GEMINI: A Natural Language System for Spoken-Language Understanding

Gemini is a natural language understanding system developed for spoken language applications. The paper describes the architecture of Gemini, paying particular attention to resolving the tension between robustness and overgeneration. Gemini features a broad-coverage unification-based grammar of English, fully interleaved syntactic and semantic processing in an all-paths, bottom-up parser, and an utterance-level parser to find interpretations of sentences that might not be analyzable as complete sentences. Gemini also includes novel components for recognizing and correcting grammatical disfluencies, and for doing parse preferences. This paper presents a component-by-component view of Gemini, providing detailed relevant measurements of size, efficiency, and performance.Comment: 8 pages, postscrip

(In)variability in the Samoan syntax/prosody interface and consequences for syntactic parsing

While it has long been clear that prosody should be part of the grammar influencing the action of the syntactic parser, how to bring prosody into computational models of syntactic parsing has remained unclear. The challenge is that prosodic information in the speech signal is the result of the interaction of a multitude of conditioning factors. From this output, how can we factor out the contribution of syntax to conditioning prosodic events? And if we are able to do that factorization and define a production model from the syntactic grammar to a prosodified utterance, how can we then define a comprehension model based on that production model? In this case study of the Samoan morphosyntax-prosody interface, we show how to factor out the influence of syntax on prosody in empirical work and confirm there is invariable morphosyntactic conditioning of high edge tones. Then, we show how this invariability can be precisely characterized and used by a parsing model that factors the various influences of morphosyntax on tonal events. We expect that models of these kinds can be extended to more comprehensive perspectives on Samoan and to languages where the syntax/prosody coupling is more complex

The Interplay Of Syntactic Parsing Strategies And Prosodic Phrase Lengths In Processing Turkish Sentences

Many experiments have shown that the prosody (rhythm and melody) with which a sentence is uttered can provide a listener with cues to its syntactic structure (Lehiste, 1973, and since). A few studies have observed in addition that an inappropriate prosodic contour can mislead the syntactic parsing routines, resulting in a prosody-induced garden-path. These include, among others, Speer et al. (1996) and Kjelgaard and Speer (1999) for English. The studies by Speer et al. and Kjelgaard and Speer (SKS) showed that misplaced prosodic cues caused more processing difficulty in sentences with early closure of a clause (EC syntax) than in ones with late closure of a clause (LC syntax). One possible explanation for these results is that when prosody is misleading about the syntactic structure, the parser may ignore it and resort to a syntactic Late Closure strategy, as it does in reading where there is no overt prosodic boundary to inform the parser about the syntactic structure of the sentence. Augurzky\u27s (2006) observation of an LC syntax advantage for prosody-syntax mismatch conditions in her investigation of German relative clause attachment ambiguities provides support for this explanation. An alternative explanation considers the possibility that constituent lengths could have influenced the perceived informativeness of overt prosodic cues in these studies, as proposed in the Rational Speaker Hypothesis of Clifton et al. (2002, 2006). The Rational Speaker Hypothesis (RSH) maintains that prosodic breaks flanking shorter constituents are taken more seriously as indicators of syntactic structure than prosodic breaks flanking longer constituents, because the former cannot be justified as motivated by optimal length considerations. To test these two alternative hypotheses, four listening experiments were conducted. There was an additional reading experiment preceding the listening experiments to explore potential effects of the Late Closure strategy and constituent lengths in reading where there is no overt prosody. In all cases the target materials were temporarily ambiguous Turkish sentences which could be morphologically resolved as either LC or EC syntactic constructions. Constituent lengths were systematically manipulated in all target materials, such that the length-optimal prosodic phrasing was associated with LC syntax in one condition, and with EC syntax in the other. Experiment 1 employed a missing morpheme task developed for this study. In the missing morpheme task, underscores (length-averaged) replaced the disambiguating morphemes and participants had to insert them as they read the sentences aloud. Results revealed significant effects of phrase lengths in readers\u27 syntactic interpretations as indicated by the morphemes they inserted and the prosodic breaks they produced. Experiments 2A and 2B employed an end-of-sentence `got it\u27 task (Frazier et al., 1983), in which participants listened to spoken sentences and indicated after each one whether they understood or did not understand it. Sentences in Experiment 2A had phrase length distribution similar to the SKS English materials. Experiment 2B manipulated lengths in reverse. The stimuli had cooperating, conflicting or neutral prosody. Response time data supported an interplay of both syntactic Late Closure and RSH. Thus it was concluded that constituent lengths can indeed have a significant effect on listeners\u27 parsing decisions, in addition to the familiar syntactic parsing biases and prosodic influences. Experiments 3A and 3B used a lexical probe version of the phoneme restoration paradigm employed by Stoyneshka et al. (2010). In the phoneme restoration paradigm, the disambiguating phonemes (in the verb, in these materials) are replaced with noise (in this study, pink noise). In the lexical probe version of this paradigm (developed for this study) participants listened to the sentences with LC, EC or neutral prosody, and at the end of the sentence they were presented with a visual probe (one of the two possible disambiguating verbs, complete with all phonemes) that was congruent or incongruent or compatible with the prosody of the sentence they had heard. Their task was to respond to the visual probe either `yes\u27 (i.e., `I heard this word in the sentence I have just listened to\u27) or `no\u27 (i.e., `I didn\u27t hear this word\u27). Response time to the probe word indirectly taps which of the disambiguating morphemes on the verb the listener mentally supplies when it has been replaced by noise. The materials for Experiments 3A and 3B were identical to those used in Experiments 2A and 2B respectively except that the disambiguating phonemes were noise-replaced. Results of Experiments 3A and 3B showed that listeners were highly sensitive to the sentential prosody as revealed by their phoneme restoration responses and response time data, confirming Stoyneshka et al.\u27s findings establishing the reliability of the phoneme restoration paradigm in investigating effects of prosody in ambiguity resolution. Response time data showed a pattern similar to what SKS observed for English (except for one condition in Experiment 3A, with incongruent probes): despite the phrase length reversal in Experiment 3B, there was no influence of phrase length distribution on ambiguity resolution. This has a natural explanation in light of the difference between the `got it\u27 task with disambiguating morphology within the sentence stimulus, and the phoneme restoration task in which the listener can project onto the verb whatever morphology is compatible with the heard prosody. LC and EC were processed equally well for congruent probes, and there was an LC advantage in the incongruent and compatible probe conditions. Overall results support the hypothesis that syntactic Late Closure becomes evident in listening when prosody is absent or misleading, and also that phrase lengths can play a significant role

Morphological word structure in English and Swedish : the evidence from prosody

Trubetzkoy's recognition of a delimitative function of phonology, serving to signal boundaries between morphological units, is expressed in terms of alignment constraints in Optimality Theory, where the relevant constraints require specific morphological boundaries to coincide with phonological structure (Trubetzkoy 1936, 1939, McCarthy & Prince 1993). The approach pursued in the present article is to investigate the distribution of phonological boundary signals to gain insight into the criteria underlying morphological analysis. The evidence from English and Swedish suggests that necessary and sufficient conditions for word-internal morphological analysis concern the recognizability of head constituents, which include the rightmost members of compounds and head affixes. The claim is that the stability of word-internal boundary effects in historical perspective cannot in general be sufficiently explained in terms of memorization and imitation of phonological word form. Rather, these effects indicate a morphological parsing mechanism based on the recognition of word-internal head constituents. Head affixes can be shown to contrast systematically with modifying affixes with respect to syntactic function, semantic content, and prosodic properties. That is, head affixes, which cannot be omitted, often lack inherent meaning and have relatively unmarked boundaries, which can be obscured entirely under specific phonological conditions. By contrast, modifying affixes, which can be omitted, consistently have inherent meaning and have stronger boundaries, which resist prosodic fusion in all phonological contexts. While these correlations are hardly specific to English and Swedish it remains to be investigated to which extent they hold cross-linguistically. The observation that some of the constituents identified on the basis of prosodic evidence lack inherent meaning raises the issue of compositionality. I will argue that certain systematic aspects of word meaning cannot be captured with reference to the syntagmatic level, but require reference to the paradigmatic level instead. The assumption is then that there are two dimensions of morphological analysis: syntagmatic analysis, which centers on the criteria for decomposing words in terms of labelled constituents, and paradigmatic analysis, which centers on the criteria for establishing relations among (whole) words in the mental lexicon. While meaning is intrinsically connected with paradigmatic analysis (e.g. base relations, oppositeness) it is not essential to syntagmatic analysis

Placing pauses in read spoken Spanish : a model and an algorithm

The purpose of this work is to describe the appearance and location of typographically unmarked pauses in any Spanish text to be read. An experiment is designed to derive pause location from natural speech: results show that Intonation Group length constraints guide the appearance of pauses, which are placed depending on syntactic information. Then, a rule-based algorithm is developed to automatically place pauses whose performance is tested by means of qualitative tests. The evaluation shows that the system adequately places pauses in read texts, since it predicts 81% of orthographically unmarked pauses; when pauses associated to punctuation signs are included, the percentage of correct prediction increases to 92%

Psycholinguistics is definitely tied up to prosody

For almost two decades, phonologists, phoneticians and psycholinguists have devoted attention to the value of prosodic information during silent reading. Until then information on the influence of syntactic and semantic aspects in silent reading was the focus of attention in Psycholinguistics. Despite the joint efforts of researchers, there are many issues to be explored regarding two main domains. The first relates to individual prosodic parameters to languages that can have influence on the processing of sentences. The second refers to how the parser uses the prosodic information present in written stimulus on the understanding of silently reading. In both situations, it will be necessary to focus on methodological aspects in addition to theoretical ones. If on the one hand we already have strong evidence about the influence of prosody in silent reading, on the other hand it cannot be denied that measuring the prosody mentally organized by the reader during reading process is not an easy task. Thus, this article intends to emphasize the complexity concerning the theme and at the same time the needs for further investigation in each language alone. It presents some insights from the early researches in Portuguese language and offers some suggestions for future investigation

Local and Universal

Cuetos and Mitchell 1988, and much subsequent work, report that speakers of different languages differ in Relative Clause attachment preferences in complex NPs. These findings challenged universal theories of processing and in particular the universality of locality in parsing. In this paper, I argue that asymmetries in attachment preference stem from a previously unnoticed grammatical distinction: the availability of Pseudo Relatives. Drawing on previous data and novel results, I conclude that Locality is a genuine universal principle of processing

Prepositional Phrase Attachment Ambiguities in Declarative and Interrogative Contexts: Oral Reading Data

Certain English sentences containing multiple prepositional phrases (e.g., She had planned to cram the paperwork in the drawer into her briefcase) have been reported to be prone to mis-parsing of a kind that is standardly called a “garden path.” The mis-parse stems from the temporary ambiguity of the first prepositional phrase (PP1: in the drawer), which tends to be interpreted initially as the goal argument of the verb cram. If the sentence ended there, that would be correct. But that analysis is overridden when the second prepositional phrase (PP2: into her briefcase) is encountered, since the into phrase can only be interpreted as the goal argument of the verb. Thus, PP2 necessarily supplants PP1’s initially assigned position as goal, and PP1 must be reanalyzed as a modifier of the object NP (the paperwork). Interrogative versions of the same sentence structure (Had she planned to cram the paperwork in the drawer into her briefcase?) may have a different profile. They have been informally judged to be easier to process than their declarative counterparts, because they are less susceptible to the initial garden path analysis. The study presented here represents an attempt to find a behavioral correlate of this intuitive difference in processing difficulty. The experiment employs the Double Reading Paradigm (Fodor, Macaulay, Ronkos, Callahan, and Peckenpaugh, 2019). Participants were asked to read aloud a visually presented sentence twice, first without taking any time at all to preview the sentence content (Reading 1), and then again after unlimited preview (Reading 2). The experimental items were created in a 2 x 2 design with one factor being Speech Act (declarative vs. interrogative) and the other being PP2 Status, i.e., PP2 could only be an argument of the verb iv (Arg), as above, or else PP2 could be interpreted as a modifier (Mod) of the NP within the preceding PP, as in She had / Had she planned to cram the paperwork in the drawer of her filing cabinet(?). Participants’ recordings of Reading 1 and Reading 2 were subjected to prosodic coding by a linguist who was naive to the research question. Distributions of prosodic boundaries were statistically analyzed to extract any significant differences in prosodic boundary patterns as a function of Speech Act, Reading, or PP2 Status. Logistic mixed effect regression models indicated, as anticipated, a significant effect of PP2 Status across all analyses of prosodic phrasing, and a significant effect of Reading for both analyses of prosodic phrasing that included boundary strength. Speech Act was a significant predictor in one of prosodic phrasing, but the hypothesized interaction (between Speech Act and PP2 Status) was not significant in any model. Another analysis concerned the amount of time a participant spent silently studying a sentence after Reading 1 to be confident they had understood it before reading it aloud again (Reading 2). The time between readings is referred to as the inter-reading time (IRT). It was assumed that a longer IRT signifies greater processing difficulty of the sentence. Thus, IRT was hypothesized to provide a behavioral correlate of the intuitive judgement that the interrogative garden paths are easier to process than the declarative ones. If a correlate had been found, it would have taken the form of an interaction between the two factors (Speech Act and PP2 Status) such that the IRT difference between Arg and Mod sentence versions was smaller for interrogatives than for declaratives. Ultimately, however, no statistically significant interaction between Speech Act and PP2 Status was found. Further studies seeking behavioral evidence of the informal intuition motivating this research are proposed. Also offered are possible explanations for why the intuition is apparently so strong for some English speakers, and why, if so, it is not reflected in IRT. Significant ancillary findings are that interrogatives are in general more difficult to process than corresponding declaratives. Also, inter-reading time (IRT) in the Double Reading paradigm is confirmed as a useful measure of sentence processing difficulty given that within the declarative sentences, the garden-path (Arg) versions showed significantly longer IRTs than the non-garden-path (Mod) versions

Stochastic phonological grammars and acceptability

In foundational works of generative phonology it is claimed that subjects can reliably discriminate between possible but non-occurring words and words that could not be English. In this paper we examine the use of a probabilistic phonological parser for words to model experimentally-obtained judgements of the acceptability of a set of nonsense words. We compared various methods of scoring the goodness of the parse as a predictor of acceptability. We found that the probability of the worst part is not the best score of acceptability, indicating that classical generative phonology and Optimality Theory miss an important fact, as these approaches do not recognise a mechanism by which the frequency of well-formed parts may ameliorate the unacceptability of low-frequency parts. We argue that probabilistic generative grammars are demonstrably a more psychologically realistic model of phonological competence than standard generative phonology or Optimality Theory.Comment: compressed postscript, 8 pages, 1 figur