning at the sentence level in BA44/6. During language acquisition, corticostriatal plasticity is employed to allow closed class structure to drive thematic role assignment. From the AGL perspective, repetitive internal structure in the AGL strings is encoded in BA47, and activates the CSTC circuit to predict the next element in the sequence. Simulation results from Caplan's [Caplan, D., Baker, C., & Dehaut, F. (1985). Syntactic determinants of sentence comprehension in aphasia. Cognition, 21, 117-175] test of syntactic comprehension, and from Gomez and Schvaneveldts' [Gomez, R. L., & Schvaneveldt, R. W. (1994). What is learned from artificial grammars?. Transfer tests of simple association. Journal of Experimental Psychology: Learning, Memory and Cognition, 20, 396-410] artificial grammar learning experiments are presented. These results are discussed in the context of a brain architecture for learning grammatical structure for multiple natural languages, and non-linguistic sequences.