Does morphological complexity affect word segmentation? Evidence from computational modeling

How can infants detect where words or morphemes start and end in the continuous stream of speech? Previous computational studies have investigated this question mainly for English, where morpheme and word boundaries are often isomorphic. Yet in many languages, words are often multimorphemic, such that word and morpheme boundaries do not align. Our study employed corpora of two languages that differ in the complexity of inflectional morphology, Chintang (Sino-Tibetan) and Japanese (in Experiment 1), as well as corpora of artificial languages ranging in morphological complexity, as measured by the ratio and distribution of morphemes per word (in Experiments 2 and 3). We used two baselines and three conceptually diverse word segmentation algorithms, two of which rely purely on sublexical information using distributional cues, and one that builds a lexicon. The algorithms’ performance was evaluated on both word- and morpheme-level representations of the corpora.Segmentation results were better for the morphologically simpler languages than for the morphologically more complex languages, in line with the hypothesis that languages with greater inflectional complexity could be more difficult to segment into words. We further show that the effect of morphological complexity is relatively small, compared to that of algorithm and evaluation level. We therefore recommend that infant researchers look for signatures of the different segmentation algorithms and strategies, before looking for differences in infant segmentation landmarks across languages varying in complexity.

Distributional learning of recursive structures

Languages differ regarding the depth, structure, and syntactic domains of recursive structures. Even within a single language, some structures allow infinite self-embedding while others are more restricted. For example, English allows infinite free embedding of the prenominal genitive -s, whereas the postnominal genitive of is largely restricted to only one level and to a limited set of items. Therefore, while the ability for recursion is considered as a crucial part of the language faculty, speakers need to learn from experience which specific structures allow free embedding and which do not. One effort to account for the mechanism that underlies this learning process, the distributional learning proposal, suggests that the recursion of a structure (e.g. X1’s-X2) is licensed if the X1 position and the X2 position are productively substitutable in the input. A series of corpus studies have confirmed the availability of such distributional cues in child directed speech. The present study further tests the distributional learning proposal with an artificial language learning experiment. We found that, as predicted, participants exposed to productive input were more likely to accept unattested strings at both one and two-embedding levels than participants exposed to unproductive input. Therefore, our results suggest that speakers can indeed use distributional information at one level to learn whether or not a structure is freely recursive.

The role of indexical cues in the distributional learning of phonetic categories.

Theories of the distributional learning of phonetic categories assume that input provides reliable distributional cues for the categorization of speech sounds. In the real world, however, not all talkers produce exactly the same distributions of speech sounds, and the talker-dependent variation may undermine the reliability of the distributional cues. In this study, we investigated how learners might overcome talker-dependent variation. Specifically, we tested whether adults can learn two phonetic categories from input in which talker-dependent variation introduces potential ambiguities into the categorization of speech sounds. The results suggest that they can overcome this kind of ambiguity by using indexical information (i.e., the identity of talkers).

Are you what you read? Predicting implicit attitudes to immigration based on linguistic distributional cues from newspaper readership; a pre-registered study

The implicit association test (IAT) measures bias towards often controversial topics (e.g., race, religion), while newspapers typically take strong positive/negative stances on such issues. In a pre-registered study, we developed and administered an immigration IAT to readers of the Daily Mail (a typically anti-immigration publication) and the Guardian (typically pro-immigration publication) newspapers. IAT materials were constructed based on co-occurrence frequencies from each newspapers' website for immigration-related terms (migrant/immigrant) and positive/negative attributes (skilled/unskilled). Target stimuli showed stronger negative associations with immigration concepts in the Daily Mail compared to the Guardian, and stronger positive associations in the Guardian corpus compared to the Daily Mail corpus. Consistent with these linguistic distributional differences, Daily Mail readers exhibited a larger IAT bias, revealing stronger negative associations to immigration concepts compared to Guardian readers. This difference in overall bias was not fully explained by other variables, and raises the possibility that exposure to biased language contributes to biased implicit attitudes.

Syntactic Cues Take Precedence Over Distributional Cues in Native and Non-Native Speech Segmentation

This study investigates whether syntactic cues take precedence over distributional cues in native and non-native speech segmentation by examining native and non-native speech segmentation in potential French-liaison contexts. Native French listeners and English-speaking second-language learners of French completed a visual-world eye-tracking experiment. Half the stimuli contained the pivotal consonant /t/, a frequent word onset but infrequent liaison consonant, and half contained /z/, a frequent liaison consonant but rare word onset. In the adjective–noun condition (permitting liaison), participants heard a consonant-initial target (e.g., le petit tatoué; le fameux zélé) that was temporarily ambiguous at the segmental level with a vowel-initial competitor (e.g., le petit [t]athée; le fameux [z]élu); in the noun–adjective condition (not permitting liaison), they heard a consonant-initial target (e.g., le client tatoué; le Français zélé) that was not temporarily ambiguous with a vowel-initial competitor (e.g., le client [*t]athée; le Français [*z]élu). Growth-curve analyses revealed that syntactic context modulated both groups’ fixations (noun–adjective > adjective–noun), and pivotal consonant modulated both groups’ fixations (/t/ > /z/) only in the adjective–noun condition, with the effect of the consonant decreasing in more proficient French learners. These results suggest that syntactic cues override distributional cues in the segmentation of French words in potential liaison contexts.

Flexible perceptual sensitivity to acoustic and distributional cues

Pronunciation variation in many ways is systematic, yielding patterns that a canny listener can exploit in order to aid perception. This work asks whether listeners actually do draw upon these patterns during speech perception. We focus in particular on a phenomenon known as paradigmatic enhancement, in which suffixes are phonetically enhanced in verbs which are frequent in their inflectional paradigms. In a set of four experiments, we found that listeners do not seem to attend to paradigmatic enhancement patterns. They do, however, attend to the distributional properties of a verb’s inflectional paradigm when the experimental task encourages attention to sublexical detail, as is the case with phoneme monitoring (Experiment 1a–b). When tasks require more holistic lexical processing, as with lexical decision (Experiment 2), the effect of paradigmatic probability disappears. If stimuli are presented in full sentences, such that the surrounding context provides richer contextual and semantic information (Experiment 3), even otherwise robust influences like lexical frequency disappear. We propose that these findings are consistent with a perceptual system that is flexible, and devotes processing resources to exploiting only those patterns that provide a sufficient cognitive return on investment.

In-lab Replication of Saffran, Newport, & Aslin (1996) Word segmentation:The role of distributional cues, Exp. 1

These are the results for an in-lab replication of Saffran, Newport, & Aslin (1996) Word segmentation: The role of distributional cues, Journal of Memory and Language, 35, 606-621. This replication follows an online replication of the same experiment (Hartshorne 2017, Replication of Saffran, Newport, & Aslin (1996) Word segmentation: The role of distributional cues, Exp. 1. PsyArXiv doi:10.17605/OSF.IO/E5C64).