TY - JOUR A1 - Patil, Umesh A1 - Hanne, Sandra A1 - Burchert, Frank A1 - De Bleser, Ria A1 - Vasishth, Shravan T1 - A Computational Evaluation of Sentence Processing Deficits in Aphasia JF - Cognitive science : a multidisciplinary journal of anthropology, artificial intelligence, education, linguistics, neuroscience, philosophy, psychology ; journal of the Cognitive Science Society N2 - Individuals with agrammatic Broca's aphasia experience difficulty when processing reversible non-canonical sentences. Different accounts have been proposed to explain this phenomenon. The Trace Deletion account (Grodzinsky, 1995, 2000, 2006) attributes this deficit to an impairment in syntactic representations, whereas others (e.g., Caplan, Waters, Dede, Michaud, & Reddy, 2007; Haarmann, Just, & Carpenter, 1997) propose that the underlying structural representations are unimpaired, but sentence comprehension is affected by processing deficits, such as slow lexical activation, reduction in memory resources, slowed processing and/or intermittent deficiency, among others. We test the claims of two processing accounts, slowed processing and intermittent deficiency, and two versions of the Trace Deletion Hypothesis (TDH), in a computational framework for sentence processing (Lewis & Vasishth, 2005) implemented in ACT-R (Anderson, Byrne, Douglass, Lebiere, & Qin, 2004). The assumption of slowed processing is operationalized as slow procedural memory, so that each processing action is performed slower than normal, and intermittent deficiency as extra noise in the procedural memory, so that the parsing steps are more noisy than normal. We operationalize the TDH as an absence of trace information in the parse tree. To test the predictions of the models implementing these theories, we use the data from a German sentence—picture matching study reported in Hanne, Sekerina, Vasishth, Burchert, and De Bleser (2011). The data consist of offline (sentence-picture matching accuracies and response times) and online (eye fixation proportions) measures. From among the models considered, the model assuming that both slowed processing and intermittent deficiency are present emerges as the best model of sentence processing difficulty in aphasia. The modeling of individual differences suggests that, if we assume that patients have both slowed processing and intermittent deficiency, they have them in differing degrees. KW - Aphasia KW - Non-canonical sentences KW - Sentence-picture matching KW - Eye movements KW - Computational modeling KW - Cognitive architecture KW - Individual differences Y1 - 2016 U6 - https://doi.org/10.1111/cogs.12250 SN - 0364-0213 SN - 1551-6709 VL - 40 SP - 5 EP - 50 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Sorensen, Tanner A1 - Hohenstein, Sven A1 - Vasishth, Shravan T1 - Bayesian linear mixed models using Stan: A tutorial for psychologists, linguists, and cognitive scientists JF - Tutorials in Quantitative Methods for Psychology N2 - With the arrival of the R packages nlme and lme4, linear mixed models (LMMs) have come to be widely used in experimentally-driven areas like psychology, linguistics, and cognitive science. This tutorial provides a practical introduction to fitting LMMs in a Bayesian framework using the probabilistic programming language Stan. We choose Stan (rather than WinBUGS or JAGS) because it provides an elegant and scalable framework for fitting models in most of the standard applications of LMMs. We ease the reader into fitting increasingly complex LMMs, using a two-condition repeated measures self-paced reading study. KW - Bayesian data analysis KW - linear mixed models Y1 - 2016 U6 - https://doi.org/10.20982/tqmp.12.3.p175 SN - 2292-1354 VL - 12 SP - 175 EP - 200 PB - University of Montreal, Department of Psychology CY - Montreal ER - TY - JOUR A1 - Logacev, Pavel A1 - Vasishth, Shravan T1 - A Multiple-Channel Model of Task-Dependent Ambiguity Resolution in Sentence Comprehension JF - Cognitive science : a multidisciplinary journal of anthropology, artificial intelligence, education, linguistics, neuroscience, philosophy, psychology ; journal of the Cognitive Science Society N2 - Traxler, Pickering, and Clifton (1998) found that ambiguous sentences are read faster than their unambiguous counterparts. This so-called ambiguity advantage has presented a major challenge to classical theories of human sentence comprehension (parsing) because its most prominent explanation, in the form of the unrestricted race model (URM), assumes that parsing is non-deterministic. Recently, Swets, Desmet, Clifton, and Ferreira (2008) have challenged the URM. They argue that readers strategically underspecify the representation of ambiguous sentences to save time, unless disambiguation is required by task demands. When disambiguation is required, however, readers assign sentences full structure—and Swets et al. provide experimental evidence to this end. On the basis of their findings, they argue against the URM and in favor of a model of task-dependent sentence comprehension. We show through simulations that the Swets et al. data do not constitute evidence for task-dependent parsing because they can be explained by the URM. However, we provide decisive evidence from a German self-paced reading study consistent with Swets et al.'s general claim about task-dependent parsing. Specifically, we show that under certain conditions, ambiguous sentences can be read more slowly than their unambiguous counterparts, suggesting that the parser may create several parses, when required. Finally, we present the first quantitative model of task-driven disambiguation that subsumes the URM, and we show that it can explain both Swets et al.'s results and our findings. KW - Sentence processing KW - Ambiguity KW - Parallel processing KW - Cognitive modeling KW - Unrestricted race model KW - URM KW - Underspecification KW - Good-enough processing Y1 - 2016 U6 - https://doi.org/10.1111/cogs.12228 SN - 0364-0213 SN - 1551-6709 VL - 40 SP - 266 EP - 298 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Frank, Stefan L. A1 - Trompenaars, Thijs A1 - Vasishth, Shravan T1 - Cross-Linguistic Differences in Processing Double-Embedded Relative Clauses: Working-Memory Constraints or Language Statistics? JF - Cognitive science : a multidisciplinary journal of anthropology, artificial intelligence, education, linguistics, neuroscience, philosophy, psychology ; journal of the Cognitive Science Society N2 - An English double-embedded relative clause from which the middle verb is omitted can often be processed more easily than its grammatical counterpart, a phenomenon known as the grammaticality illusion. This effect has been found to be reversed in German, suggesting that the illusion is language specific rather than a consequence of universal working memory constraints. We present results from three self-paced reading experiments which show that Dutch native speakers also do not show the grammaticality illusion in Dutch, whereas both German and Dutch native speakers do show the illusion when reading English sentences. These findings provide evidence against working memory constraints as an explanation for the observed effect in English. We propose an alternative account based on the statistical patterns of the languages involved. In support of this alternative, a single recurrent neural network model that is trained on both Dutch and English sentences is shown to predict the cross-linguistic difference in the grammaticality effect. KW - Bilingualism KW - Cross-linguistic differences KW - Sentence comprehension KW - Relative clauses KW - Centre embedding KW - Grammaticality illusion KW - Self-paced reading KW - Recurrent neural network model Y1 - 2016 U6 - https://doi.org/10.1111/cogs.12247 SN - 0364-0213 SN - 1551-6709 VL - 40 SP - 554 EP - 578 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Hanne, Sandra A1 - Burchert, Frank A1 - Vasishth, Shravan T1 - On the nature of the subject-object asymmetry in wh-question comprehension in aphasia: evidence from eye tracking JF - Aphasiology : an international, interdisciplinary journal N2 - Background: Individuals with aphasia (IWA) show deficits in comprehending object-extracted declaratives while comprehension of subject-extracted structures is relatively preserved. It is a matter of debate whether this subject–object asymmetry also arises for comprehension of wh-questions. Successful comprehension of wh-questions critically entails correct resolution of a filler–gap dependency. Most previous studies have used only offline accuracy measures to investigate wh-question comprehension in aphasia. Online studies exploring syntactic processing in real time are needed in order to draw inferences about gap-filling abilities in IWA and to identify the point of breakdown in sentence comprehension. Aims: This study aimed at investigating processing of subject and object who-questions in German-speaking IWA and in a group of controls by combining an offline and online method. We further aimed to explore the impact of case-marking cues on processing of wh-questions. Methods & Procedures: Applying a variant of the visual world eye-tracking paradigm, we measured participants’ eye movements while they performed the same offline task, which is frequently used to assess comprehension of declaratives (sentence–picture matching). Outcomes & Results: Concerning online processing of who-questions in controls, we found anticipation of the most likely post-verbal theta-role immediately after processing the case-marked wh-pronoun in both subject and object questions. In addition, we observed an unexpected advantage of object over subject questions in terms of processing time. The offline results for IWA revealed that there were three heterogeneous patterns: (a) symmetrical comprehension with equal impairments for both question types, (b) asymmetrical performance with better comprehension of subject than object who-questions, and (c) a reversed asymmetry with better comprehension of object as compared to subject questions. For online processing of both types of who-questions, IWA showed retained abilities in postulating the gap and in associating the filler with this gap, although they were slower as compared to controls. Moreover, similarly to controls, they anticipated the most likely post-verbal theta-role. Conclusions: For controls, the findings provide evidence for rapid resolution of the filler–gap dependency and incremental processing of case-marking cues, reflected in early prediction of upcoming syntactic structure. We attribute faster processing of object questions to faster alignment of the anticipated element with a semantically more salient character. For IWA, the online data provide evidence for retained predictive abilities in processing of filler–gap dependencies in wh-questions, but prediction was delayed. This is most likely attributed to delayed integration of case-marking cues. KW - wh-questions KW - subject-object asymmetry KW - sentence comprehension deficits KW - online sentence processing KW - anticipatory eye movements Y1 - 2016 U6 - https://doi.org/10.1080/02687038.2015.1065469 SN - 0268-7038 SN - 1464-5041 VL - 30 SP - 435 EP - 462 PB - American Chemical Society CY - Abingdon ER - TY - JOUR A1 - Logacev, Pavel A1 - Vasishth, Shravan T1 - Understanding underspecification: A comparison of two computational implementations JF - The quarterly journal of experimental psychology N2 - Swets et al. (2008. Underspecification of syntactic ambiguities: Evidence from self-paced reading. Memory and Cognition, 36(1), 201–216) presented evidence that the so-called ambiguity advantage [Traxler et al. (1998 Traxler, M. J., Pickering, M. J., & Clifton, C. (1998). Adjunct attachment is not a form of lexical ambiguity resolution. Journal of Memory and Language, 39(4), 558–592. doi: 10.1006/jmla.1998.2600[CrossRef], [Web of Science ®], [Google Scholar]). Adjunct attachment is not a form of lexical ambiguity resolution. Journal of Memory and Language, 39(4), 558–592], which has been explained in terms of the Unrestricted Race Model, can equally well be explained by assuming underspecification in ambiguous conditions driven by task-demands. Specifically, if comprehension questions require that ambiguities be resolved, the parser tends to make an attachment: when questions are about superficial aspects of the target sentence, readers tend to pursue an underspecification strategy. It is reasonable to assume that individual differences in strategy will play a significant role in the application of such strategies, so that studying average behaviour may not be informative. In order to study the predictions of the good-enough processing theory, we implemented two versions of underspecification: the partial specification model (PSM), which is an implementation of the Swets et al. proposal, and a more parsimonious version, the non-specification model (NSM). We evaluate the relative fit of these two kinds of underspecification to Swets et al.’s data; as a baseline, we also fitted three models that assume no underspecification. We find that a model without underspecification provides a somewhat better fit than both underspecification models, while the NSM model provides a better fit than the PSM. We interpret the results as lack of unambiguous evidence in favour of underspecification; however, given that there is considerable existing evidence for good-enough processing in the literature, it is reasonable to assume that some underspecification might occur. Under this assumption, the results can be interpreted as tentative evidence for NSM over PSM. More generally, our work provides a method for choosing between models of real-time processes in sentence comprehension that make qualitative predictions about the relationship between several dependent variables. We believe that sentence processing research will greatly benefit from a wider use of such methods. KW - Computational modelling KW - Underspecification KW - Shallow processing Y1 - 2016 U6 - https://doi.org/10.1080/17470218.2015.1134602 SN - 1747-0218 SN - 1747-0226 VL - 69 SP - 996 EP - 1012 PB - BioMed Central CY - Abingdon ER - TY - JOUR A1 - Patil, Umesh A1 - Vasishth, Shravan A1 - Lewis, Richard L. T1 - Retrieval Interference in Syntactic Processing: The Case of Reflexive Binding in English JF - Frontiers in psychology N2 - It has been proposed that in online sentence comprehension the dependency between a reflexive pronoun such as himself/herself and its antecedent is resolved using exclusively syntactic constraints. Under this strictly syntactic search account, Principle A of the binding theory—which requires that the antecedent c-command the reflexive within the same clause that the reflexive occurs in—constrains the parser's search for an antecedent. The parser thus ignores candidate antecedents that might match agreement features of the reflexive (e.g., gender) but are ineligible as potential antecedents because they are in structurally illicit positions. An alternative possibility accords no special status to structural constraints: in addition to using Principle A, the parser also uses non-structural cues such as gender to access the antecedent. According to cue-based retrieval theories of memory (e.g., Lewis and Vasishth, 2005), the use of non-structural cues should result in increased retrieval times and occasional errors when candidates partially match the cues, even if the candidates are in structurally illicit positions. In this paper, we first show how the retrieval processes that underlie the reflexive binding are naturally realized in the Lewis and Vasishth (2005) model. We present the predictions of the model under the assumption that both structural and non-structural cues are used during retrieval, and provide a critical analysis of previous empirical studies that failed to find evidence for the use of non-structural cues, suggesting that these failures may be Type II errors. We use this analysis and the results of further modeling to motivate a new empirical design that we use in an eye tracking study. The results of this study confirm the key predictions of the model concerning the use of non-structural cues, and are inconsistent with the strictly syntactic search account. These results present a challenge for theories advocating the infallibility of the human parser in the case of reflexive resolution, and provide support for the inclusion of agreement features such as gender in the set of retrieval cues. KW - sentence processing KW - anaphor resolution KW - memory retrieval KW - interference KW - computational modeling KW - eye tracking Y1 - 2016 U6 - https://doi.org/10.3389/fpsyg.2016.00329 SN - 1664-1078 VL - 7 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Vasishth, Shravan A1 - Nicenboim, Bruno T1 - Statistical Methods for Linguistic Research: Foundational Ideas - Part I JF - Language and linguistics compass N2 - We present the fundamental ideas underlying statistical hypothesis testing using the frequentist framework. We start with a simple example that builds up the one-sample t-test from the beginning, explaining important concepts such as the sampling distribution of the sample mean, and the iid assumption. Then, we examine the meaning of the p-value in detail and discuss several important misconceptions about what a p-value does and does not tell us. This leads to a discussion of Type I, II error and power, and Type S and M error. An important conclusion from this discussion is that one should aim to carry out appropriately powered studies. Next, we discuss two common issues that we have encountered in psycholinguistics and linguistics: running experiments until significance is reached and the ‘garden-of-forking-paths’ problem discussed by Gelman and others. The best way to use frequentist methods is to run appropriately powered studies, check model assumptions, clearly separate exploratory data analysis from planned comparisons decided upon before the study was run, and always attempt to replicate results. Y1 - 2016 U6 - https://doi.org/10.1111/lnc3.12201 SN - 1749-818X VL - 10 SP - 349 EP - 369 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Paape, Dario A1 - Vasishth, Shravan T1 - Local Coherence and Preemptive Digging-in Effects in German JF - Language and speech N2 - SOPARSE predicts so-called local coherence effects: locally plausible but globally impossible parses of substrings can exert a distracting influence during sentence processing. Additionally, it predicts digging-in effects: the longer the parser stays committed to a particular analysis, the harder it becomes to inhibit that analysis. We investigated the interaction of these two predictions using German sentences. Results from a self-paced reading study show that the processing difficulty caused by a local coherence can be reduced by first allowing the globally correct parse to become entrenched, which supports SOPARSE’s assumptions. KW - Local coherence KW - digging-in effects KW - self-paced reading KW - SOPARSE KW - sentence processing KW - German Y1 - 2016 U6 - https://doi.org/10.1177/0023830915608410 SN - 0023-8309 SN - 1756-6053 VL - 59 SP - 387 EP - 403 PB - Sage Publ. CY - London ER - TY - JOUR A1 - Nicenboim, Bruno A1 - Vasishth, Shravan T1 - Statistical methods for linguistic research: Foundational Ideas-Part II JF - Language and linguistics compass N2 - We provide an introductory review of Bayesian data analytical methods, with a focus on applications for linguistics, psychology, psycholinguistics, and cognitive science. The empirically oriented researcher will benefit from making Bayesian methods part of their statistical toolkit due to the many advantages of this framework, among them easier interpretation of results relative to research hypotheses and flexible model specification. We present an informal introduction to the foundational ideas behind Bayesian data analysis, using, as an example, a linear mixed models analysis of data from a typical psycholinguistics experiment. We discuss hypothesis testing using the Bayes factor and model selection using cross-validation. We close with some examples illustrating the flexibility of model specification in the Bayesian framework. Suggestions for further reading are also provided. Y1 - 2016 U6 - https://doi.org/10.1111/lnc3.12207 SN - 1749-818X VL - 10 SP - 591 EP - 613 PB - Wiley-Blackwell CY - Hoboken ER -