Developing Production Skills through Implicit Learning

Language proficiency largely relies on implicit knowledge, which is unconscious and operates independently of voluntary control. Implicit learning is a process of incidental learning which results in the acquisition of implicit knowledge. We know that adult learners can acquire knowledge of novel L2 linguistic rules through implicit learning, as evidenced by their performance on receptive tasks. However, it is unclear whether implicit learning processes can also support the development of L2 production skills. The central question of this dissertation was whether it would be possible for learners to acquire implicit knowledge of a new rule through implicit learning and use it directly in spoken production. Our second question concerns the relationship between production and comprehension: we asked whether implicit knowledge acquired through a production task would also lead to improved performance in comprehension. To address these questions, we trained participants on a semiartificial language based on a rule naturally found in Czech: specifically, the usage rule for a pair of spatial prepositions (v and na) which alternate depending on the distinction between open and enclosed spaces. Training was carried out using a novel methodology based on elicited oral imitation, which was also used to test productive knowledge. Participants were also tested on comprehension, using both reaction time and recognition memory paradigms. Our findings suggest that it is possible to acquire implicit productive knowledge through a production-based task, and to generalise it to new instances in spoken production. The results of our experiments also show that learning outcomes were sensitive to the specific procedure used to train participants, which appeared to interact with individual differences in working memory. Finally, we found limited evidence that implicit knowledge acquired through production could be transferred to comprehension, supporting a skill-specific account of implicit knowledge

On the formation of propylene oxide from propylene in space: gas-phase reactions

In the present article, we have investigated the possibility of forming propylene oxide (PO) from propylene (PE) by bi-molecular reactions. Propylene oxide is the first chiral molecule observed in the interstellar medium, and studying the thermodynamics and kinetics of formation can suggest possible synthetic routes. We have focused our attention on gas-phase reactions, and the presence of an environment is discussed in particular for the possibility of forming it by association reactions. In particular, we have considered radical and ion–molecule reactions. Results show that the main gas-phase route to PO formation is represented by ion–molecule reactions which turn out to be compatible with astrophysical conditions, notably: PE + O + and PE+HO2+. Their final product is not PO, but its ionized variant PO + that can be neutralized by electron capture. The only thermodynamically and kinetically allowed reaction which can directly lead to neutral PO is a collision of PE with a singlet-excited OH + but two competing reactions (leading to PE + and PO +) are thermodynamically favored and thus more plausible in space

Prediction and error-based learning in L2 processing and acquisition : a conceptual review

There is currently much interest in the role of prediction in language processing, both in L1 and L2. For language acquisition researchers, this has prompted debate on the role that predictive processing may play in both L1 and L2 language learning, if any. In this conceptual review, we explore the role of prediction and prediction error as a potential learning aid. We examine different proposed prediction mechanisms and the empirical evidence for them, alongside the factors constraining prediction for both L1 and L2 speakers. We then review the evidence on the role of prediction in learning languages. We report computational modelling which underpins a number of proposals on the role of prediction in L1 and L2 learning, then lay out the empirical evidence supporting the predictions made by modelling, from research into priming and adaptation. Finally, we point out the limitations of these mechanisms in both L1 and L2 speakers

Expectation Violation Leads to Generalization : The Effect of Prediction Error on the Acquisition of New Syntactic Structures

Prediction error is known to enhance priming effects for familiar syntactic structures; it also strengthens the formation of new declarative memories. Here, we investigate whether violating expectations may aid the acquisition of new abstract syntactic structures, too, by enhancing memory for individual instances which can then form the basis for abstraction. In a cross-situational artificial language learning paradigm, participants were exposed to novel syntactic structures in ways that either violated their expectations (Surprisal group) or that conformed to them (Control group). Results from a delayed post-test show that participants in the Surprisal group developed stronger representations of the structures’ form-meaning mappings and were better able to generalize them to new instances, relative to the Control group

The effect of verb surprisal on the acquisition of second language syntactic structures in adults : An artificial language learning study

Inverse probability adaptation effects (the finding that encountering a verb in an unexpected structure increases long-term priming for that structure) have been observed in both L1 and L2 speakers. However, participants in these studies all had established representations of the syntactic structures to be primed. It therefore remains an open question whether inverse probability adaptation effects could take place with newly encountered L2 structures. In a pre-registered experiment, we exposed participants (n = 84) to an artificial language with active and passive constructions. Training on Day 1 established expectations for specific co-occurrence patterns between verbs and structures. On Day 2, established patterns were violated for the surprisal group (n = 42), but not for the control group (n = 42). We observed no immediate priming effects from exposure to high-surprisal items. On Day 3, however, we observed an effect of input variation on comprehension of verb meaning in an auditory grammaticality judgment task. The surprisal group showed higher accuracy for passive structures in both tasks, suggesting that experiencing variation during learning had promoted the recognition of optionality in the target language

Expectation Violation Enhances the Development of New Abstract Syntactic Representations : Evidence from an Artificial Language Learning Study

Prediction error is known to enhance priming effects for familiar syntactic structures; it also strengthens the formation of new declarative memories. Here, we investigate whether violating expectations may aid the acquisition of new abstract syntactic structures, too, by enhancing memory for individual instances which can then form the basis for abstraction. In a cross-situational artificial language learning paradigm, participants were exposed to novel syntactic structures in ways that either violated their expectations (Surprisal group) or that conformed to them (Control group). First, we established a potential expectation to hear feedback that simply repeated the same structure as that just experienced. We then manipulated feedback so that the Surprisal group unexpectedly heard passive structures in feedback following active sentences, while the Control group only heard passive structures following passive sentences. Delayed post-tests examined participants’ structural knowledge both by means of structure test trials (focusing on the active / passive distinction, with both familiar and novel verbs), and by a grammaticality judgment task. The Surprisal group was significantly more accurate than the Control group on the structure test trials with novel verbs and on the grammaticality judgment task, suggesting participants had developed stronger abstract structural knowledge and were better at generalising it to novel instances. Tentative evidence suggested the Surprisal group was not significantly more likely to become aware of the functional distinction between the two structures

Structural Prediction During Language Comprehension Revealed by Electrophysiology : Evidence from Italian Auxiliaries

Prediction in language comprehension has become a key mechanism in recent psycholinguistic theory, with evidence from lexical prediction as a primary source. Less work has focused on whether comprehenders also make structural predictions above the lexical level. Previous research shows that processing is facilitated for syntactic structures which are predictable based on context; however, there is so far no direct evidence that speakers formulate structural predictions ahead of encountering input. We investigated whether subject noun animacy cues comprehenders to predict different verb phrase (VP) structures, with the incompatibility between a low animacy subject and an Agent interpretation of transitives/unergative VPs predicting a derived (passive/unaccusative) VP structure, using Italian auxiliaries. Native Italian speakers read sentences with subject nouns varying from high to low animacy followed by the auxiliary avereHAVE, which is compatible with underived VPs, or essereBE, which is compatible with derived VPs. The auxiliary avereHAVE elicited greater frontal negativity when preceded by a subject noun with lower animacy. The auxiliary essereBE elicited no differential ERP given subject animacy. We propose that this frontal negativity reflects violation of a structural prediction, with amplitude reflecting the strength of initial commitment or difficulty in revising a predicted structure. Differences between auxiliaries are proposed to follow from the more specific distribution of avereHAVE. We argue that this evidence unambiguously supports a predictive mechanism for phrase-level structure

A Context-Aligned Two Thousand Test : Towards estimating high-frequency French vocabulary knowledge for beginner-to-low intermediate proficiency adolescent learners in England

Vocabulary knowledge strongly predicts second-language reading, listening, writing, and speaking. Yet, few tests have been developed to assess vocabulary knowledge in French. The primary aim of this pilot study was to design and initially validate the Context-Aligned Two Thousand Test (CA-TTT), following open research practices. The CA-TTT is a test of written form–meaning recognition of high-frequency vocabulary aimed at beginner-to-low-intermediate learners of French at the end of their fifth year of secondary education. Using an argument-based validation framework, we drew on classical test theory and Rasch modelling, together with correlations with another vocabulary size test and proficiency measures, to assess the CA-TTT’s internal and external validity. Overall, the CA-TTT showed high internal and external validity. Our study highlighted the decisive role of the curriculum in determining vocabulary knowledge in instructed, low-exposure contexts. We discuss how this might contribute to under- or over-estimations of vocabulary size, depending on the relations between the test and curriculum content. Further research using the tool is openly invited, particularly with lower-proficiency learners in this context. Following further validation, the test could serve as a tool for assessing high-frequency vocabulary knowledge at beginner-to-low-intermediate levels, with due attention paid to alignment with curriculum content

Heterogeneity of Signal Transducer and Activator of Transcription Binding Sites in the Long-Terminal Repeats of Distinct HIV-1 Subtypes

HIV-1 can be subdivided into distinct subtypes; the consequences of such a genomic variability remain largely speculative. The long terminal repeats (LTR) control HIV transcription and reflect the major differences of distinct viral subtypes. Three regions in the HIV-1 subtype B LTR are close matches to the Signal Transducer and Activator of Transcription (STAT) consensus sequence. Here, we show heterogeneity in these putative STAT binding sites among HIV-1 LTR subtypes A through G. Transfection of constitutively activated STAT5 lead to transcriptional activation of HIV-1 expression in 293T cells transfected with a reporter assay driven by HIV-1 LTR subtype B. Constitutively activated STAT5 transactivated the LTR of various subtypes in U937 cells with different potency. These findings support and expand the potential relevance of STAT5 activation in HIV infection and may bear relevance for a differential regulation of latency and expression of different subtypes of HIV-1

Increased Bone Marrow Interleukin-7 (IL-7)/IL-7R Levels but Reduced IL-7 Responsiveness in HIV-Positive Patients Lacking CD4+ Gain on Antiviral Therapy

Background: The bone marrow (BM) cytokine milieu might substantially affect T-lymphocyte homeostasis in HIV-positive individuals. Interleukin-7 (IL-7) is a bone marrow-derived cytokine regulating T-cell homeostasis through a CD4+-driven feedback loop. CD4+ T-lymphopenia is associated with increased free IL-7 levels and reduced IL-7R expression/function, which are only partially reverted by highly active antiretroviral therapy (HAART). We investigated the BM production, peripheral expression and signaling (pStat5+ and Bcl-2+ CD4+/CD8+ T cells) of IL-7/IL-7Ra in 30 HAART-treated HIV-positive patients who did not experience CD4+ recovery (CD4+ #200/ml) and who had different levels of HIV viremia; these patients included 18 immunological nonresponders (INRs; HIV-RNA#50), 12 complete failures (CFs; HIV-RNA.1000), and 23 HIVseronegative subjects. Methods: We studied plasma IL-7 levels, IL-7Ra+CD4+/CD8+ T-cell proportions, IL-7Ra mRNA expression in PBMCs, spontaneous IL-7 production by BM mononuclear cells (BMMCs), and IL-7 mRNA/IL-7Ra mRNA in BMMC-derived stromal cells (SCs). We also studied T-cell responsiveness to IL-7 by measuring the proportions of pStat5+ and Bcl-2+ CD4+/CD8+ T cells. Results: Compared to HIV-seronegative controls, CFs and INRs presented elevated plasma IL-7 levels and lower IL-7Ra CD4+/CD8+ cell-surface expression and peripheral blood production, confirming the most relevant IL-7/IL-7R disruption. Interestingly, BM investigation revealed a trend of higher spontaneous IL-7 production in INRs (p = .09 vs. CFs) with a nonsignificant trend toward higher IL-7-Ra mRNA levels in BMMC-derived stromal cells. However, upon IL-7 stimulation, the proportion of pStat5+CD4+ T cells did not increase in INRs despite higher constitutive levels (p = .06); INRs also displayed lower Bcl-2+CD8+ T-cell proportions than controls (p = .04). Conclusions: Despite severe CD4+ T-lymphopenia and a disrupted IL-7/IL-7R profile in the periphery, INRs display elevated BM IL-7/IL-7Ra expression but impaired T-cell responsiveness to IL-7, suggesting the activity of a central compensatory pathway targeted to replenish the CD4+ compartment, which is nevertheless inappropriate to compensate the dysfunctional signaling through IL-7 receptor