Is retroflexion a stable cue for distributional learning for speech sounds across languages? Learning for some bilingual adults, but not generalisable to a wider population in a well powered pre-registered study

Abstract

Bilinguals are widely reported to have certain kinds of cognitive advantages, including language learning advantages. One possible pathway is a language-specific transfer effect, whereby sensitivity to structural regularities in known languages can be brought to to-be-acquired languages that share particular features. Here we tested for transfer of a specific linguistic property, sensitivity to retroflexion as contrastive phonemic feature. We designed a task for bilinguals with homogeneous language exposure (i.e., bilingual in the same languages) and heterogeneous feature representation (i.e., differing levels of proficiency). Hindi and Mandarin Chinese both have retroflexion in phoneme contrasts (Hindi: stop consonants, Mandarin: sibilants). In a preregistered study, we conducted a statistical learning task for the Hindi dental-retroflex stop contrast with a group of early parallel English-Mandarin bilinguals, who varied in their Mandarin understanding levels. We based the target sample size on power analysis of a pilot study with a Bayesian stop-rule after minimum threshold. Contrary to the pilot study (N = 15), the main study (N = 50) did not find evidence for a learning effect, nor language-experience variance within the group. This finding suggests that statistical learning effects for the feature in question may be more fragile than commonly assumed, and may be evident in only a small subsample of the general population (as in our pilot). These stimuli have previously shown learning effects in children, so an additional possibility is that neural commitment to adults’ languages prevents learning of the fine-stimulus contrast in question for this adult population.

Is retroflexion a stable cue for distributional learning for speech sounds across languages? Learning for some bilingual adults, but not generalisable to a wider population in a well powered pre-registered study

“…All stimuli were presented on OpenSesame ( Mathôt, Schreij & Theeuwes, 2012 ). Code for the study is archived in the repository for this paper ( Goh, Styles & Onnis, 2020 ).…”

“…To capture variance in participants’ individual language exposure, at the end of the alien message task participants were asked to rate their proficiencies in all of the languages/dialects they understand on a Likert scale from 1, “I understand a few words in this language”, to 7, “I have native-level understanding of this language”. The full demographic and language questions are in the repository for this paper ( Goh, Styles & Onnis, 2020 ).…”

“…The prior of 0.17 was determined using the size of the measured difference between pre- and post-training slope values in the pilot study. The hypotheses and analysis plan were preregistered on the Open Science Framework ( Goh, Styles & Onnis, 2020 ). The procedure was reviewed and approved by the ethics board of the host institution Nanyang Technological University (IRB-2019-01-034).…”