Cross-situational word learning in two foreign languages : effects of native language and perceptual difficulty

Cross-situational word learning (CSWL) paradigms have gained traction in recent years as a way to examine word learning in ambiguous scenarios in infancy, childhood, and adulthood. However, no study thus far has examined how CSWL paradigms may provide viable learning pathways for second language (L2) word learning. Here, we used a CSWL paradigm to examine how native Australian English (AusE) speakers learned novel Dutch (Experiment 1) and Brazilian Portuguese (Experiment 2) word-object pairings. During each learning phase trial, two words and objects were presented without indication as to which auditory word belonged to which visual referent. The two auditory words formed a non-minimal or vowel minimal pair. Minimal pairs were classified as "perceptually easy"or "perceptually difficult"based on the acoustic-phonetic relationship between AusE and each L2. At test, participants again saw two visual referents but heard one auditory label and were asked to select the corresponding referent. We predicted that accuracy would be highest for non-minimal pair trials (in which the auditory words associated with the target and distractor object formed a non-minimal pair), followed by perceptually easy minimal pairs, with lowest accuracy for perceptually difficult minimal pair trials. Our results support these hypotheses: While accuracy was above chance for all pair types, in both experiments accuracy was highest for non-minimal pair trials, followed by perceptually easy and then perceptually difficult minimal pair trials. These results are the first to demonstrate the effectiveness of CSWL in adult L2 word learning. Furthermore, the difference between perceptually easy and perceptually difficult minimal pairs in both language groups suggests that the acoustic-phonetic relationship between the L1-L2 is an important factor in novel L2 word learning in ambiguous learning scenarios. We discuss the implications of our findings for L2 acquisition, cross-situational learning and encoding of phonetic detail in a foreign language

Explaining L2 lexical learning in multiple scenarios : cross-situational word learning in L1 Mandarin L2 English speakers

Adults commonly struggle with perceiving and recognizing the sounds and words of a second language (L2), especially when the L2 sounds do not have a counterpart in the learner’s first language (L1). We examined how L1 Mandarin L2 English speakers learned pseudo English words within a cross‐situational word learning (CSWL) task previously presented to monolingual English and bilingual Mandarin‐English speakers. CSWL is ambiguous because participants are not provided with direct mappings of words and object referents. Rather, learners discern word‐object correspondences through tracking multiple co‐occurrences across learning trials. The monolinguals and bilinguals tested in previous studies showed lower performance for pseudo words that formed vowel minimal pairs (e.g., /dit/‐/dɪt/) than pseudo word which formed consonant minimal pairs (e.g., /bɔn/‐/pɔn/) or non‐minimal pairs which differed in all segments (e.g., /bɔn/‐/dit/). In contrast, L1 Mandarin L2 English listeners struggled to learn all word pairs. We explain this seemingly contradicting finding by considering the multiplicity of acoustic cues in the stimuli presented to all participant groups. Stimuli were produced in infant‐directed‐speech (IDS) in order to compare performance by children and adults and because previous research had shown that IDS enhances L1 and L2 acquisition. We propose that the suprasegmental pitch variation in the vowels typical of IDS stimuli might be perceived as lexical tone distinctions for tonal language speakers who cannot fully inhibit their L1 activation, resulting in high lexical competition and diminished learning during an ambiguous word learning task. Our results are in line with the Second Language Linguistic Perception (L2LP) model which proposes that fine‐grained acoustic information from multiple sources and the ability to switch between language modes affects non‐native phonetic and lexical development

Word learning in the field : adapting a laboratory-based task for testing in remote Papua New Guinea

Adapting laboratory psycholinguistic methods to fieldwork contexts can be fraught with difficulties. However, successful implementation of such methods in the field enhances our ability to learn the true extent and limitations of human behavior. This paper reports two attempts to run word learning experiments with the small community of Nungon speakers in Towet village in the Saruwaged Mountains, Papua New Guinea. A first attempt involved running a cross-situational task in which word-object pairings were presented ambiguously in each trial, and an explicit word learning task in which pairings were presented explicitly, or unambiguously, in each trial. While this quickly garnered a respectable 34 participants over the course of a week, it yielded null results, with many participants appearing to show simple patterned responses at test. We interpreted the null result as possibly reflecting the unfamiliarity of both the task and the laptop-based presentation mode. In Experiment 2, we made several adjustments to the explicit word learning task in an attempt to provide clearer instructions, reduce cognitive load, and frame the study within a real-world context. During a second 11-day stay in the village, 34 participants completed this modified task and demonstrated clear evidence of word learning. With this success serving as a future guide for researchers, our experiences show that it may require multiple attempts, even by experienced fieldworkers familiar with the target community, to successfully adapt experiments to a field setting

Resilience of English vowel perception across regional accent variation

In two categorization experiments using phonotactically legal nonce words, we tested Australian English listeners’ perception of all vowels in their own accent as well as in four less familiar regional varieties of English which differ in how their vowel realizations diverge from Australian English: London, Yorkshire, Newcastle (UK), and New Zealand. Results of Experiment 1 indicated that amongst the vowel differences described in sociophonetic studies and attested in our stimulus materials, only a small subset caused greater perceptual difficulty for Australian listeners than for the corresponding Australian English vowels. We discuss this perceptual tolerance for vowel variation in terms of how perceptual assimilation of phonetic details into abstract vowel categories may contribute to recognizing words across variable pronunciations. Experiment 2 determined whether short-term multi-talker exposure would facilitate accent adaptation, particularly for those vowels that proved more difficult to categorize in Experiment 1. For each accent separately, participants listened to a pre-test passage in the nonce word accent but told by novel talkers before completing the same task as in Experiment 1. In contrast to previous studies showing rapid adaptation to talker-specific variation, our listeners’ subsequent vowel assimilations were largely unaffected by exposure to other talkers’ accent-specific variation

Revealing perceptual structure through input variation: cross-accent categorization of vowels in five accents of English

This paper characterizes the perceptual structure of vowel systems in five regional accents of English, from Australia (A), New Zealand (Z), London (L), Yorkshire (Y), and Newcastle upon Tyne (N), on the basis of “whole system” vowel categorization experiments. We established patterns of within-accent vowel confusions, and then explored cross-accent perception, assessing how listeners from one accent background categorize vowels from another. Our experimental task required mapping continuous phonetic dimensions to perceptual categories in the absence of phonotactic and lexical cues to vowel identity and socio-indexical information about the talker. Our results show that, without these sources of information, there is uncertainty in vowel categorization, even for native accent vowels, and that this degree of uncertainty increases for unfamiliar accents. The patterns of cross-accent perception largely reflect the accent-specific perceptual structure of the listener, as opposed to adaptations to the stimulus accents. This finding contrasts with the type of active talker adaptation found with tasks offering lexical information about vowel identity and indexical information about the talker

Development of phonologically specified word forms

Word segmentation is qualitatively different between infants and adults, occurring in tandem with word recognition in adults, with words segmented as they are recognized from the speech stream. This requires a lexicon consisting of most commonly occurring words, which infants lack. Thus, infants are faced with the problem of needing to segment words to add them to the lexicon, but not having a lexicon large enough to segment words online as adults do. Thus, early word segmentation occurs separately from word recognition. Infants segment words primarily by attending to the predominant metrical patterns in their language as cues to likely word boundaries, and can then learn the segmental patterns within those boundaries. In adults, attention to metrical patterns is a supplementary cue, and thus word segmentation by adults is robust to suprasegmental variation that can alter metrical patterns, such as that across foreign-accented speech. Word recognition is also qualitatively different between young children and adults. Early word forms are comprised of strict phonetic patterns based on experienced pronunciations that are intolerant to previously unexperienced variation. However, mature word forms are phonologically specified, comprised of the higher-order phonological form of the word above the level of phonemic variation. This allows a robustness to considerable segmental variation, even variation that violates native phonemic boundaries, as can occur across regional accents. Adults are generally able to recognize cross-accent pronunciations via their grasp of when variation does not change a word's underlying phonological form. This thesis explores when these qualitative differences between immature and mature word segmentation and recognition begin to be resolved by young children

Modeling a direct role of vocabulary size in driving cross-accent word identification

Children typically do not spontaneously recognize accented productions of known words until approximately 19 months. In 15-month-olds, however, this ability is correlated with vocabulary size. Vocabulary size may support cross-accent accommodation by decreasing the likelihood that a variant production is considered to be an unknown word. We simulated a cross-accent word identification experiment, with word tokens generated from a two-dimensional Gaussian space, and accented productions simulated via linear transforms. Simulated participants were Bayesian classifiers with large or small vocabularies. Our large vocabulary group accurately classified more accented tokens and were less likely to classify an accented token as an unknown word. Thus, one way a growing vocabulary size may foster cross-accent accommodation is through increasing infants’ propensity to fit accented variants to known words, rather than treating them as unknown words

Modeling a direct role of vocabulary size in driving cross-accent word identification

Children typically do not spontaneously recognize accented productions of known words until approximately 19 months. In 15-month-olds, however, this ability is correlated with vocabulary size. Vocabulary size may support cross-accent accommodation by decreasing the likelihood that a variant production is considered to be an unknown word. We simulated a cross-accent word identification experiment, with word tokens generated from a two-dimensional Gaussian space, and accented productions simulated via linear transforms. Simulated participants were Bayesian classifiers with large or small vocabularies. Our large vocabulary group accurately classified more accented tokens and were less likely to classify an accented token as an unknown word. Thus, one way a growing vocabulary size may foster cross-accent accommodation is through increasing infants’ propensity to fit accented variants to known words, rather than treating them as unknown words

Explaining L2 Lexical Learning in Multiple Scenarios : Cross-Situational Word Learning in L1 Mandarin L2 English Speakers

Adults commonly struggle with perceiving and recognizing the sounds and words of a second language (L2), especially when the L2 sounds do not have a counterpart in the learner’s first language (L1). We examined how L1 Mandarin L2 English speakers learned pseudo English words within a cross-situational word learning (CSWL) task previously presented to monolingual English and bilingual Mandarin-English speakers. CSWL is ambiguous because participants are not provided with direct mappings of words and object referents. Rather, learners discern word-object correspondences through tracking multiple co-occurrences across learning trials. The monolinguals and bilinguals tested in previous studies showed lower performance for pseudo words that formed vowel minimal pairs (e.g., /dit/-/dɪt/) than pseudo word which formed consonant minimal pairs (e.g., /bɔn/-/pɔn/) or non-minimal pairs which differed in all segments (e.g., /bɔn/-/dit/). In contrast, L1 Mandarin L2 English listeners struggled to learn all word pairs. We explain this seemingly contradicting finding by considering the multiplicity of acoustic cues in the stimuli presented to all participant groups. Stimuli were produced in infant-directed-speech (IDS) in order to compare performance by children and adults and because previous research had shown that IDS enhances L1 and L2 acquisition. We propose that the suprasegmental pitch variation in the vowels typical of IDS stimuli might be perceived as lexical tone distinctions for tonal language speakers who cannot fully inhibit their L1 activation, resulting in high lexical competition and diminished learning during an ambiguous word learning task. Our results are in line with the Second Language Linguistic Perception (L2LP) model which proposes that fine-grained acoustic information from multiple sources and the ability to switch between language modes affects non-native phonetic and lexical development.publishe

Cross-situational learning of minimal word pairs

Cross-situational statistical learning of words involves tracking co-occurrences of auditory words and objects across time to infer word-referent mappings. Previous research has demonstrated that learners can infer referents across sets of very phonologically distinct words (e.g., WUG, DAX), but it remains unknown whether learners can encode fine phonological differences during cross-situational statistical learning. This study examined learners’ cross-situational statistical learning of minimal pairs that differed on one consonant segment (e.g., BON–TON), minimal pairs that differed on one vowel segment (e.g., DEET–DIT), and non-minimal pairs that differed on two or three segments (e.g., BON–DEET). Learners performed above chance for all pairs, but performed worse on vowel minimal pairs than on consonant minimal pairs or non-minimal pairs. These findings demonstrate that learners can encode fine phonetic detail while tracking word-referent co-occurrence probabilities, but they suggest that phonological encoding may be weaker for vowels than for consonants