Characterising language learning in typical and atypical populations

Young children learn words rapidly and amongst substantial environmental variation. How they manage to do so, and with relatively consistent results, is the topic of much debate in the developmental literature. Recent research has turned to the environmental variation surrounding children, and the vital information it may hold to help children to learn words more efficiently by way of statistical learning. The responsiveness of caregivers to this variation however – and the subsequent effects of the cues that they provide in real time – remains under-investigated. The first part of this thesis investigates two key questions: 1) do caregivers alter the cues they provide in response to variation in the environment during word learning, and 2) does both environmental variation and caregiver response affect how their children learn words? The results of Study 1 demonstrate not only that caregiver cue use is dependent upon the amount of variation present, but also that children can learn more effectively in the face of variation. Study 2 then explores how these cues affect learning in real time, addressing the following questions: 1) how do adult learners make use of visual cues in relation to auditory labels as the learning process unfolds temporally, and 2) does interfering with this process affect word learning? This second study shows that it matters most when such cues occur in relation to the given label as the word learning process unfolds in time. These studies use a multi-disciplinary approach (computational modelling, child and adult experimental studies, and eyetracking) to address the multi-factorial process of language acquisition, and show how investigating the interaction of cues with environmental variation and within-trial learning processes can help us understand how children manage to learn words so consistently. The multi-factorial process of word learning is then further explored through the lens of atypical language development, and offers a longitudinal perspective of word learning. Whereas part 1 of the thesis addresses receptive ability in cross-sectional studies, part 2 addresses the additional effects that expressive ability have on word learning processes over time. Late talkers are children who are developing typically with the exception of significant expressive language delay, producing fewer words than approximately 90% of their peers. Their unique deficit offers the chance to elucidate the differences between receptive and expressive language, and to study how language scaffolds development in other domains, such as symbolic understanding of pictures. However, late talking is also problematic: it is a risk factor for Developmental Language Delay, yet late talking children are notoriously heterogenous as a group, making predicting outcomes difficult. Crucially, determining whether or not late talking children utilise word learning mechanisms differently to typically developing children can provide an evidence-base for predicting outcomes from a clinical perspective. The second part of this thesis reports a longitudinal study over 2 years in a cohort of late talking and typically developing children. Two research questions are examined: 1) do late talkers show deficits in word learning mechanisms as compared to typically developing children? 2) do late talking children show an impaired understanding of pictorial symbols as a result of their language delay, and how does expressive language affect symbolic understanding more generally? This longitudinal study is unique in that it takes into account individual variation within the sample, and it also provides further evidence that a multiple hit hypothesis may best reflect the data, where a deficit in one area of ability does not necessarily lead to poor outcomes unless further deficits in other areas are present (i.e. there are multiple hits to language development ability). Study 3 shows that late talking children are impaired in some, but not all, word learning mechanisms; even when late talking children reach typical expressive vocabulary levels, their phonological abilities still lag behind those of their peers and they may struggle to retain statistical information, although certain key receptive abilities remain intact. Study 4 reports that although late talking children show deficits in symbolic understanding of pictures, their development in this domain follows a delayed trajectory, rather than one that is functionally different to typically developing children. The results also indicate that expressive and receptive language skills differentially support symbolic understanding of pictures, mediated by individual variation in social ability. By examining language acquisition through typical and atypical development, this thesis aims to not only advance understanding of word learning as a process that inevitably involves, and makes use of, variation that exists in a child’s environment, but also examines how expressive language ability – arguably the most clearly observable outcome of word learning for caregivers and early years professionals – interacts with how children come to understand the world around them

Caregivers use gesture contingently to support word learning

Children learn words in environments where there is considerable variability, both in terms of the number of possible referents for novel words, and the availability of cues to support word-referent mappings. How caregivers adapt their gestural cues to referential uncertainty has not yet been explored. We tested a computational model of cross-situational word learning that examined the value of a variable gesture cue during training across conditions of varying referential uncertainty. We found that gesture had a greater benefit for referential uncertainty, but unexpectedly also found that learning was best when there was variability in both the environment (number of referents) and gestural cue use. We demonstrated that these results are reflected behaviourally in an experimental word learning study involving children aged 18-24-month-olds and their caregivers. Under similar conditions to the computational model, caregivers not only used gesture more when there were more potential referents for novel words, but children also learned best when there was some referential ambiguity for words. Thus, caregivers are sensitive to referential uncertainty in the environment and adapt their gestures accordingly, and children are able to respond to environmental variability to learn more robustly. These results imply that training under variable circumstances may actually benefit learning, rather than hinder it

Environmental effects on parental gesture and infant word learning

How infants determine correct word-referent pairings within complex environments is not yet fully understood. The combination of multiple cues, including gestures, may guide learning as part of a communicative exchange between parent and child. Gesture use and word learning are interlinked, with early child gesture predicting later vocabulary size, and parental gesture predicting child gesture. However, the extent to which parents alter gesture cues during word learning according to referential uncertainty is not known. In this study, we manipulated the number of potential referents across conditions during a word learning task with 18–24-month-olds, and explored how changes in parental gesture use translated into infant word learning. We demonstrate that parents alter their gesture use according to the presence, but not the degree, of referential uncertainty. We further demonstrate that a degree of variability in the number of potential referents appears to benefit word learning

Better early than late : The temporal dynamics of pointing cues during cross-situational word learning

Learning the meaning of a word is a difficult task due to the variety of possible referents present in the environment. Visual cues such as gestures frequently accompany speech, and have the potential to reduce referential uncertainty and promote learning, but the dynamics of pointing cues and speech integration are not yet known. If word learning is influenced by when, as well as whether, a learner is directed correctly to a target, then this would suggest temporal integration of visual and speech information can affect the strength of association of word-referent mappings. Across two pre-registered studies, we tested the conditions under which pointing cues promote learning. In a cross-situational word learning paradigm, we showed that the benefit of a pointing cue was greatest when the cue preceded the speech label, rather than following the label (Study 1). In an eye-tracking study (Study 2) the early cue advantage was due to participants’ attention being directed to the referent during label utterance, and this advantage was apparent even at initial exposures of word-referent pairs. Pointing cues promote time-coupled integration of visual and auditory information that aids encoding of word-referent pairs, demonstrating the cognitive benefits of pointing cues occurring prior to speech

Disentangling genetic and environmental influences on early language development: The interplay of genetic propensity for negative emotionality and surgency, and parenting behavior effects on early language skills in an adoption study

Parenting and children's temperament are important influences on language development. However, temperament may reflect prior parenting, and parenting effects may reflect genes common to parents and children. In 561 U.S. adoptees (57% male) and their birth and rearing parents (70% and 92% White, 13% and 4% African American, and 7% and 2% Latinx, respectively), this study demonstrated how genetic propensity for temperament affects language development, and how this relates to parenting. Genetic propensity for negative emotionality inversely predicted language at 27 months (β = −.15) and evoked greater maternal warmth (β = .12), whereas propensity for surgency positively predicted language at 4.5 years (β = .20), especially when warmth was low. Parental warmth (β = .15) and sensitivity (β = .19) further contributed to language development, controlling for common gene effects

Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe

We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median $z\sim 0.03$). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between $z\sim 0.6$ and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July

Sloan Digital Sky Survey IV: mapping the Milky Way, nearby galaxies, and the distant universe

We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median ). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July

Sloan Digital Sky Survey IV : mapping the Milky Way, nearby galaxies, and the distant universe

We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median z ~ 0.03). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between z ~ 0.6 and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July

Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe

We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and high signal-to-noise ratio in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially-resolved spectroscopy for thousands of nearby galaxies (median redshift of z = 0.03). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between redshifts z = 0.6 and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGN and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5-meter Sloan Foundation Telescope at Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5-meter du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in July 2016

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection