Elsevier

Acta Psychologica

Volume 128, Issue 3, July 2008, Pages 416-430
Acta Psychologica

Language selection in bilingual speech: Evidence for inhibitory processes

https://doi.org/10.1016/j.actpsy.2008.02.001Get rights and content

Abstract

Although bilinguals rarely make random errors of language when they speak, research on spoken production provides compelling evidence to suggest that both languages are active when only one language is spoken (e.g., [Poulisse, N. (1999). Slips of the tongue: Speech errors in first and second language production. Amsterdam/Philadelphia: John Benjamins]). Moreover, the parallel activation of the two languages appears to characterize the planning of speech for highly proficient bilinguals as well as second language learners. In this paper, we first review the evidence for cross-language activity during single word production and then consider the two major alternative models of how the intended language is eventually selected. According to language-specific selection models, both languages may be active but bilinguals develop the ability to selectively attend to candidates in the intended language. The alternative model, that candidates from both languages compete for selection, requires that cross-language activity be modulated to allow selection to occur. On the latter view, the selection mechanism may require that candidates in the nontarget language be inhibited. We consider the evidence for such an inhibitory mechanism in a series of recent behavioral and neuroimaging studies.

Introduction

When bilinguals perform even the simplest production task, such as speaking the name of a familiar object in one of their two languages, there is evidence that both languages are active and influence performance (e.g., Colomé, 2001, Costa et al., 1999, Hermans et al., 1998, Kroll et al., 2006). Although there is abundant evidence for parallel activity of the bilingual’s two languages in comprehension tasks (e.g., Spivey and Marian, 1999, Van Heuven et al., 1998), finding that the unintended language is available during spoken production remains surprising. Unlike the bottom–up processing that characterizes word recognition (e.g., Dijkstra & Van Heuven, 2002), speaking is initiated by a conceptually-driven process that takes a thought and maps it on to available lexical information. In theory, the conceptual nature of spoken production should allow the language to be selected early in speech planning as one aspect of the thought to be expressed. Although some instances of early language selection may be possible, for example, when bilinguals who have a stronger first (L1) than second (L2) language speak in their L1 (e.g., Bloem and La Heij, 2003, La Heij, 2005), most recent studies of bilingual word production have shown that the intention to speak one language only does not suffice to limit activation to alternatives in that language alone.

A striking aspect of bilingual speech is that proficient bilinguals do not make random errors of language. At the same time, they are able to code switch with ease with others who are similarly bilingual (e.g., Muysken, 2000, Myers–Scotton, 2002). Although one might argue that fluency at the level of sentence or discourse production is supported by a range of mechanisms that might be unavailable in decontextualized word production, the fact remains that bilingual spoken production is better than what might be expected if we assume that both languages are available in parallel and potentially compete for selection. That observation has led some to propose that bilinguals possess an exquisite mechanism of cognitive control that develops as they gain skill in the L2 (e.g., Green, 1998) and that has consequences more generally for executive control processes (e.g., Bialystok, Craik, Klein, & Viswanathan, 2004) and for their neural representation (e.g., Abutalebi & Green, 2007).

Understanding the way in which spoken word production is accomplished in bilinguals when two or more alternatives are available requires that the nature of cross-language activity be characterized and that a mechanism of selection be specified. A number of previous studies have considered the first of these questions in detail (see Costa, 2005, and Kroll et al., 2006, for recent reviews). The available evidence provides support for a number of different loci of cross-language activation during the planning of a single word utterance. Fig. 1 is a representative model of bilingual word production adapted from previous work by Hermans, 2000, Poulisse and Bongaerts, 1994. The general assumption in models of lexical production (e.g., De Bot and Schreuder, 1993, Levelt, 1989) is that at least three component processes must be engaged prior to articulation. A concept and its closest lexical representation must be selected and the phonology that corresponds to that lexical representation must be specified. For bilinguals, because there are multiple alternatives in each language, there can be activation of abstract candidates at the lemma level or among phonological competitors.1 Note that the model illustrated in Fig. 1 assumes that a language cue represents the intention to name the object in one of the two languages. As we will discuss later, the representation of the intention to speak one language alone may be influenced by the relative dominance of the two languages for the bilingual, by the context in which spoken production occurs, and by features of the two languages themselves.

Kroll et al. (2006) argued that cross-language alternatives may be active at any of the loci shown in the model. The degree to which there is sustained activity of the nontarget language will depend on a variety of factors, including the language of production, proficiency in the L2, the task that initiates speech planning, and the degree to which specific lexical alternatives are primed. As noted above, when production occurs in L1, there may be little evidence of L2 influence because L1 is more skilled than L2 and the rapid time course of speech planning in L1 may not provide an opportunity for L2 to come into play (e.g., Bloem and La Heij, 2003, Kroll et al., in preparation).

In contrast, when bilinguals speak in the L2, particularly when they are more dominant in L1, there may be multiple influences of L1 on L2 (e.g., Costa et al., 2000, Costa et al., 2006, Hermans et al., 1998, Hoshino and Kroll, 2008). Notably, these cross-language interactions in production appear to function between lexical and sub-lexical levels (Costa, La Heij, & Navarrete, 2006), to extend to feed-back as well as feed-forward interactions (Kroll et al., in preparation), and to late specification of the phonetic properties of realized speech (e.g., Engstler and Goldrick, 2007, Gerfen et al., 2005).

Although there is not complete agreement about the extent to which each result in the past studies uniquely demonstrates the presence and the locus of cross-language activation in the planning of words in each of the bilingual’s two languages (see Costa et al., 2006), taken together, the evidence is quite compelling. If alternatives are active in the two languages, how is the correct word selected? Two types of selection mechanisms have been contrasted. According to a language-specific selection model (e.g., Costa et al., 1999), information about words in the unintended language may be activated but those words are not candidates themselves for selection. Note that the presence of cross-language activation itself rules out an extreme language-specific model in which one of the two languages is effectively switched off or inhibited in advance to enable the bilingual to function as a monolingual speaker (and see Wang, Xue, Chen, Xue, & Dong, 2007, for recent neuroimaging evidence suggesting that there is no brain area uniquely associated with a language switch). The proposed language-specific model is functionally a “mental firewall” such that the language cue effectively signals the activated alternatives that are on the right side of the wall. A threshold version of the language-specific model assumes that the language cue acts to set the activation level higher for candidates in the target language, thereby avoiding potential competition between them at the point when selection occurs. Finkbeiner, Gollan, and Caramazza (2006) proposed the threshold model to be a mechanism to avoid what they consider to be the “hard” problem of lexical competition. In contrast, the non-specific language model assumes that words in both languages are potential candidates for selection. The non-specific language model allows competition for selection such that candidates within and across languages actively compete with alternatives in the unintended language which are eventually inhibited to allow accurate production to proceed (e.g., Green, 1998). Costa and Santesteban (2004) recently proposed a reconciliation of these alternatives by arguing that more proficient bilinguals have acquired the skills to avoid the “hard” problem, whereas L2 learners and less proficient bilinguals may be more likely to face cross-language competition that requires subsequent inhibition. On this view, the models are both correct but describe different states of bilingualism.

In the remainder of this paper we consider the selection models in more detail, reviewing existing findings as well as new evidence that we believe provides a more compelling case for the need for an inhibitory mechanism for even proficient bilinguals. In the course of our review, we consider the role that the production tasks used may have contributed to this debate and the evidence that bilinguals can exploit language-specific cues when they are present. Most critically, we consider the emerging literature that examines the neural basis of language selection using event related potentials (ERPs) and functional magnetic resonance imaging (fMRI) to examine the time course and localization of bilingual speech planning processes.

Section snippets

Testing accounts of language selection using behavioral evidence

Three approaches have been adopted to test the language-specific vs. non-specific models of spoken word production. The first approach is to use a variant of the Stroop task (Stroop, 1935) in which pictures are named (e.g., Hermans et al., 1998) or words are translated (e.g., LaHeij et al., 1990). During speech planning, a distractor word, related to the name of the picture or word to be translated, is presented visually or auditorily. The general prediction is that at the point in planning

ERP and fMRI studies of bilingual word production

In the search for a locus of selection effects in bilingual word processing, we and others have turned to methods that can better elucidate the time course and locus of cognitive processes involved in selecting and producing words in both the languages. The different accounts of language selection that we have already discussed would seem to make contrasting hypotheses about the time at which these effects should reveal themselves. Accounts which claim that language cues, operating at a

Conclusions: interpreting the evidence on language selection

The behavioral and neuroimaging studies we have reviewed suggest that the problem of language selection is indeed a hard problem, contrary to the suggestion that it may be possible to bypass processes that negotiate competition and potential inhibition across the bilingual’s two languages (Finkbeiner et al., 2006). The available evidence is not conclusive, as this is a relatively young area of investigation and like other research on bilingualism, there are a host of factors whose influence is

Acknowledgements

The writing of this article was supported in part by NSF Grant BCS-0418071 and NIH Grant F33HD055003 to Judith F. Kroll, by NIH Grant R56-HD053146 to Judith F. Kroll, Maya Misra, Taomei Guo, and Chip Gerfen, and by the Open Project Grant at State Key Laboratory for Cognitive Neuroscience and Learning, Beijing Normal University to Judith F. Kroll, Maya Misra, and Taomei Guo, and by the National Natural Science Foundation of China (30600179) to Taomei Guo.

References (88)

  • T.H. Gollan et al.

    More use almost always means a smaller frequency effect: Aging, bilingualism, and the weaker links hypothesis

    Journal of Memory and Language

    (2008)
  • N. Hoshino et al.

    Cognate effects in picture naming: Does cross-language activation survive a change of script?

    Cognition

    (2008)
  • I. Ivanova et al.

    Does bilingualism hamper lexical access in speech production?

    Acta Psychologica

    (2008)
  • S.A. Kotz et al.

    The role of proficiency on processing categorical and associative information in the L2 as revealed by reaction times and event-related brain potentials

    Journal of Neurolinguistics

    (2004)
  • R.F.I. Meuter et al.

    Bilingual language switching in naming: Asymmetrical costs of language selection

    Journal of Memory and Language

    (1999)
  • E.M. Moreno et al.

    Switching languages, switching palabras (words): An electrophysiological study of code switching

    Brain and Language

    (2002)
  • B.M. Schmitt et al.

    Electrophysiological estimates of semantic and syntactic information access during tacit picture naming and listening to words

    Neuroscience Research

    (2001)
  • A.I. Schwartz et al.

    Bilingual lexical activation in sentence context

    Journal of Memory and Language

    (2006)
  • W.J.B. Van Heuven et al.

    Orthographic neighborhood effects in bilingual word recognition

    Journal of Memory and Language

    (1998)
  • Y. Wang et al.

    Neural bases of asymmetric language switching in second-language learners: An ER-fMRI study

    NeuroImage

    (2007)
  • J.C. Ziegler et al.

    Neighborhood effects in auditory word recognition: Phonological competition and orthographic facilitation

    Journal of Memory and Language

    (2003)
  • Abutalebi, J., Annoni, J. M., Zimine, I., Pegna, A. J., Seghier, M. L., Lee-Jahnke, H. et al. (in press). Language...
  • A. Allport et al.

    Shifting intentional set: Exploring the dynamic control of tasks

  • M.C. Anderson et al.

    Remembering can cause forgetting: Retrieval dynamics in long-term memory

    Journal of Experimental Psychology: Learning, Memory and Cognition

    (1994)
  • E. Bialystok et al.

    Bilingualism, aging, and cognitive control: Evidence from the Simon task

    Psychology and Aging

    (2004)
  • A. Costa

    Lexical access in bilingual production

  • A. Costa et al.

    The cognate facilitation effect: Implications for the model of lexical access

    Journal of Experimental Psychology: Learning, Memory, and Cognition

    (2000)
  • A. Costa et al.

    The dynamics of bilingual lexical access

    Bilingualism: Language and Cognition

    (2006)
  • A. Costa et al.

    The lexical bias effect in bilingual speech production: Evidence for feedback between lexical and sublexical levels across languages

    Psychonomic Bulletin & Review

    (2006)
  • A. Costa et al.

    How do highly proficient bilinguals control their lexicalization process? Inhibitory and language-specific selection mechanisms are both functional

    Journal of Experimental Psychology: Learning, Memory, and Cognition

    (2006)
  • K. De Bot et al.

    Word production and the bilingual lexicon

  • E.R.A. De Bruijn et al.

    Language context effects on interlingual homograph recognition: Evidence from event-related potentials and response times in semantic priming

    Bilingualism: Language and Cognition

    (2001)
  • A.M.B. De Groot

    Determinants of word translation

    Journal of Experimental Psychology: Learning, Memory, and Cognition

    (1992)
  • T. Dijkstra

    Bilingual word recognition and lexical access

  • A. Dijkstra et al.

    The architecture of the bilingual word recognition system: From identification to decision

    Bilingualism: Language and Cognition

    (2002)
  • W. Duyck et al.

    Visual word recognitions by bilinguals in a sentence context: Evidence for nonselective access

    Journal of Experimental Psychology: Learning, Memory, and Cognition

    (2007)
  • K. Emmorey et al.

    Bimodal bilingualism: Code-blending between spoken English and American sign language

  • Engstler, C., & Goldrick, M. (2007). Lexically conditioned variation across languages. In Poster presented at the 4th...
  • M. Finkbeiner et al.

    Lexical selection in bilingual speech production does not involve language suppression

    Journal of Experimental Psychology: Learning, Memory, and Cognition

    (2006)
  • M. Finkbeiner et al.

    Bilingual lexical access: What’s the (hard) problem?

    Bilingualism: Language and Cognition

    (2006)
  • W.S. Francis

    Bilingual semantic and conceptual representation

  • W.S. Francis et al.

    Repetition priming in picture naming and translation depends on shared processes and their difficulty

    Journal of Experimental Psychology: Learning, Memory, and Cognition

    (2003)
  • Gerfen, C., Jacobs, A., & Kroll, J. F. (2005). Inhibiting first language phonology in planning and producing speech in...
  • T.H. Gollan et al.

    What is a TOT? Cognate and translation effects on tip-of-the-tongue states in Spanish–English and Tagalog–English bilinguals

    Journal of Experimental Psychology: Learning, Memory, and Cognition

    (2004)
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