Coarticulation and learnability of transparent vowels in vowel harmony

The representations of transparent vowels in vowel harmony have been of interest to phonologists because of the challenges they pose for constraints on locality and complexity. One proposal is that transparent vowels in back vowel harmony may be intermediate between front and back. The present study uses two artificial language learning experiments to explore the psychological reality of acoustic differences in transparent vowels in back vs. front vowel contexts. Participants were exposed to a back/round vowel harmony language with a neutral vowel that was spliced so that the F2 was lower in back vowel contexts and higher in front vowel contexts (the Natural condition) or the reverse (the Unnatural condition). While only participants in the Natural condition of Experiment 1 were able to learn the behavior of the transparent vowel relative to a No-Training control, there was no difference between the Natural and Unnatural conditions. In Experiment 2, only participants in the Natural condition learned the vowel harmony pattern, though there were no significant differences between the two conditions. No condition successfully learned the behavior of the transparent vowel in Experiment 2. These results suggest that the effects of small differences in the F2 value of transparent back vowels on learnability are minimal

Modeling harmony biases in learning exceptions to vowel harmony

Artificial language learning experiments typically show non-categorical results after training on categorical data. This is generally due to incomplete learning, but these results can also reveal biases. One example is that participants trained on a vowel harmony language with alternating and non-alternating affixes prefer the non-alternating affix in harmonic contexts (Finley 2021). In this paper, I show that (i) the preference for harmonic items in non-alternating affixes replicates for remote (online) data collection, and (ii) that this effect can be modeled with MaxEnt Harmonic Grammar. In Harmonic Grammar, the harmony score of each candidate determines its grammaticality, and the probability of surfacing. Because non-alternating affixes that satisfy vowel harmony have higher harmony scores than non-alternating affixes that violate harmony, harmonic candidates will be more likely to surface than disharmonic candidates, even when both types of items surface at levels greater than expected by chance. The theoretical and methodological implications for these results are discusse

The Role of Negative and Positive Evidence in Adult Phonological Learning

One of the great mysteries of language development is how children acquire language so efficiently while adults are never able to reach the same level of proficiency. Adding to this mystery is that child learners rarely receive negative evidence regarding the nature of the grammatical structure of their language, but adults are more likely to receive and use such evidence (in classes, corrections, etc.) (Baker, 1979). The present study tests the role of negative evidence in adult language learners, who were exposed to an artificial grammar characterized by round vowel harmony, a phonological process whereby vowels agree in the feature round. Participants were exposed to either positive evidence only (Positive Evidence Condition), or both negative and positive evidence (Positive Evidence Condition). In two experiments, participants in the Positive Evidence Condition outperformed participants in the Negative Evidence Condition, specifically for test items tat measured extension of learned items to novel items. These results suggest that negative evidence may hinder adult grammatical rule learning

Directionality Effects and Exceptions in Learning Phonological Alternations

The present study explores learning vowel harmony with exceptions using the artificial language learning paradigm. Participants were exposed to a back/round vowel harmony pattern in which one affix (either prefix or suffix, depending on the condition) alternated between /me/ and /mo/ depending on the phonetic feature of the stem vowels. In Experiment 1, participants were able to learn the behaviors of both alternating and non-alternating affixes, but were more likely to generalize to novel affixes for non-alternating items than alternating items. In Experiment 2, participants were exposed to training data that contained non-alternating affixes in prefix position while alternating affixes were all suffixes, or vice versa. Participants were able to extend the non-alternating affixes to the novel direction, suggesting that participants inferred a non-directional harmony pattern. Overall, the patterns of alternating affixes are harder to learn than patterns of exceptions that do not alternate, which aligns with previous findings supporting a non-alternation bias. Our study raises the question of how biases towards exceptionality and directionality interact in phonological learning

Lest the Taps Run Dry: Urban Infrastructure, Water Demands and Drought

Hydrologically-driven urban water shortage situations (urban droughts) are becoming increasingly widespread under the combined forces of urbanization and global climate change. Canadian cities are not exempted from these worries: though most parts of the country receive abundant rainfall on an annual basis, summer droughts driven by sub-annual periods of low relative precipitation or snowmelt anomalies are commonplace in different parts of the country. In cities where climate-sensitive water use is widespread, summer drought conditions can be accompanied by upward swings in municipal water demands in response to hot, dry weather; this combination of reduced supply and surging demand can increase cities’ vulnerability to urban drought on a range of timescales. The research presented in this thesis seeks to evaluate and quantify the role of water demand dynamics in driving urban drought conditions in Canada. It employs a combination of literature and case study review, conceptual exploration, and quantitative analysis of water demand data collected from 15 Canadian cities to assess the degree to which water demand fluctuations can contribute to urban water shortage threats across the country. The research begins with a conceptual review of urban drought and the endogenous drivers that influence its impacts, finding that the experience of drought in the urban context is uniquely dependent on the response actions of water managers and water users who provide the driving force behind short-term changes in demand intended to mitigate drought impacts within the urban system. Next, the analysis shifts to an evaluation of the role of summer water use bylaws imposed in Canadian cities in mitigating short-term increases in urban water demand during the summer months, revealing that these restrictions have little overall impact on seasonal water demand patterns, though the most stringent formats did show some demand dampening effects during short-term periods of exceptionally hot, dry summer weather. The research program concludes with an in-depth analysis of long-term climate and water demand datasets to detect shifts in urban water demand during summer periods of meteorological drought in Canadian cities. This analysis revealed that summer drought periods are indeed strongly correlated with excess summer water demands, though maximum summer temperatures were more influential than drought condition in most cases. Results from the research presented in this thesis suggest that water demands in Canadian cities tend to surge during summer periods of hot and drought-like conditions, thus aggravating the strained supply:demand relationship that drives urban water shortage threats. While findings confirm that the actions of water managers and water users are highly influential in mitigating urban drought impacts, quantitative data analysis finds no indication that the types of seasonal water restrictions commonly imposed in Canadian cities are effective in reducing climate-driven surges in water demand

Generalization Beyond Similarity: Support for Abstract Phonology

The present paper provides evidence from an artificial grammar learning task that supports abstract representations for phonology. Learners exposed to a novel back/round vowel harmony pattern were able to discriminate between grammatical and ungrammatical items that contained novel affixes, even though participants rated these novel items as highly dissimilar to exposure items. These results suggest that learners do not use exemplar-based notions of similarity as a metric for acceptability, but use abstract notions of grammaticality and markedness

Perceptually Based Constraints and Metathesis: Evidence from Artificial Grammar

The present paper explores the role of sonority and other perceptual constraints in governing syllable structure constraints. One of the most important issues in phonology today is the formalization of the phonetic grounding of markedness constraints (Hayes and Steriade 2004). Sonority constraints have been particularly controversial because there is no formalized definition of sonority, but rather several different contributing factors, such as intensity, constriction and formant transitions, that all vary depending on context (Henke, Kaisse, and Wright 2012; Wright 2004). This paper makes use of an artificial grammar learning paradigm, whereby adult English speakers were exposed to a consonant-consonant metathesis pattern that either improved sonority at a syllable boundary, or worsened sonority at a syllable boundary. Learners did not show generalization in line with sonority-based syllable contact laws, but instead showed generalization in accordance with avoidance of a voiced obstruent in coda position, thus supporting a theory of sonority and syllable contact that makes use of the interaction of perceptual cues, rather than a strict, abstract sonority hierarchy

Using Biofeedback to Reduce Spatiotemporal Asymmetry Impairs Dynamic Balance in People Post-Stroke

Background. People poststroke often walk with a spatiotemporally asymmetric gait, due in part to sensorimotor impairments in the paretic lower extremity. Although reducing asymmetry is a common objective of rehabilitation, the effects of improving symmetry on balance are yet to be determined. Objective. We established the concurrent validity of whole-body angular momentum as a measure of balance, and we determined if reducing step length asymmetry would improve balance by decreasing whole-body angular momentum. Methods. We performed clinical balance assessments and measured wholebody angular momentum during walking using a full-body marker set in a sample of 36 people with chronic stroke. We then used a biofeedback-based approach to modify step length asymmetry in a subset of 15 of these individuals who had marked asymmetry and we measured the resulting changes in whole-body angular momentum. Results. When participants walked without biofeedback, whole-body angular momentum in the sagittal and frontal plane was negatively correlated with scores on the Berg Balance Scale and Functional Gait Assessment supporting the validity of whole-body angular momentum as an objective measure of dynamic balance. We also observed that when participants walked more symmetrically, their wholebody angular momentum in the sagittal plane increased rather than decreased. Conclusions. Voluntary reductions of step length asymmetry in people poststroke resulted in reduced measures of dynamic balance. This is consistent with the idea that after stroke, individuals might have an implicit preference not to deviate from their natural asymmetry while walking because it could compromise their balance. Clinical Trials Number: NCT03916562

Multi-Site Identification and Generalization of Clusters of Walking Behaviors in Individuals With Chronic Stroke and Neurotypical Controls

Background Walking patterns in stroke survivors are highly heterogeneous, which poses a challenge in systematizing treatment prescriptions for walking rehabilitation interventions. Objectives We used bilateral spatiotemporal and force data during walking to create a multi-site research sample to: (1) identify clusters of walking behaviors in people post-stroke and neurotypical controls and (2) determine the generalizability of these walking clusters across different research sites. We hypothesized that participants post-stroke will have different walking impairments resulting in different clusters of walking behaviors, which are also different from control participants. Methods We gathered data from 81 post-stroke participants across 4 research sites and collected data from 31 control participants. Using sparse K-means clustering, we identified walking clusters based on 17 spatiotemporal and force variables. We analyzed the biomechanical features within each cluster to characterize cluster-specific walking behaviors. We also assessed the generalizability of the clusters using a leave-one-out approach. Results We identified 4 stroke clusters: a fast and asymmetric cluster, a moderate speed and asymmetric cluster, a slow cluster with frontal plane force asymmetries, and a slow and symmetric cluster. We also identified a moderate speed and symmetric gait cluster composed of controls and participants post-stroke. The moderate speed and asymmetric stroke cluster did not generalize across sites. Conclusions Although post-stroke walking patterns are heterogenous, these patterns can be systematically classified into distinct clusters based on spatiotemporal and force data. Future interventions could target the key features that characterize each cluster to increase the efficacy of interventions to improve mobility in people post-stroke

The Ninth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-III Baryon Oscillation Spectroscopic Survey

The Sloan Digital Sky Survey III (SDSS-III) presents the first spectroscopic data from the Baryon Oscillation Spectroscopic Survey (BOSS). This ninth data release (DR9) of the SDSS project includes 535,995 new galaxy spectra (median z=0.52), 102,100 new quasar spectra (median z=2.32), and 90,897 new stellar spectra, along with the data presented in previous data releases. These spectra were obtained with the new BOSS spectrograph and were taken between 2009 December and 2011 July. In addition, the stellar parameters pipeline, which determines radial velocities, surface temperatures, surface gravities, and metallicities of stars, has been updated and refined with improvements in temperature estimates for stars with T_eff<5000 K and in metallicity estimates for stars with [Fe/H]>-0.5. DR9 includes new stellar parameters for all stars presented in DR8, including stars from SDSS-I and II, as well as those observed as part of the SDSS-III Sloan Extension for Galactic Understanding and Exploration-2 (SEGUE-2). The astrometry error introduced in the DR8 imaging catalogs has been corrected in the DR9 data products. The next data release for SDSS-III will be in Summer 2013, which will present the first data from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) along with another year of data from BOSS, followed by the final SDSS-III data release in December 2014.Comment: 9 figures; 2 tables. Submitted to ApJS. DR9 is available at http://www.sdss3.org/dr