Perceptual Assimilation Model Research Articles

Abstraction of phonological representations in adult nonnative speakers

Perception of nonnative contrasts by adult second language (L2) learners is affected by native language phonology. The current study contrasted predictions from two models of L2 phonological acquisition that focus on different representational levels as the origin of native language transfer: the abstract categorization level from the Perceptual Assimilation Model for L2 learners (PAM-L2; Best & Tyler, 2007) and the phonetic level from the Automatic Selective Perception model (ASP; Strange, 2011). The target phonemes were pairs of Arabic consonants that were equally similar on the abstract categorization level but unequally similar on the phonetic level—voiced and voiceless pharyngeal fricatives /ʕ/, /ħ/ and uvular fricatives /χ/, /ʁ/. Twenty intermediate-level English-speaking Arabic L2 learners and 10 Arabic native speakers (NS) completed auditory identification and discrimination tasks. We first conducted a discriminant analysis (DA) to quantify ASP predictions based on phonetic variables. L2 learners were generally more accurate when perceiving the pharyngeal consonants compared to the uvulars and when perceiving the voiced phonemes compared to the voiceless. These findings, and L2 learners’ perceptual variation across contexts, predicted by the DA, suggest that L2 speakers were able to track phonetic cues during L2 perception and thus favor the ASP. These results support the interpretation that L2 learners attend to the phonetic detail in nonnative segments; however, they do not build nativelike phonological representations for the segments with weaker phonetic cues. This ability to process low-level phonetic cues opens the possibility for learners to create more robust phonological representations.

The perceptual assimilation model for suprasegmentals and cross-language lexical-tone identification

We examine how native lexical-tone experience influences identification of novel tone. Cantonese, Thai, Mandarin, and Yoruba listeners identified CV syllables bearing the six phonemic Cantonese tones. Accuracy scores were submitted to a two-way rANOVA with L1-Group (x4) as the between-subjects factor and Tone (x6) as the within-subjects factor. Tone error patterns were also assessed via rANOVAs with L1-Group (x4) as the between-subjects factor and Response-Pattern (% correct versus % other response) as the within-subjects factor. Consistent with previous reports, native listeners’ confusions reflected effects of ongoing tonal mergers and a crowded tone space. Non-native listeners appeared to assimilate novel tones to L1 tone categories by attending to phonetic cues relevant to the phonological and phonetic properties of their L1s. Overall, results support predictions of the Perceptual Assimilation Model for Suprasegmentals (PAM-S). [Support: NSF grant 0965227 to J.A.A.]

Effects of L1 tone on perception of L2 tone - a study of Mandarin tone learning by native Cantonese children

In the present study, the Perceptual Assimilation Model (PAM) was tested on its applicability in child L2 lexical tone acquisition. The possible effect of L1 (Cantonese) lexical tones on L2 (Mandarin) lexical tone learning was explored. Accuracy rate and error patterns were examined with an AX discrimination task and a forced-choice identification task. Forty-nine native Cantonese-speaking students aged 8 years participated in the study. Results revealed that these children exhibited nearly perfect performance in the discrimination of Mandarin tones. However, significant tone differences were detected in the identification task. Tone 4 (T4) was identified with the lowest accuracy, and T1 with the highest. Error analysis revealed that Mandarin T2-T3 was the most confusing pair, followed by the T1-T4 pair. The inherent phonetic similarity between lexical tones in a language and the tone similarities across languages may also have contributed to perception difficulties, which could help to refine and supplement the PAM in the tonal/suprasegmental domain.

Discrimination of Multiple Coronal Stop Contrasts in Wubuy (Australia): A Natural Referent Consonant Account

Native speech perception is generally assumed to be highly efficient and accurate. Very little research has, however, directly examined the limitations of native perception, especially for contrasts that are only minimally differentiated acoustically and articulatorily. Here, we demonstrate that native speech perception may indeed be more difficult than is often assumed, where phonemes are highly similar, and we address the nature and extremes of consonant perception. We present two studies of native and non-native (English) perception of the acoustically and articulatorily similar four-way coronal stop contrast /t ʈ ȶ/ (apico-alveolar, apico-retroflex, lamino-dental, lamino-alveopalatal) of Wubuy, an indigenous language of Australia. The results show that all listeners find contrasts involving /ȶ/ easy to discriminate, but that, for both groups, contrasts involving /t ʈ / are much harder. Where the two groups differ, the results largely reflect native language (Wubuy vs English) attunement as predicted by the Perceptual Assimilation Model [1, 2, 3]. We also observe striking perceptual asymmetries in the native listeners' perception of contrasts involving the latter three stops, likely due to the differences in input frequency. Such asymmetries have not previously been observed in adults, and we propose a novel Natural Referent Consonant Hypothesis to account for the results.

Acoustic Analysis of Persian EFL Learners' Pronunciation of English Vowels

This paper reports the results of an experimental study on non-native production of English vowels. Two groups of Persian EFL learners varying in language proficiency were tested on their ability to produce the nine plain vowels of American English. Vowel production accuracy was assessed by means of acoustic measurements. Ladefoged and Maddison’s (1996) F1 F2 measurements for American English vowel space were used as reference values to be compared with the measurements obtained from the production of Persian EFL learners. The acoustic measurements revealed that learners were not able to control acoustic parameters of vowel quality, even for the more similar vowels in the two languages, in a native-like manner due to interference from their native vowel system. Spectral accuracy measures also did not progress toward more native-like values in the productions of the more proficient learners. Interestingly, the positions achieved for the more dissimilar vowels were neither close to their closest L1 counterparts nor close to their native categories. Interpreting this latter result within the Perceptual Assimilation Model proposed by Best (1994), it could be stated that learners established new phonetic categories for the vowel contrasts that were not used in their native phonological system.

Perception and Production of Thai Learners on English Prepositions

In this paper, Iadopt Best’s (2001) Perceptual Assimilation Model (PAM) to account for how Thai learners acquire English prepositions in prepositional phrases and propose the ranking order of English preposition acquisition into three different categories. The ranking is as follows: Category A is a one-to-one semantic mapping between English and Thai prepositions, therefore ranked first suggesting that they would be the easiest to be acquired. Category B is a one-to-many semantic mapping between English and Thai prepositions. Acquisition of Category B should be more difficult than Category A because one English preposition can have more than one correspondence in Thai. Category C is one-to-null mapping between English and Thai prepositions. A preposition that exists in one language can be null in another language. Category C would rank the lowest in terms of acquisition. The participants consisted of 20 graduate students in the MA program at a university in Bangkok. They were placed into medium (8-10) and low (6-7) proficiency levels of English by a placement test called the Language and Instructor System (ELLIS) administered via computer. The two tests used in this study were a grammatical judgment test for English prepositions and a writing test. The two tests were exactly parallel in each item. The correlation between their awareness in spotting incorrect prepositions and the ability to use correct ones were measured using Pearson’s correlation coefficient. The results were consistent with the ranking proposed here. It showed that L2 Thai acquirers of English prepositions were able to judge grammatical and ungrammatical sentences correctly with respect to the ranking A>>B>>C. However, no significant difference of the correlation between perception and production in all categories was found. The results further revealed that both medium and low proficient participants were able to perceive and produce dependent prepositions more accurately than independent prepositions.

Perceptual assimilation of lexical tone: the roles of language experience and visual information.

Using Best’s (1995) perceptual assimilation model (PAM), we investigated auditory–visual (AV), auditory-only (AO), and visual-only (VO) perception of Thai tones. Mandarin and Cantonese (tone-language) speakers were asked to categorize Thai tones according to their own native tone categories, and Australian English (non-tone-language) speakers to categorize Thai tones into their native intonation categories—for instance, question or statement. As comparisons, Thai participants completed a straightforward identification task, and another Australian English group identified the Thai tones using simple symbols. All of the groups also completed an AX discrimination task. Both the Mandarin and Cantonese groups categorized AO and AV Thai falling tones as their native level tones, and Thai rising tones as their native rising tones, although the Mandarin participants found it easier to categorize Thai level tones than did the Cantonese participants. VO information led to very poor categorization for all groups, and AO and AV information also led to very poor categorizations for the English intonation categorization group. PAM’s predictions regarding tone discriminability based on these category assimilation patterns were borne out for the Mandarin group’s AO and AV discriminations, providing support for the applicability of the PAM to lexical tones. For the Cantonese group, however, PAM was unable to account for one specific discrimination pattern—namely, their relatively good performance on the Thai high–rising contrast in the auditory conditions—and no predictions could be derived for the English groups. A full account of tone assimilation will likely need to incorporate considerations of phonetic, and even acoustic, similarity and overlap between nonnative and native tone categories.

Cross-language identification of non-native lexical tone

We extend to lexical-tone systems a model of second-language perception, the Perceptual Assimilation Model (PAM) (Best & Tyler, 2007), to examine whether native-language lexical-tone experience influences identification of novel tone. Native listeners of Cantonese, Thai, Mandarin, and Yoruba hear six CV syllables, each produced with the three phonemic Yoruba tones (High-level/H, Mid-level/M, Low-level/L), presented randomly three times. In a 3-AFC task, participants indicate a syllable’s tone by selecting from a set of arrows the one that illustrates its pitch trajectory. Accuracy scores (proportion correct) were submitted to a two-way rANOVA with L1-Group (x4) as the between-subjects factor and Tone (x3) as the within-subjects factor. There was no main effect of Tone or Group. The Tone-by-Group interaction was significant (p = 0.031) but driven by one group: Thai listeners identified H and M more accurately than L (both p < 0.05), though L accuracy was above chance (59%; chance = 33.33%). Tone-error patterns indicate that Thai listeners primarily confused L with M (two-way L1-Group x Response-pattern rANOVA p < 0.05). Overall, despite their different tonal-L1 backgrounds, listeners performed comparably. As predicted by the PAM, listeners attended to gradient phonetic detail and acoustic cues relevant to L1 phoneme distinctions (F0 height/direction) in order to classify non-native contrasts. [NSF grant #0965227.]

Korean listeners’ perception of L2 English phoneme contrast

The current study investigates how Korean L2 listeners identify English minimal pairs contrasting in voicing and manner and attempts to testify the essential tenets of the Perceptual Assimilation Model. Another purpose of our research is to explore other factors which might affect the identification patterns within the identical contrast categories proposed by PAM. Identification tasks were performed with target vowel and consonant contrasts within real word and nonce word conditions. Identification accuracy and reaction time were measured to evaluate the relative difficulty of L2 sound identification. First, we found that Korean listeners encountered the most difficulty in identifying L2 English minimal pairs in the Single Category contrast, followed by those in the Category Goodness contrast, and those in the TC contrast were most accurately and rapidly identified in accordance with the predictions of the PAM model. Next, it was shown that there were varying levels of difficulty in identification tasks within the TC and SC contrast. This finding suggests that PAM is not sufficient to predict L2 identification accuracy and other factors should be taken into consideration, including the Speech Learning Model, and other phonological factors such as manner of articulation, the vocalicity of the segments, individual contrast type, etc.

Perceptual Assimilation and Discrimination of Non-Native Vowel Contrasts

Research on language-specific tuning in speech perception has focused mainly on consonants, while that on non-native vowel perception has failed to address whether the same principles apply. Therefore, non-native vowel perception was investigated here in light of relevant theoretical models: the Perceptual Assimilation Model (PAM) and the Natural Referent Vowel (NRV) framework. American-English speakers completed discrimination and native language assimilation (categorization and goodness rating) tests on six nonnative vowel contrasts. Discrimination was consistent with PAM assimilation types, but asymmetries predicted by NRV were only observed for single-category assimilations, suggesting that perceptual assimilation might modulate the effects of vowel peripherality on non-native vowel perception. © 2014 S. Karger AG, Basel

PHONETIC INFLUENCES ON ENGLISH AND FRENCH LISTENERS’ ASSIMILATION OF MANDARIN TONES TO NATIVE PROSODIC CATEGORIES

This study examined how native speakers of Australian English and French, nontone languages with different lexical stress properties, perceived Mandarin tones in a sentence environment according to their native sentence intonation categories (i-Categories) in connected speech. Results showed that both English and French speakers categorized Mandarin tones primarily on the phonetic similarities of the pitch contours between the Mandarin tones and their native i-Categories. Moreover, French but not English speakers were able to detect the fine-detailed phonetic differences between Tone 3 (T3) and Tone 4 (T4; i.e., low or low-falling tone vs. high-falling tone), which suggests that the stress differences between these languages may affect nonnative tone perception: English uses lexical stress, whereas French does not. In the discrimination task, the French listeners’ performance was better than that of the English listeners. For each group, discrimination of the Tone 1 (T1)–T4 and Tone 2 (T2)–T3 pairs was consistently and significantly lower than that of the other tone pairs, and the difference between T1-T4 and T2-T3 was significant. Discrimination of the Mandarin tone pairs was not fully predicted by pairwise categorizations to native i-Categories, however. Some discrimination differences were observed among tone pairs showing the same assimilation patterns. Phonetic overlaps in native i-Category choices for the Mandarin tones, strength of categorization (So, 2012), and tonal coarticulation effects (Xu, 1994, 1997) may offer possible accounts of these discrepancies between categorization and discrimination performance. These findings support the perceptual assimilation model for suprasegmentals (So & Best, 2008, 2010a, 2010b, 2011, 2013), extended to categorization of nonnative tone words within sentence contexts to native i-Categories.

Assimilation of L2 vowels to L1 phonemes governs L2 learning in adulthood: a behavioral and ERP study.

According to the Perceptual Assimilation Model (PAM), articulatory similarity/dissimilarity between sounds of the second language (L2) and the native language (L1) governs L2 learnability in adulthood and predicts L2 sound perception by naïve listeners. We performed behavioral and neurophysiological experiments on two groups of university students at the first and fifth years of the English language curriculum and on a group of naïve listeners. Categorization and discrimination tests, as well as the mismatch negativity (MMN) brain response to L2 sound changes, showed that the discriminatory capabilities of the students did not significantly differ from those of the naïve subjects. In line with the PAM model, we extend the findings of previous behavioral studies showing that, at the neural level, classroom instruction in adulthood relies on assimilation of L2 vowels to L1 phoneme categories and does not trigger improvement in L2 phonetic discrimination. Implications for L2 classroom teaching practices are discussed.

Investigating the role of articulatory organs and perceptual assimilation in infants' discrimination of native and non‐native fricative place contrasts

ABSTRACTThe perceptual assimilation model (PAM; Best, C. T. [1995]. A direct realist view of cross‐language speech perception. In W. Strange (Ed.), Speech perception and linguistic experience: Issues in cross‐language research (pp. 171–204). Baltimore, MD: York Press.) accounts for developmental patterns of speech contrast discrimination by proposing that infants shift from untuned phonetic perception at 6 months to natively tuned perceptual assimilation at 11–12 months, but the model does not predict initial discrimination differences among contrasts. To address that issue, we evaluated the Articulatory Organ Hypothesis, which posits that consonants produced using different articulatory organs are initially easier to discriminate than those produced with the same articulatory organ. We tested English‐learning 6‐ and 11‐month‐olds' discrimination of voiceless fricative place contrasts from Nuu‐Chah‐Nulth (non‐native) and English (native), with one within‐organ and one between‐organ contrast from each language. Both native and non‐native contrasts were discriminated across age, suggesting that articulatory‐organ differences do not influence perception of speech contrasts by young infants. The results highlight the fact that a decline in discrimination for non‐native contrasts does not always occur over age. © 2014 Wiley Periodicals, Inc. Dev Psychobiol 56: 210–227, 2014.

Discrimination of Arabic contrasts by American learners

This article reports on second language perception of non-native contrasts. The study specifically tests the perceptual assimilation model (PAM) by examining American learners’ ability to discriminate Arabic contrasts. Twenty two native American speakers enrolled in a university level Arabic language program took part in a forced choice AXB discrimination task. Results of the study provide partial evidence for PAM. Only two-category contrasts followed straightforwardly from PAM; discrimination results of category-goodness difference and both uncategorizable contrasts yielded partial support, while results of uncategorized versus categorized contrast discrimination provided counter-evidence to PAM.

Cross-Language Perception of Cantonese Vowels Spoken by Native and Non-native Speakers

This study examined the effect of native language background on listeners' perception of native and non-native vowels spoken by native (Hong Kong Cantonese) and non-native (Mandarin and Australian English) speakers. They completed discrimination and an identification task with and without visual cues in clear and noisy conditions. Results indicated that visual cues did not facilitate perception, and performance was better in clear than in noisy conditions. More importantly, the Cantonese talker's vowels were the easiest to discriminate, and the Mandarin talker's vowels were as intelligible as the native talkers' speech. These results supported the interlanguage speech native intelligibility benefit patterns proposed by Hayes-Harb et al. (J Phonetics 36:664-679, 2008). The Mandarin and English listeners' identification patterns were similar to those of the Cantonese listeners, suggesting that they might have assimilated Cantonese vowels to their closest native vowels. In addition, listeners' perceptual patterns were consistent with the principles of Best's Perceptual Assimilation Model (Best in Speech perception and linguistic experience: issues in cross-language research. York Press, Timonium, 1995).

Perception and production in non-native speech: Russian palatalization

It is well known that adults struggle in perceiving and producing certain phonological contrasts not present in their native language. Adults also find difficulty in learning the specific timing of non-native articulatory gestures and contextual differences present in the language. The present study investigates English speakers’ perception and production of Russian contrasts involving palatalized consonants in varying contexts. Of interest are the effects of syllable position and palatalization on speakers’ performance in perception and production. The framework of Articulatory Phonology [e.g., Browman and Goldstein (1986), (1992)] and the Perceptual Assimilation Model [e.g., Best et al. (2001)] are adopted to account for differences in timing between English and Russian with respect to palatalization, and to subsequently make predictions on English speakers’ perception as well as their production of the different timing property present in Russian palatalization. Speakers of American English lacking any previous exposure to Russian participated in a series of perception and production experiments involving Russian palatalized stops, which vary in place of articulation (labials, coronals) and syllable position (onset, coda). Preliminary results indicate diminished performance for some contrasts in syllable coda position as well as correlations between the perception and production of palatalized consonants by English speakers.

First language suprasegmentally-conditioned syllable length distinctions influence perception and production of second language vowel contrasts

AbstractAdult second language (L2) learners often have difficulty perceiving and producing L2 speech segments with native-like accuracy. The Speech Learning Model (SLM; Flege 1995) attributes this to perceptual distance between native (L1) and L2 segments, the Perceptual Assimilation Model (PAM; Best 1995; Best and Tyler 2007) to L1 assimilation of L2 segmental contrasts. In a novel extension of these models, we examined whether experience with an L1 suprasegmental duration contrast can affect performance on L2 segmental vowel distinctions that are non-contrastive in the L1. Serbian employs an unusual type of relevant suprasegmental duration distinction, specifically morphological alternations in pitch-accented syllable duration. We assessed L1-Serbian participants' perception and production of L2-English /i-ɪ/ versus /æ-ɛ/, which involve both spectral and temporal distinctions but differ in magnitude of their temporal difference. The results indicate that experience with L1 syllable durations conditioned by pitch-accent systematically influences perception and production of L2 vowel contrasts.

The Discrimination of English Vowels by Cantonese ESL Learners in Hong Kong: A Test of the Perceptual Assimilation Model

This article discusses the results of a study which investigated Cantonese ESL learners’ perception of English vowels and their perceived similarity between similar L1 and L2 vowels in an attempt to test the prediction of the Perceptual Assimilation Model (PAM). Forty university English majors participated in three L2 perception tasks, which aimed at discerning their perception of English vowels spoken in different contexts, and one L1 L2 speech perception task, which aimed at discerning their classification of L2 vowels into native vowel categories and their perceived similarity between similar L1 and L2 vowels. It was found that their classifications of English vowels into Cantonese vowels and their perception of the corresponding English vowels did not provide strong support for the prediction of the model. The effects and extent of native language phonological influence are yet to be determined.

The relative perceptual easiness between perceptually assimilated vowels for university-level Korean learners of American English and measurement bias in an identification test

Korean learners of American English have difficulty differentiating between [i] and [?], [?] and [ae], and [?] and [u]. Perceptual Assimilation Model might say that the three vowel pairs are “assimilated” to Korean [i], [e] and [u], respectively. Even though these vowels are perceptually difficult, there might be some difference in Korean learners’ perceptual performance in identifying these vowels. A forced-choice identification test with spoken hVd stimuli was conducted and resulting confusion matrices were built. Then, accuracy was computed to see if there might be any perceptual performance difference between perceptually assimilated vowels on the one hand, and between perceptually assimilated vowel pairs on the other. It was found that accuracy turned out to be problematic due to accompanying bias. F-score in information retrieval was proposed as a better measure. It was found that high vowels were easier than non-high vowels and [i] and [?] are easier to perceive than [?] and [ae], respectively.

The neural basis of non-native speech perception in bilingual children.

The goal of the present study is to reveal how the neural mechanisms underlying non-native speech perception change throughout childhood. In a pre-attentive listening fMRI task, English monolingual and Spanish-English bilingual children - divided into groups of younger (6-8yrs) and older children (9-10yrs) - were asked to watch a silent movie while several English syllable combinations played through a pair of headphones. Two additional groups of monolingual and bilingual adults were included in the analyses. Our results show that the neural mechanisms supporting speech perception throughout development differ in monolinguals and bilinguals. While monolinguals recruit perceptual areas (i.e., superior temporal gyrus) in early and late childhood to process native speech, bilinguals recruit perceptual areas (i.e., superior temporal gyrus) in early childhood and higher-order executive areas in late childhood (i.e., bilateral middle frontal gyrus and bilateral inferior parietal lobule, among others) to process non-native speech. The findings support the Perceptual Assimilation Model and the Speech Learning Model and suggest that the neural system processes phonological information differently depending on the stage of L2 speech learning.